THE YUGOSLAV CAMPAIGN
Political and Strategic Planning
Upon his assumption of power on 27 March 1941, General Simovic, the new head of the Yugoslav Government, was faced with a difficult situation. Realizing that Germany was making feverish preparations to invade Yugoslavia, he tried his utmost to unify his government by including representative Croat elements. It was not until 3 April— just three days before the German attack was launched--that the Croat leaders finally joined the Simovic government. Upon entering the cabinet, Croat representatives appealed to their people to give the new regime wholehearted support. However, any semblance of national solidarity was to be short lived. When Croatia proclaimed itself an independent state with Hitler's blessings on 10 April, the Croat political leaders promptly left the national government in Belgrade and returned to Zagreb. Thus the cleft in Yugoslavia's national unity, superficially closed for exactly seven days, became complete.
While the Simovic government made every effort to maintain friendly relations with Germany, Hitler was bent on settling the issue by force of arms. Preparations for the rapid conquest of Yugoslavia were hastened so as not to jeopardize the impending campaign against Russia. Germany's limited resources precluded the possibility of tying down forces in Yugoslavia for any protracted period while simultaneously invading the Soviet Union.
The possibility of an invasion of Yugoslavia had hitherto not been considered by the German Army planners. For a better understanding of the problems with which the German General Staff officers were faced, it is necessary to examine the topographic features of that country.
1. Military Topography
Geographlically, the Balkans extend from the Danube to the Aegean and from the Black Sea to the Adriatic. (Map 1) Mountain ranges and narrow, mountain-filled valleys are characteristic of the Balkan peninsula, of which Yugoslavia constitutes the northwestern and central portion. Central Yugoslavia is a plateau that slopes gently toward the Danube Valley and gradually merges into the Hungarian plains.
The Yugoslav coastline along the Adriatic extends for approximately 400 miles and is fronted by numerous small islands. The Dalmatian Alps, which run along the coast, constitute a formidable barrier as good roads are scarce. Stretching across the peninsula, roughly from east to west, are the Balkan Mountains. The ranges are high, rough, and rugged, and are intersticed by numerous passes which, however, can be successfully negotiated by specially trained and equipped mountain troops.
The inland frontiers of Yugoslavia extend some 1,900 miles and border on Italy, Austria, Hungary, Romania, Bulgaria, Greece, and Albania. Covering a land surface approximately the size of the State of Oregon, Yugoslavia has a population of almost 14; million, of which 5 million Serbs and 3 million Croats constitute the two largest ethnic groups. In the northern part of the country a German minority element numbers about half a million. The largest cities are Belgrade, the national capital, with 400,000 inhabitants and Zagreb, the principal Croat city, with 200,000
The country can be roughly divided into five distinct natural geographic regions. The so-called Pannonina Basin, within which the national capital of Belgrade is centrally located, is by far the most important industrial portion. The Sava and Drava valleys link this area with the Slovene Alps, the forerunners of the more formidable Julian Alps. The Morava-Vardar depression extends southward from Belgrade to the Greek frontier. The Adriatic coastal belt extends from Italy in the north to Albania in the south. The Dalmatian Alps rise directly out of the sea and overshadow the central mountain or Dinaric Karst region farther inland.
There are several great routes of communication in the Balkans. One of these follows the Morava and Vardar Rivers from Budapest to Salonika and connects the Danube with the Aegean. The best roads and railroad lines are to be found in the northern and northeastern fringes of Yugoslavia which formed part of the Austro-Hungarian Empire.
Because of its difficult terrain, Yugoslavia is far from being ideally suited for the conduct of major military operations. This poorly developed, rugged, and mountainous country, with its limited routes of communication and sparsely populated area, is bound to raise havoc with an invader's communications, movements, and logistical support.
Almost all of the rivers, including the Drava, Sava, and Morava, are tributaries of the Danube, which flows through the northwestern part of Yugoslavia for about 350 miles. Soon after crossing the northern border an attacking ground force is confronted by three formidable river barriers: the Mura, the Drava, and the Sava. At the time of the spring thaws these rivers resemble swollen torrents; the Drava at Bares and the lower course of the Sava become as wide as the Mississippi at St. Louis. It is therefore of vital importance for the invader to seize the key bridges across these rivers while they are still intact.
II. Hitler's Concept of the Strategic Factors
During the conference that took place on the afternoon of 27 March 1941, Hitler formulated overall strategic plans for the projected military operation against Yugoslavia. The decisions reached at this meeting were summarized in Directive No. 25, which was disseminated to the three armed services on the same day. The campaign against Yugoslavia took its cover name--Operation 25--from this directive.
Hitler declared that the uprising in Yugoslavia had drastically changed the entire political situation in the Balkans. He maintained that Yugoslavia must now be regarded as an enemy and must be destroyed as quickly as possible despite any assurances that might be forthcoming from the new Yugoslav Government. Hungary and Bulgaria were to be induced to participate in the operations by extending to them the opportunity of regaining Banat and Macedonia, respectively. By the same token, political promises were to be extended to the Croats, promises that were bound to have all the more telling effect since they would render even more acute the internal dissension within Yugoslavia.
In view of Yugoslavia's difficult terrain, the German plans called for a two-pronged drive in the general direction of Belgrade, with one assault force coming from southeastern Austria and the other from western Bulgaria. These forces were to crush the Yugoslav armed forces in the north. Simultaneously, the southernmost part of Yugoslavia was to be used as a jumpoff area for a combined German/Italian offensive against Greece. Vital as the early capture of Belgrade proper was considered to be, possession of the Belgrade-Nis-Salonika rail line and highway and of the Danube waterway was of
[Figure 2. Bridge Across the Drava River damaged by the Yugoslavs]
even greater strategic importance to the German supply system. Hitler therefore arrived at the following conclusions:
- As soon as sufficient forces became available and the weather conditions permitted, the Luftwaffe was to destroy the city of Belgrade as well as the ground installations of the Yugoslav Air Force by means of uninterrupted day-and-night bombing attacks. The launching of Operation MARITA was to coincide with the initial air bombardment.
- All forces already available in Bulgaria and Romania could be utilized for the ground attacks, one to be launched toward Belgrade from the Sofiya region, the other toward Skoplje from the Kyustendil-Gorna Dzhumaya area. However, approximately one division and sufficient antiaircraft elements must remain in place to protect the vital Romanian oil fields. The guarding of the Turkish frontier was to be left to the Bulgarians for the time being, but, if practicable, one armored division was to be kept in readiness behind the Bulgarian frontier security forces.
- The attack from Austria toward the southeast was to be launched as soon as the necessary forces could be assembled in the Graz area. The ultimate decision as to whether Hungarian soil should be used for staging the drive against Yugoslavia was to be left to the Army. Security forces along the northern Yugoslav frontier were to be reinforced at once. Even before the main attacks could be launched, crucial points should be seized and made secure along the northern and eastern Yugoslav border. Any such limited-objective attacks were to be so timed as to coincide with the air bombardment of Belgrade.
- The Luftwaffe was to lend tactical support and cover during the ground operations in the vicinity of the Yugoslav border and coordinate its efforts with the requirements of the Army. Adequate antiaircraft protection was to be provided in the vital concentration areas around Graz Klagenfurt, Villach, Leoben, and Vienna.
The Plan of Attack
I. The Outline Plan
Working under tremendous pressure, the Army High Command developed the combined outline plan for the Yugoslav and Greek campaigns within twenty-four hours of the military revolt in Yugoslavia.
After this plan had been submitted to and approved by Hitler, it was incorporated into Directive No. 25.
This outline plan envisaged the following offensive operations:
- One attack force was to drive southward from the former Austrian province of Styriaand from southwestern Hungary. This force was to destroy the enemy armies in Croatia and drive southeastward between the Sava and Drava Rivers toward Belgrade. The mobile divisions of this assault group were to coordinate their advance with the other attack forces that were to close in on the Yugoslav capital from other directions so that the bulk of the enemy forces would be unable to make an orderly withdrawal into the mountains.
- The second force was to advance toward Belgrade from the Sofiya area in western Bulgaria, take the capital, and secure the Danube so that river traffic could be reopened at an early date.
- A third attack force was to thrust from southwestern Bulgaria in the general direction of Skoplje in an effort to cut off the Yugoslav Army from the Greek and British forces, while at the same time easing the precarious situation of the Italians in Albania.
- Finally, elements of the German Twelfth Army, which were poised and reedy to invade Greece from Bulgarian bases and had the difficult task of surmounting the hazardous terrain fortified by the Metaxas Line, were to pass through the southern tip of Yugoslavia, execute an enveloping thrust via the Vardar Valley toward Salonika, and thus ease the task of the German forces that were conducting the frontal assault against the Greek fortified positions.
II. The Timing of the Attacks
In its original version, the outline plan for Operation 25 called for the air bombardment of Belgrade and the ground installations of the Yugoslav Air Force to take place on 1 April, the invasion of Greece— Operation MARITA--on 2 or 3 April, and ground attacks against Yugoslavia between 8 and 15 April.
During the afternoon of 29 March the Deputy Chief of Staff for Operations, Generalleutnant (Major General) Friedrich Paulus--who was to lead the survivors of the Stalingrad pocket into Russian captivity less than two years later--presided over a special conference in Vienna at which the plans of attack and timetable for the operations against Greece and Yugoslavia were discussed. Present with their respective chiefs of staff were Field Marshal List, the commander of Twelfth Army, Generaloberst (General) Maximilian von Weichs of Second Army, and Generaloberst (General) Ewald von Kleist of the First Panzer Group. Field Marshal List was brought up to date
on the changes in the situation necessitated by the Yugoslav campaign, and all commanders were fully briefed on the projected plans for the conduct of the operations. Decisions were reached as to which units were to participate in the various thrusts from Austria and Hungary under the command of Second Army. In addition, the corps headquarters and GHQ units were selected and assigned.
One of the subjects discussed during this meeting was the participation of Germany's allies and satellites in the Yugoslav campaign. Since the Italians in Albania had demonstrated their inability to mount any offensive operations and the Italian Second Army deployed in northern Italy apparently would not be ready for action until 22 April, any real assistance from that side was not to be expected. At any rate, according to the German Army Command plans, the Yugoslav operations would be almost completed by the time the Italians could be ready. The Hungarians acceded to all German requests for the use of their territory and agreed to take an active part in the operations by committing contingents, which were to be subordinated to the German Army High Command. At the conclusion of the conference, General Paulus proceeded to Budapest to discuss details of the operation with the Hungarian general staff.
Another result of the conference of 29 March was the decision to delay the initial air attacks so that they would coincide more closely with the attack on Greece. The purpose of this measure was to bring Operation MARITA into a closer relationship with Operation 25. The revised timetable thus foresaw that the attacks of Twelfth Army to the south and west and the air bombardment would be launched simultaneously on 6 April, the thrust of First Panzer Group on 8 April, and the Second Army attack on 12 April. These deadlines were adhered to with the exception of D-day for Second Army, which was moved up when the rapid successes scored by the probing attacks led to the decision of getting off to a "Hying start."
III. Second Army
In the final version of the plan of attack the Second Army was to jumpoff on 10 April with its mobile forces driving in the general direction of Belgrade between the Drava and Sava Rivers. The terrain between the two rivers was considered ideal for armored warfare, and no serious obstacles were expected. The army was greatly concerned, however, over the prospect of finding key bridges demolished, especially since little bridging equipment was available and the rivers were swollen by spring thaws. For this reason the lead elements of the XLVI Panzer Corps were to conduct limited objective attacks as early as 6 April in order to seize and secure the
highway and railroad bridges across the Drava near Bares. In this manner the corps would be able to launch its thrust toward Belgrade by 8 April, the same time that the First Panzer Group was to attack from the southeast. One motorized column was to be diverted to the southwest with the mission of capturing Zagreb at the earliest possible moment.
Farther to the west, where the terrain becomes more and more mountainous, the LI Infantry Corps was to jumpoff on 10 April and drive in the direction of Zagreb with two infantry divisions. Here, too, limited objective attacks were to be carried out during the preceding days so that strategic points in the proximity of the frontier could be secured.
On the same day, and as soon as sufficient troops became available, the XLIX Mountain Corps was to advance toward Celje.
IV. First Panzer Group
In compliance with Directive No. 25, Field Marshal List's Twelfth Army, which had originally been assembled in Bulgaria for the purpose of executing Operation MARITA, had to regroup its divisions into three separate attack forces. The plan of attack of the southern and central forces will be dealt with in Part III, "The (Herman Campaign in Greece." The northern attack force of Twelfth Army, led by General von Kleist's First Panzer Group, was to launch a surprise attack in the direction of Nis-Kragujevac-Belgrade on 8 April, annihilate strong enemy forces concentrated in the Pirot-Leskovac sector, and capture the Yugoslav capital with a minimum of delay.
The First Panzer Group forces had to be reorganized and regrouped for their new mission. By using every available motor vehicle, the regrouping could be achieved within a few days. For this purpose, motor vehicles from German forces stationed in Romania and from the 16th Panzer Division, deployed behind the Bulgarian-Turkish border, had to be organized into makeshift motor transport columns and hurriedly pressed into service. The forces at the disposal of the panzer group were comparatively weak, considering the difficulties they were bound to encounter. In all probability, the Yugoslavs would concentrate their best troops in the vicinity of the capita], which was not easily accessible from the southeast. The German armor would be forced to negotiate some formidable mountain roads before reaching its objective. Thus, in the event that the Serbs established a well-organized defense system, this attack might involve considerable risk.
V. XLI Panzer Corps
To coincide with this thrust, the XLI Panzer Corps, which was assembling in western Romania, was to undertake a separate drive from the Timisoara area to Belgrade. The outline plan did not envision the employment of the XLI Panzer Corps during the Yugoslav campaign. However, without consulting the Army High Command, Hitler ordered the Id SS Motorized Infantry Division to advance on Belgrade from Timisoara. He apparently wanted an SS division to be the first to enter the Yugoslav capital, both for prestige reasons and propaganda purposes. Upon learning of this move, the Army High Command protested vigorously and soon obtained complete operational control over this force, which subsequently formed the third prong in the drive on Belgrade.
The Defense Forces
Lacking up-to-date materiel, the Yugoslav armed forces were no match for the well-equipped and highly trained German war machine. Their deficiencies were particularly marked in the fields of aviation and armor. In January 1911 the Yugoslav Air Force numbered approximately 700 military aircraft, most of which were obsolete. A major portion of all weapons and equipment was of foreign make, with the Skoda armament plant the main source. After the Germans annexed the whole of Czechoslovakia in 1939, deliveries from that source ceased almost completely. In the opinion of some German military experts the pronounced inferiority of Yugoslav equipment and material was partly compensated for by the inaccessibility of the country and toughness of the individual soldier. However, internal friction among the different ethnic groups, particularly between Serbs and Croats, undermined the overall combat effectiveness of the Yugoslav military forces.
II. Defensive Plans
The Yugoslav plan of defense called for a fairly even distribution of all available forces along the extended frontiers of the country. In adopting a cordon defense the Yugoslav high command displayed little ingenuity as it deprived itself of the opportunity of forming strong reserves. Since the capital of Belgrade and the industrial area around Nis and Kragujevac were situated so close to the frontier, major elements of the Army were tied down in the defense of those
[Figure 3. Yugoslav obstacles across the railway tracks near Spielfeld]
sectors. Moreover, the Yugoslav command intended to maintain contact with the Greek and British troops in Greece by strengthening its forces in northern Macedonia. In conjunction with a Greek attack from the south, the Yugoslav high command planned to commit the Third Army in a drive against Albania from the east. While this attack force was to push the Italians out of Albania, the other armies were to fight delaying actions if any frontier sector should be invaded by Germany. In the event of initial setbacks in the border areas, the Yugoslavs intended to conduct an orderly withdrawal into the inaccessible mountainous regions in the western part of the country, where they hoped to continue their resistance by engaging the invader in costly and time consuming guerrilla warfare.
This plan was unrealistic and therefore bound to fail. The Yugoslav Army could have escaped total annihilation only if it had operated in conjunction with the Greek and British forces and had built up a line of resistance in the extreme southern part of the country to achieve this purpose. This line should have been anchored on the Greek front in Albania in the west and on the mountains along the Greek-Bulgarian frontier in the east. This would have meant the voluntary abandonment of almost the entire national territory, a decision which no Yugoslav political leader could possibly have envisaged.
III. Training and Tactics
Combined-arms training and maneuvers under simulated combat conditions had been seriously neglected by the Yugoslavs. During training much emphasis was placed on delaying actions, defensive fighting, and the conduct of counterattacks. Considerable weight was also attached to assault tactics of infantry forces. The individual Serb soldier was well trained in close-combat and hand-to-hand fighting, but was powerless against heavy artillery fire and air-supported armored thrusts.
IV. Guerrilla Warfare
Special emphasis was placed on guerrilla warfare, for which the Serbs were especially well suited and trained. The "Cetnici," a partisan organization composed of loyal Serbs, had been formed into militia units of varying size up to battalion strength. Its primary mission was to carry out raids and acts of sabotage against enemy command posts and rear area installations. Guerrilla units were to be committed to reinforce the frontier guards so that they could wage their specialized type of warfare against an attacker from the very outset of operations.
There was no continuous line of fortifications along the Yugoslav frontier. Although pillboxes had been constructed in certain places to reinforce individual strong points, these were at best interconnected by unimproved, open trenches. None of the pillboxes had armor plated cupolas; they were armed primarily with machine guns and, in some instances, with antitank and light artillery guns. Though these fortified positions were far from imposing, they were, as a rule, well concealed and camouflaged. Several rows of wire entanglements protected the positions. At some points tank obstacles and antitank ditches were built in front of the fortified lines. The obstacles consisted of from three to five rows of steel girders which had merely been driven into the ground but were not anchored in a concrete foundation. Consequently, they did not constitute a formidable barrier for the modern-type medium tank. The antitank ditches, though few in number, were well conceived and effectively constructed. They measured twenty-four feet in width and nine feet in depth, and their steep retaining wall was revested.
Because of the mountainous terrain along the German-Yugoslav frontier, the defense system in this area was limited to blocking main roads and key mountain passes where a German penetration was most likely to occur. It was here that most of the fortified positions had been constructed. Their size and strength varied depending on the importance of the border-crossing point and on the natural terrain features.
VI. Order of Battle
At the beginning of April 1941 the Yugoslav Army was composed of seventeen regular and twelve reserve infantry divisions, six combined-arms brigades, three regular cavalry divisions and three reserve cavalry brigades, one fortress division, and one fortress brigade. There were also twenty-three frontier guard battalions, a number of frontier guard regiments, and some fortification troops. The fully mobilized strength of the Army was slightly under 1,000,000 men.
The divisions and brigades were not designated numerically, as is normally the case, but were named after provinces, rivers, mountain ranges, or cities. They were organized into three army groups seven field armies, and one coastal defense command. The following were their composition and primary missions on 6 April 1941:
- The First Army Group consisted of: the Seventh Army, including two infantry divisions, two mountain brigades, and onecoastal defense battalion, was responsible for the defense of the northwestern of the country facing the Italian and German frontiers; the Fourth Army, composed of three infantry divisions and one cavalry brigade, was to hold the sector facing the Hungarian border, and was deployed behind the Drava from Varazdin to Slatina. Behind this defense line a cavalry division stood in reserve in the Zagreb area, while three additional infantry divisions were held in reserve south of the Croat capital.
- The Second Army Group was composed of: the Second Army including three infantry divisions holding the sector adjacent to Fourth Army up to the Danube; one additional infantry division which was located south of Brod and formed the army reserve; and the First Army, which consisted of one cavalry and two infantry divisions, and occupied the northwest corner between the Danube and the Tisza.
- The Sixth Army was an independent command not subordinated to an army group. It was composed of two infantry divisions, one infantry brigade, one reinforced cavalry division, and one reinforced cavalry brigade. These forces were deployed around Belgrade and in the Banat region east of the Tisza. Two additional infantry divisions were upheld in reserve along both banks of the lower Morava Valley.
- The Third Army Group consisted of: the Fifth Army, which had four infantry divisions and two infantry brigades to cover the Romanian border from the Iron Gate up to Kriva Palanka; three additional infantry divisions under the army's jurisdiction covered the adjacent sector to the south, extending to the Greek frontier; and the Third Army, composed of four infantry divisions and one separate battalion, which was deployed along the Albanian border from Lake Ohridsko to Lake Shadarsko. One infantry division was held in reserve in the Skoplje area.
- The Coastal Defense Command had at its disposal one infantry division as well as the Kotorski Fortress Division and the Sibenik Fortress Brigade. This command was responsible for the defense of the Adriatic coast from the Bay of Kotorski to Gospic.
VII. Deficiencies and Confusion
Because of the political situation, the inadequate rail and road nets, and the poor organization of the Army as a whole, the Yugoslav defense forces were committed piecemeal. The frontier defenses, although built around favorable terrain features, lacked depth and usually confined themselves to the immediate border environs.
When hostilities began on 6 April, the Yugoslav Army was still in the midst of mobilization, with sizable forces being clothed and equipped in their garrisons. As a result, the disposition of troops behind the 1,900-mile border was totally inadequate. The only units that were fully mobilized were the regular Army divisions of the Third and Fifth Armies, which were stationed along the Bulgarian border. Some of the border security battalions were on a war footing, but even they were understrength. Not until 3 April did the Yugoslavs start to shift troop units from the interior to the Bulgarian frontier. No strategic reserves whatsoever were available in the Ljubljana area in the north.
During his discussions with Yugoslav leaders in Belgrade on 1 April, General Sir John Dill, Chief of the British Imperial General Staff, found nothing but confusion and paralysis. Political leaders repeatedly stated that Yugoslavia was determined not to take any steps that might provoke a German armed attack. Obviously, the Yugoslav ministers failed to realize the imminence of their country's peril. Their mood and outlook left Dill under the impression that they believed they would have months to make their decisions and enforce their plans, whereas in reality only a few days were to elapse before the Germans launched their attack.
The Attack Forces
I. Command Posts
On 5 April Field Marshall Walther von Brauchitsch, Commander in Chief of the Germany Army, moved to Wiener Neustadt (thirty-five miles south of Vienna) in order to assume personal command of the Second and Twelfth Armies, which were to conduct the campaigns against Yugoslavia and Greece. He was accompanied by an advance echelon of the Army General Staff. Reichs Marshal Goering, Commander in Chief of the Luftwaffe, established his field headquarters at Semmering Pass, southwest of Wiener Neustadt.
Accompanied by his close entourage and the forward echelon of the National Defense Branch of the Armed Forces Operations Staff, Hitler departed from Berlin on the evening of 10 April. On the following day the Fuehrer arrived at a small station on the single-track railroad line leading from Wiener Neustadt southward to Fuerstenberg (fifty miles east of Graz). There, his special train and that of the National Defense Branch halted in front of the northern and southern exits respectively of a tunnel that leads through the Alps south of Aspang.
From these locations the trains could easily be pulled into the tunnel in the event of enemy air attacks. While the two trains remained in the area, the entire line was blocked to normal traffic. It was from this vantage point that Hitler directed the Balkan campaigns until 25 April, when he returned to Berlin.
II. The Luftwaffe
The ground operations in the Balkans were to be given strong and effective air support by the Fourth Air Force under the command of General der Flieger (Lieutenant General) Alexander Loehr, whose headquarters was then located in Vienna. The actual air operations were carried out by the VIII Air Corps of General der Flieger (Lieutenant General) Wolfram von Richthofen. It was he who had established such an outstanding record in supporting the slashing armored thrusts during the Battle of France.
Between November 1940 and February 1941, a force of over 400 planes, including long-range bombers, dive-bombers, fighters, and reconnaissance aircraft, had gradually been built up in Romania and Bulgaria. By 27 March, when the Yugoslav revolt occurred, there were 135 fighter and reconnaissance planes in Romania, and 355 bombers and dive-bombers in Bulgaria.
Early in April additional air reinforcements were rushed to the Balkans. From as far away as France, Africa, and Sicily about 600 aircraft of all four types were brought up and readied for action within ten days. The fighter and reconnaissance craft were sent to fields near Arad, Deva, and Turnu-Severin in western Romania, all within easy striking distance of Belgrade. The long-range bombers were to operate from fields at Wiener Neustadt and near Sofiya, northwest and southeast of the Yugoslav capital, at 200 and 100 miles distance, respectively.
III. Second Army
The disposition and order of battle of the various attack groups under Second Army were as follows (appendix I):
[Figure 4. German supply collumns crossing a 4,100-foot pass in Bulgaria
- The XLIX Mountain Corps under General der Infanterie (Lieutenant General) Ludwig Kuebler was assembled in the Klagenfurt area. The only two divisions originally assigned to this corps were the 1st Mountain and the 538th Frontier Guard Divisions.
- The LI Infantry Corps of General der Infanterie (Lieutenant General) Hans Reinhardt moved into the Leibnitz area. This corps composed of the 101st Light Infantry and 132d and 183d Infantry Divisions, was to form the main effort of the southward thrust.
- The LII Infantry Corps, under the command of General der Infanterie (Lieutenant General) Kurt von Briesen, consisted of two infantry divisions, the 79th and 125th, which were supposed to be committed alongside LI Corps. Since these forces did not arrive in time and were eventually not needed for the operation, they were placed in the Army High Command reserve.
- XLVI Panzer Corps, under the command of General der Panzertruppen (Lieutenant General) Heinrich von Vietinghoff, was assembled in southwestern Hungary near Nagykanizsa. It was composed of the 8th and 14th Panzer Divisions and the 16th Motorized Infantry Division.
IV. First Panzer Group
The First Panzer Group headquarters under General von Kleist had originally been designated to command the spearhead divisions in the campaign against Greece. After the revision of plans the following units were assigned to the panzer group and diverted to participate in the Yugoslav campaign:
- The XIV Panzer Corps, under the command of General der Infanterie (Lieutenant General) Gustav von Wietersheim, composed of the 5th and 11th Panzer, the 294th Infantry, and the 4th Mountain Divisions.
- The XI Infantry Corps, under the command of General der Infanterie (Lieutenant General) Joachim von Kortzfleisch, consisted of the 60th Motorized Infantry Division and several other units which, however, did not participate in the campaign.
V. XLI Panzer Corps
An independent armored corps, the XLI Panzer Corps, was assembled in western Romania near Timisoara under the command of General der Panzertruppen (Lieutenant General) Georg-Hans Reinhardt. It comprised the 2d SS Motorized Infantry Division, the reinforced Motorized Infantry Regiment "Gross Deutschland," and the Panzer Regiment "Hermann Goering."
Logistical Planning and Assembly of Second Army
I. The Rail Transportation Problem
The forces assigned to Second Army had to be shifted from France and Germany as well as from the Russian border. (Map 3) In accordance with the schedule for the concentration of forces for Operation BARBAROSSA, large-scale movements to Germany's eastern border were under way toward the end of March. Consequently, the Second Army forces that were designated to participate in the Yugoslav campaign had to be rerouted toward the south, some of them even in the midst of their west-east movement. Several efficient railroad lines running from north to south were available for the movement. Two of these lines led to Vienna, one via Breslau and the other via Munich, Salzburg, and Linz. Two additional lines terminated in Passau, one via Nuremberg and the other via Munich. The line from Prague via Pilsen to Vienna was also available but had only a limited capacity.
The movements from Vienna and Passau through the Alps into the detraining areas around Graz and into western Hungary presented more complicated problems. Since the capacities of the feeder lines and detraining points were considered inadequate, some elements were forced to detrain in Vienna and Salzburg and continue the movement to the assembly areas by road.
The Graz area and western Styria were particularly difficult to reach. Here, the feeder lines traversed the Alps and were consequently of very limited capacity. For this reason it became imperative to include the western tip of Hungary as assembly area for some of the German attack forces. After Hungary had agreed to the use of its territory, the assembly of the German Second Army proceeded as follows:
1. Graz and western Styria were designated as assembly areas for all infantry divisions. Three railroad lines with the following daily feeder capacity were available in those areas:
a. The daily capacity of the line Vienna-Bruck-Graz was sixty trains from Vienna to Bruck and forty-eight from Bruck to Graz. However, only fifty-two military trains could be dispatched from Vienna to Bruck since eight trains destined for Italy were needed daily to haul coal over that stretch. These trains had to be kept running on schedule so that the German concentrations could be concealed from the Yugoslavs as long as possible.
The Campaigns in the Balkans--Deployment and Initial Objectives (542K)
b. The line Passau-Ried-Leoben had a carrying capacity of eighteen trains.
c. The line Salzburg-Spittal-Klagenfurt could also carry eighteen trains daily, but only with half the normal load because of the steep gradients across the Alps.
The daily detraining capacity of the Bruck-Graz-Klagenfurt area was seventy-eight trains, or the equivalent of the combat elements of two infantry divisions. Consequently, all of the rear echelon elements of these divisions had to detrain in the Vienna area, capable of handling 144 trains a day, and in Salzburg, where forty-eight additional trains could be unloaded. The divisional service units then had to reach the assembly areas by marching overland. However, since road conditions were poor at this time of the year, snow-clearing detachments had to be provided to keep the Salzburg-Liezen-Bruck and Vienna-Bruck-Graz roads clear. The same roads also had to be used by those divisions that moved solely by motor transportation. Since rigid traffic control was enforced and traffic regulations were strictly adhered to, the execution of these movements did not entail any undue delay.
2. The area around Nagykanizsa was selected for the assembly of the one motorized infantry and two panzer divisions subordinated to XLVI Panzer Corps headquarters. Some of the tracked vehicles moved upon the Vienna-Sopron-Nagykanizsa railroad line, whose feeder capacity was twelve trains a day. Other elements detrained in the Budapest-Szekesfehervar area and continued on to Nagykanizsa by road. Some of the motorized columns moved directly from Vienna by road since the Hungarian highways were clear of snow.
The above-mentioned capacity figures of railroads and highways were eventually reached, but not before many difficulties had been overcome. The main problem was that no preparatory work had been started until the evening of 27 March. The system of classifying all major railroad lines according to their capacity, introduced at the beginning of the war, and the method applied in processing military rail movements both proved efficient during this emergency. The maximum performance schedule, which required the almost complete stoppage of all nonmilitary traffic, had to be resorted to only on the Austrian railroads. Aside from conserving personnel and materiel, the adherence to normal train schedules whenever possible permitted the Germans to camouflage the movements to the assembly areas right up to the time when the first contingents arrived at the detraining points.
Transportation bottlenecks in the Graz area made it necessary to resort to a complicated system of segregating troop shipments. Only vital combat elements could be included in the forward echelon of the infantry divisions. All divisional units that could be temporarily dispensed with, especially the bulk of the supply trains, were either held back for later shipment or sent to detraining points located far to the rear. This was the first time that such a divorcement of combat and service echelons became necessary and was put into effect. During its subsequent application in Russia, this improvised measure was further perfected and proved to be invaluable.
The cooperative attitude of the Hungarian transportation personnel made it possible to increase the capacity of the Nagykanizsa detraining area in record time. The German Movement Control headquarters in Budapest, recently transferred from Bratislava, was responsible for the preparations that had to be completed within three days. All loading ramps in the area had to be enlarged and reinforced to handle heavy loads, new sidings had to be laid, and adequate antiaircraft protection had to be provided. To increase the capacity of the railroads in Hungary and Bulgaria, the Army railroad transportation agencies formed a reserve pool of locomotives and box cars suitable for troop transports.
Special measures also had to be taken to ensure the flow of supplies into the Balkans once the campaign had started. The line Belgrade-Nis-Salonika, the only one capable of handling fully loaded trains, was vitally needed for this purpose. Railroad engineer troops and construction equipment had to be reserved for the immediate restoration of this line after it had fallen into German hands.
The Bulgarian railroads were connected with the Belgrade-Nis-Salonika line. To avoid time consuming reloading operations, troop and supply trains destined for Bulgaria were loaded at "Balkan Capacity," which was two-thirds of the normal weight. This necessitated a rearrangement of the loading and unloading schedules, which was accomplished with the cooperation of the Bulgarian General Staff and railroad authorities.
II. The Danube as a Route of Transportation
The Danube was of vital importance to the German war effort. Oil from Romania and agricultural products from the Balkans were shipped to Germany along the great waterway. To switch this traffic to the inadequate rail net was impossible, and any disruption in the river shipping was bound to have a telling effect. With the outbreak of hostilities in Yugoslavia, all Danube shipping would have to be suspended; its resumption would depend on the progress of the
[Figure 5. German emergency bridge replaces demolished structure]
military operations as well as on the extent of demolitions and mine obstacles.
At the defile of the Iron Gate, where the Danube forms the boundary between Yugoslavia and Romania, a fairly long stretch of the river is canalized. Because of the numerous locks and dams this portion of the river was considered to be extremely vulnerable. It was known that the Yugoslavs had prepared some acts of sabotage along the Danube and intended to mine the Iron Gate. Therefore, a reinforced German engineer battalion, forming part of the military mission stationed in Romania, was assigned the task of seizing and protecting this vital area.
According to a digest of captured Yugoslav documents that was written by the Foreign and Counterintelligence Office of the Armed Forces High Command after the conclusion of the campaign, there existed a plan for blocking the Iron Gate in order to paralyze German Danube shipping. This plan, said to have been prepared by British agents in April 1940, failed because of German watchfulness. The British allegedly planned to sink cement barges in the Danube shipping channel. Moreover, they were supposed to have organized a network of local agents who were to destroy port facilities and military installations and sabotage German ships while they were in Yugoslav ports.
During the Balkan campaigns the Danube actually did not play a major role as a military route of transportation. The available shipping facilities were barely sufficient for the transportation of essential materials. Although the military transportation agencies had repeatedly pointed to the urgency of a large-scale construction program of Danube vessels, Hitler had refused to allocate the necessary steel for this purpose.
III. Other Logistical Planning
In 1941 the two best railroad lines in the Balkans ran from Belgrade via Nis to Salonika and Sofiya, respectively. The use of these two vital supply arteries was denied to the German Army. Therefore the following precautionary steps had to be taken to ensure the uninterrupted flow of supplies to the Twelfth Army forces in Bulgaria:
1. Heavy truck transportation units at the disposal of the Army High Command, carrying capacity loads, were transferred to Romania and from there to Bulgaria.
A number of barges, loaded with a total of 10,000 tons of supplies, and a tanker were assembling at Vienna destined for Belgrade, where a supply base was to be established as soon as possible.
3. Another river fleets carrying 16,000 tons of rations and ammunition, was standing by on the Danube between Regensburg and Vienna. The vessels were destined for the German forces in Romania and were to sail down the Danube as soon as the waterway had been reopened to shipping.
Providing Second Army with the necessary supplies presented no particular problems and caused no delay in the launching of the operations. When surgical hospitals failed to arrive, for example, they were replaced by additional hospital trains.
The logistical planning was greatly facilitated by the establishment of a supply base near Vienna during the summer of 1940. Soviet political activities in the Balkans had prompted the Army High Command to stockpile large quantities of supplies at the gateway to southeastern Europe . The existence of this base made it possible to meet the sudden and unexpected demands of the Yugoslav campaign without shifting supplies from the interior of Germany, a step that would have delayed the operation considerably.
IV. The Assembly of Second Army
During the winter of 1940-41, Second Army headquarters in Munich had been responsible for training the divisions stationed in southern Germany and the former Czechoslovak territory. When Second Army headquarters was alerted for the Yugoslav attack, its training mission was assumed by Eleventh Army.
Toward the end of March 1941 no forces other than a few infantry divisions were available in Germany for immediate commitment. Those armored and motorized infantry divisions that happened to be in Germany at the time were in the process of activation, reorganization, or rehabilitation. The mobile divisions needed by Second Army therefore had to be drawn from France and the Russian border, and their transfer to the Balkans could easily have resulted in delays. The only available mountain division, whose employment was essential for the successful conduct of the Yugoslav campaign, had to be brought east from France. Similar difficulties were encountered in assembling the necessary GHQ units and artillery, engineer, and service troops. The following chart shows the problem involved in assembling the divisions assigned to Second Army:
Assembly of Second Army Units
Unit Stationed in Means of transportation Second Army HQ Staff Germany Organic. 8th Panzer Division France Railroad and Organic. 14th Panzer Division Russian border Railroad and Organic. 16th Motorized Inf. Div. France Railroad and Organic. 1st Mountain Division France Motor Transportation. 79th Infantry Division France Railroad. 101st Light Inf. Div Czechoslovakia Motor Transportation. 125th Infantry Division Germany Railroad. 132d Infantry Division Germany Railroad. 183d Infantry Division Germany Railroad.
The actual movements of these units took place in the following manner: Using organic transportation, Second Army headquarters moved from Munich to Radegund, near Graz, on 2 April. The XLIX Mountain Corps was expected to arrive in its assembly area on 4 April. After its transfer from France to Germany the 1st Mountain Division moved by motor transportation from Landaberg, northeast of Berlin, to Vienna. On 5 April the forward echelon of the division was ordered not to dismount in Vienna as previously planned, but to continue the movement to its assembly area near Klagenfurt, where it was to arrive by the evening of 8 April. However, the bulk of its combat elements did not get to Klagenfurt until 9 April, the eve of D-day, while most of the service troops joined the division piecemeal between 13 and 15 April, well after the start of operations.
Whereas LI Corps headquarters arrived in its assembly area in good time, the divisions under its command encountered many difficulties. The 132d and 183d Infantry Divisions had been ordered to entrain on 2 April. By 6 April about two-thirds of each division had detrained in Graz, and both were completely unloaded by 9 April. Meanwhile, a truck transportation regiment, then located in Paris, was ordered to proceed to Czechoslovakia from where it was to move the 101st Light Infantry Division to its assembly area. Advance elements of this division were to be in line by 9 April. However, icy roads delayed the movement to such an extent that the tail elements did not reach their destination until 15 April.
The efforts made to speed up the concentration of LII Infantry Corps were of little avail. By 11 April, after the attacks were well under way, the Army High Command was still in the dark as to when this corps, including the 79th and 125th Infantry Divisions, might
The German Campaign in Yugoslavia (Operation 25) (452K)
become operational. Eventually the former division was transferred to XLIX Mountain Corps, while the latter, remaining under the command of LII Corps, was held in reserve. It was 12 April when the first ten trains carrying the 79th Infantry Division pulled into the assembly area.
Only the assembly of XLVI Panzer Corps went according to schedule. The advance echelon of the 16th Motorized Infantry Division arrived in Vienna by rail on 8 April and immediately proceeded from there to the concentration area in Hungary by organic transportation. By the evening of 7 April, the 14th Panzer Division arrived in Nagykanizsa, while the 8th Panzer Division assembled its forces to the north of Lake Balaton. Although the snow had melted, the movements of all three divisions were hampered by heavy rains, and it was necessary to employ additional traffic control elements to avoid undue stoppages. However, when the lead elements of the 16th Motorized Infantry Division arrived in their assembly area on 9 April, the XLVI Panzer Corps was the only major Second Army command whose units were fully prepared to jumpoff on D-day.
I. The Air Bombardment of Belgrade
The Luftwaffe opened the assault on Yugoslavia by conducting a saturation-type bombing raid on the capital in the early morning hours of 6 April. (Map 4) Flying in relays from airfields in Austria and Romania, 150 bombers and dive-bombers protected by a heavy fighter escort participated in the attack. The initial raid was carried out at fifteen-minute intervals in three distinct waves, each lasting for approximately twenty minutes. Thus, the city was subjected to a rain of bombs for almost one and a half hours. The German bombardiers directed their main effort against the center of the city, where the principal government buildings were located.
The weak Yugoslav Air Force and the inadequate flak defenses were quickly wiped out by the first wave, permitting the dive-bombers to come down to roof-top levels. Against the loss of but two German fighters, twenty Yugoslav planes were shot down and forty-four were destroyed on the ground. When the attack was over, more than 17,000 inhabitants lay dead under the debris. This devastating blow virtually destroyed all means of communication between the Yugoslav high command and the forces in the field. Although some elements of the
general staff managed to escape to one of the suburbs, coordination and control of the military operations in the field were rendered impossible from the outset.
Having thus delivered the knockout blow to the enemy nerve center, the VIII Air Corps was able to devote its maximum effort to such targets of opportunity as Yugoslav airfields, routes of communication, and troop concentrations, and to the close support of German ground operations.
II. The Three-Pronged Drive on the Yugoslav Capital
Three separate ground forces converged on Belgrade from different directions. They were launched as follows:
1. First Panzer Croup (Twelfth Albany)
Early in the morning of 8 April, the First Panzer Group jumped off from its assembly area northwest of Sofiya. Crossing the frontier near Pirot, the XIV Panzer Corps, spearheaded by the 11th Panzer Division, followed by the 5th Panzer, 294th Infantry, and 4th Mountain Divisions, advanced in a northwesterly direction toward Nis. Despite unfavorable weather, numerous road blocks, and tough resistance by the Yugoslav Fifth Army, the 11th Panzer Division, effectively supported by strong artillery and Luftwaffe forces, quickly gained ground and broke through the enemy lines on the first day of the attack. The Yugoslav army commander was so greatly impressed by this initial German success that he ordered his forces to withdraw behind the Morava. This maneuver could not be executed in time because, as early as 9 April, the German lead tanks rumbled into Nis and immediately continued their drive toward Belgrade. From Nis northwestward the terrain became more favorable since the armored columns could follow the Morava valley all the way to the Yugoslav capital.
South of Paracin and southwest of Kragujevac Yugoslav Fifth Army units attempted to stem the tide of the advance but were quickly routed after some heavy fighting. More than 5,000 prisoners were taken in this one encounter.
Meanwhile, the 5th Panzer Division became temporarily stalled along the poor roads near Pirot. After the division got rolling again, it was ordered to turn southward just below Nis and cut off the enemy forces around Leskovac. When it became apparent that the Nis front was about to collapse, the 5th Panzer Division reverted to the direct control of Twelfth Army and joined the XL Panzer Corps for the Greek campaign.
[Figure 6. Prime movers towing heavy trucks along muddgy road]
On 10 April the XIV Panzer Corps forces were swiftly advancing through the Morava Valley in close pursuit of enemy units retreating toward their capital. On the next day the German spearheads suddenly drove into the southern wing of the withdrawing Yugoslav Sixth Army, which they overran during the early hours of 12 April. By the evening of that day the First Panzer Group tanks stood less than forty miles southeast of Belgrade. The two Yugoslav armies they had encountered were in such a state of confusion that they were no longer able to make any serious attempt to delay the German thrust or cut the German lines of communications that extended over a distance of roughly 125 miles from the point of entry into Yugoslav territory.
2. XLI Panzer Corps (Independent Force)
Timed to coincide with the armored thrust of the XIV Panzer Corps from the southeast, the XLI Panzer Corps drive led across the southeastern part of the Banat and toward the Yugoslav capital. This attack was spearheaded by the Motorized Infantry Regiment "Gross Deutschland," closely followed by the 2d SS Motorized Infantry Division. After crossing the frontier north of Vrsac, advance elements entered Pancevo on 11 April. Having meanwhile advanced to within about forty-five miles north of Belgrade, the main body of XLI Panzer Corps met with only isolated resistance on the following day as it raced toward the enemy capital.
3. XLVI Panzer Corps (Second Army)
When the Luftwaffe launched its attacks on 6 April, the German Second Army was just beginning to assemble its attack forces along the northern Yugoslav frontier preparatory to its projected jumped on 10 April. In an effort to improve their lines of departure, some of the Second Army units took advantage of the interim period by launching limited-objective attacks all along the frontier zone. The troop commanders had to keep their forces in check to prevent major engagements from developing prematurely, which might subsequently have impaired the army's freedom of action and jeopardized the conduct of operations.
The Army High Command was determined to seize intact the principal bridges in the XLVI Panzer Corps zone. Therefore, as early as 1 April, corps elements were ordered to capture the bridge at Bares and the railroad bridge about ten miles northeast of Koprivoica by a coup de Ann.
By early evening of 6 April, the lack of enemy resistance and the overall situation seemed to indicate that the Yugoslavs would not make
a concerted stand along the border and the XLVI Panzer Corps was therefore ordered to establish bridgeheads across the Mura and Drava at Mursko Sredisce, Letenye, Zakany, and Barcs. The few local attacks carried out by the corps sufficed to create dissension in the enemy ranks. There was a high percentage of Croats in the Yugoslav Fourth Army units that were responsible for the defense of this area. Croat soldiers mutinied at several points of the Drava salient, refusing to resist the Germans whom they considered as their liberators from Serbian oppression. When strong German forces crossed the Drava bridge at Bares on the morning of 10 April and broke out of the previously established bridgeheads, the disintegration of the opposing Yugoslav forces had reached an advanced stage. Supported by strong air forces, the 8th Panzer Division, followed by the 16th Motorized infantry Division, launched the XLVI Panzer Corps thrust to Belgrade by driving southeastward between the Drava and Sava Rivers. By the evening of 10 April forward elements of the 8th Panzer Division, having met with virtually no resistance, reached Slating despite poor roads and unfavorable weather. Enemy pockets were quickly mopped up and the division drove on in the direction of the capital via Osijok, where the roads became even worse.
That the plight of the enemy was becoming more and more desperate could be gathered from the following appeal that General Simovic broadcast to his troops:
All troops must engage the enemy wherever encountered and with
every means at their disposal. Don't wait for direct orders from
above but act on your own and be guided by your judgment, initiative, and conscience.
On 11 April the 8th Panzer Division reached the Osijek region, while the 16th Motorized Infantry Division farther back was advancing beyond Nasice. Numerous bridge demolitions and- poor roads retarded the progress of both divisions, whose mission it was to attack the rear of the Yugoslav forces that faced XIV Panzer Corps, and to establish early contact with the First Panzer Group.
At 0230 on 12 April, the 8th Panzer Division entered Mitrovica after two vital bridges across the Sava had been captured intact. The division continued its thrust with the main body advancing toward Lazarevac, about twenty miles south of Belgrade, which was the designated link-up point with First Panzer Group.
On the afternoon of 12 April, the XLVI Panzer Corps received new orders. According to these, only elements of the 8th Panzer Division were to continue their eastward drive to seize and secure the Sava bridge near the western outskirts of Belgrade. At 1830 the main body
of the division turned southeastward and moved in the direction of Valjevo to establish contact with the left wing of First Panzer Group southwest of Belgrade. Simultaneously, the 16th Motorized Infantry Division, which had been trailing behind the 8th Panzer Division, turned southward, crossed the Sava, and advanced toward Zvornik. Thus both divisions were diverted from their original objective, Belgrade, in order to participate in the subsequent drive on Sarajevo.
Meanwhile, both the Second Army and the Army High Command were anxiously awaiting news of the fall of Belgrade. Of the three converging armored forces, XLI Panzer Corps was last reported closest to the capital, having reached Pancevo on the east bank of the Danube about ten miles east of the city. South of Belgrade resistance stiffened as the 11th Panzer Division, spearheading the First Panzer Group forces, neared the capital.
4. The fall of Belgrade
Since three separate attack forces were converging on Belgrade simultaneously, the Army High Command was not immediately able to determine which force was the first to reach the enemy capital. Toward early evening of 12 April, SS-Obersturmfuehrer (1st Lt.) Klingenberg of the 2d SS Motorized Infantry Division, finding all Danube bridges destroyed, took an SS patrol across the river in captured pneumatic rafts. The patrol entered the city unmolested, and at 1700 hoisted the Nazi flag atop the German legation. About two hours later the mayor of Belgrade officially handed over the city to Klingenberg who was accompanied by a representative of the German Foreign Ministry, previously interned by the Yugoslavs.
At Second Army headquarters, no word from the 8th Panzer Division elements, which were last reported approaching the western outskirts of Belgrade, had been received for twenty-four hours. Finally, at 1152 on 13 April the following radio message came through from the operations officer of the division:
During the night the 8th Panzer Division drove into Belgrade, occupied the center of the city, and hoisted the Swastika nag.
However, since better communications had existed between Second Army and First Panzer Group, the following flash was received shortly before the 8th Panzer Division message came in:
Panzer Group von Kleist has taken Belgrade from the south. Patrols of Motorized Infantry Regiment "Gross Deutschland" have entered the city from the north. With General von Kleist at the head, the 11th Panzer Division has been rolling into the capital since 0632.
Thus the race for Belgrade ended in a close finish with all three forces reaching their objective almost simultaneously. With the fall
[Figure 7. German patrol returning from a raid across the Yugoslav border]
of the city, the First Panzer Group was transferred from the Twelfth to the Second Army, while the XLVI Panzer Corps was placed under the direct command of the panzer group for the next phase of the operation-the pursuit and final destruction of the remnants of the Yugoslav Army.
III. Secondary Attacks
Before and during the main drive on Belgrade a series of secondary attacks and small unit actions took place across the Austrian-Yugoslav frontier, where the terrain was unsuitable for motorized units. The following actions were of particular significance:
1. The "Feurzauber" Probing Attacks
Under the code designation "Feurzauber," units composed of cadre personnel and recently inducted trainees were organized into several waves of special assault troops. The elements comprising the first wave consisted of four battalion staffs commanding nine rifle companies, two mountain artillery batteries, one self-propelled medium artillery battery, two mountain engineer platoons, four antitank companies, and three signal and four bicycle platoons. Additional waves were subsequently formed, involving altogether about two-thirds of a mountain training division plus some attached specialist troops.
Originally these units were merely to reinforce the frontier guards and cover the gradually assembling Second Army forces along the southern border of Carinthia and Styria. This purely defensive mission, however, did not satisfy the aggressive commanders of the special assault units. Between 6 and 10 April, they took upon themselves to conduct numerous raids deep into enemy-held territory and to seize and hold many strong points along the border, thereby contributing to the rapid success of the offensive proper.
The first wave of assault units moved south from Graz in the direction of the Yugoslav border on 27 March. One of them, designated "Force Palten" after the captain in command, was assembled near Spielfeld during the first days of April. Its original mission was to secure the frontier and the vital bridge across the Mura near Spielfeld. However, on the evening of 5 April the force started to attack bunkers and enemy-held high ground across the frontier. By the morning of 6 April several hills had been taken, and scouting patrols probing deep into the bunker line south of Spielfeld made contact with the enemy. They determined the enemy's strength and disposition in the outpost area, and then broke contact. Most of the high ground remained in German hands as the enemy failed to counterattack. Then, toward 1600, mountain engineers destroyed isolated enemy bunkers without any preparatory artillery fire.
On 8 April, Captain Palten decided to personally lead a group of his raiders toward Maribor. He undertook this mission against orders from higher headquarters and despite the fact that virtually all bridges along the route of advance had been blown. Since there was hardly any enemy interference, troops and equipment could be ferried across the Pesnica stream on pneumatic rafts. The vehicles had to be left behind, and the men were forced to carry their equipment the rest of the way.
After forming raiding parties on the south bank of the stream, Captain Palten continued to move southward. During the evening he entered Maribor at the head of his force and occupied the town without opposition. Much to their disappointment, the raiders were ordered to withdraw to the Spielfeld area, where they had to sit out the remainder of the Yugoslav campaign performing guard duty at the border. Losses incurred by Force Palten were one killed and two wounded, while they captured more than 100 prisoners and much booty.
2. LI Corps
On 6 April the ELI Corps crossed the Yugoslav border at Murk and Radkersburg and seized both bridges across the Drava intact. During these probing attacks the 132d Infantry Division occupied the Sejanska stream and the 183d Infantry Division took 300 prisoners. A bicycle detachment of the latter entered Murska Sobota without encountering resistance. Since the Yugoslavs were giving ground all along the line, the corps wanted to exploit the situation. The Second Army, however, felt compelled to order both divisions to hold in place and consolidate their newly won bridgeheads. The two divisions would have to wait until their remaining elements had detrained in the assembly areas.
During the following three days the LI Corps expanded its bridgeheads, the 132d Infantry Division occupying Maribor and the 183d probing beyond Murska Sobota. Air reconnaissance reports indicated that the Yugoslav Seventh Army forces employed in this sector were withdrawing southward along the narrow mountain roads leading to Zagreb. Apparently only a thin security screen had been left in place to maintain contact with the German forces in the bridgeheads.
The Second Army thereupon ordered LI Corps to form flying columns composed of motorized elements and pursue the retreating Yugoslav forces in the direction of Zagreb. On 10 April cold winds and intermittent snowstorms hampered the movements of the advancing Germans, and flood waters interrupted the crossings at Maribor during the day. After regrouping its forces south of the
Drava the LI Corps resumed its advance toward Zagreb at 0600 on 11 April. Plodding through difficult terrain during the afternoon, forward elements reached the southern exit of the mountain range northwest of the city by evening. A bicycle troop of the 183d Division wheeling eastward had, meanwhile, taken Varazdin, where it captured a Serb brigade, including its commanding general.
3. XLIX Mountain Corps
On 6 April, while the 1st Mountain Division was still on the approach march, the 538th Frontier Guard Division, stationed along the northwestern part of the Slovenian border, succeeded in seizing important mountain passes, hills, and tunnels in Yugoslav territory. During the night of 9-10 April the combat elements of the 1st Mountain Division, which had detrained only a few hours earlier, began to cross the frontier near Bleiburg. Advancing in the general direction of Celje the division spearheads stood about twelve miles northwest of the town by nightfall. After exhausting marches and some hard fighting the 1st Mountain Division took Celje on 11 April. Emissaries of the newly formed Slovenian Government asked the corps commander for a cease-fire. In anticipation of just such developments, Hitler had previously authorized field commanders to accept the surrender of individual units.
4. 14th Panzer Division (XLVI Panzer Corps)
Early on the morning of 10 April, with dive-bombers clearing the route of advance, the 14th Panzer Division of XLVI Panzer Corps, split into two armored forces, broke out of the Drava bridgehead and advanced southwestward toward Zagreb, the state capital of Croatia. This attack preceded the XLVI Panzer Corps main attack toward Belgrade and was intended as a diversion.
Although large enemy concentrations had been spotted in front of the division, air reconnaissance revealed that these forces were rapidly withdrawing westward toward Zagreb. Though fierce at first, enemy resistance soon crumbled as German tanks came closer to their objective. However, extremely cold weather and snow-covered roads hampered progress to some degree. By 1930 on 10 April the lead tanks of the 14th Panzer Division reached the outskirts of Zagreb, after having covered a distance of almost 100 miles in one day.
In some instances Croat troops refused to fight, abandoned their weapons, deserted their positions, and either surrendered or simply went home. One German regiment surprised an enemy unit which was still in garrison and not yet fully mobilized. A regimental officers' party just in progress was interrupted only long enough to consummate a quick surrender, whereupon the festivities continued as though nothing unusual had happened.
[Figure 8. Man and beast working together to pull vehicles out of the mud]
So rapid was the advance of the division that its radio communications with corps and army were temporarily interrupted. Reconnaissance aircraft had to be dispatched to ascertain its exact location and chart its progress. When the 14th Panzer Division entered Zagreb from the northeast it was welcomed by a wildly cheering pro-German populace. During the drive on the city more than 15,000 prisoners were taken. Among the 300 officers were twenty-two generals, including the commanders of First Army Group and Seventh Army.
On 11 April the newly formed Croatian Government called on its nationals to cease fighting and requested that they be immediately released by the Yugoslav Army. During the evening hours the first LI Corps elements entered Zagreb from the north and relieved the 14th Panzer Division.
IV. Italian and Hungarian Operations
The favorable course of the military events along its front led the German Second Army to offer its assistance to the Italian Second Army assembling along Yugoslavia's western border. On the early morning of 11 April the Germans were informed that the Italian V, VI, and XI Corps would be ready to attack toward 1200. To speed up the Italian advance and consummate the encirclement of the Yugoslav Seventh Army forces in the Ljubljana Basin, the German XLIX Mountain Corps was to conduct the diversionary attacks in the north while 14th Panzer Division forces were to cut the enemy's route of withdrawal. As a preparatory step the German Fourth Air Force attacked Yugoslav columns and troop concentrations in the Ljubljana area. When the Italian forces finally jumped off, they encountered little resistance from the Yugoslavs, who were attempting to withdraw southeastward. A great number of prisoners and much booty were captured as entire divisions surrendered. About 30,000 Yugoslav troops concentrated near Delnice were waiting to surrender to the Italians who were moving southeastward in the direction of the Dalmatian coast.
On 12 April elements of the 14th Panzer Division linked up with the Italians at Vrbovsk. The line Novo Mesto-Slunj-Bihac-Livno was designated as the boundary between the German and Italian Second Armies south of the Sava. Occupation of the territory west of this line was assigned to the Italians. However, for the time being the German units on the extreme right wing of XLIX Mountain Corps were authorized to operate in the Italian zone.
Upon moving its command post to Maribor on 11 April, the German Second Army headquarters received a message from the Hungarian Third Army by which it was notified that Hungarian troops
were crossing the Yugoslav frontier north of Osijek and near Subotica. On the next day the Hungarians pursued the retreating Yugoslav First Army and occupied the area between the Danube and Tisza Rivers, meeting virtually no resistance.
V. The Final Drive on Sarajevo
After the collapse of the border defense system and the fall of Belgrade the Yugoslav Army leaders had hoped to withdraw to the mountain redoubt in the interior of Serbia, where they intended to offer prolonged resistance. Fully aware of the Yugoslav intentions, General von Weichs, the Second Army commander, decided to launch and maintain a vigorous pursuit of the enemy forces withdrawing in the general direction of Sarajevo. Speed was now of the essence since the German Army High Command intended to pull out and redeploy as soon as practicable the motorized and armored divisions that had to be refitted for the Russian campaign.
As early as 12 April both the XLIX and LI Corps had closed up and regrouped their forces along the Sava River. Sarajevo, located in the heart of Yugoslavia, was to be the focal point upon which the German forces were to converge. Accordingly, Second Army reorganized its forces into two separate pursuit groups. Under the command of the recently arrived LII Infantry Corps headquarters, the western group consisted of four infantry divisions under the XLIX and LI Corps as well as the 14th Panzer Division, the formation that was to spearhead the drive on Sarajevo from the west. The eastern pursuit force, under the command of the First Panzer Group, was composed of six divisions, with the 8th Panzer Division leading the drive toward Sarajevo from the east. The Fourth Air Force, continuing to operate in support of the ground operations, was ordered to neutralize the anticipated enemy troop concentrations in the Mostar-Sarajevo sector.
On the afternoon of 13 April Second Army moved its command post to Zagreb to facilitate communication with the two pursuit groups and direct the mopping-up phase of the campaign from this central location. The boundary between the German Second and Twelfth Armies was the line extending laterally across Yugoslavia from Sofiya via Prizren up to and along the northern border of Albania.
By the evening of 13 April there was no longer any semblance of enemy resistance in front of XLIX and LI Corps. The main body of the German forces reached the Kupa River and some elements were quickly put across. The 14th Panzer Division, meanwhile, sped southeastward toward Sarajevo. As the division approached its ob-
[Figure 9. German Mark III tank advancing through the mountain pass protected by flak]
jective, reports began to circulate that open hostilities had broken out between Serbs and Croats in Mostar. German planes were quickly diverted to this area where they blasted Serb troop concentrations for three hours. By 14 April the fighting between the Serb and Croat factions had gained momentum and had spread throughout Dalmatia. On that day the 14th Panzer Division reached Jajce, approximately fifty miles northwest of Sarajevo, while forward elements of the LI Corps, attempting to keep up with the armor, arrived at the Una after strenuous marches and established several bridgeheads across the stream.
In the zone of the eastern group, one armored division combed out the sector south of Belgrade, while two infantry divisions cleared the industrial region in and around Nis. The 8th Panzer Division led the way southwestward toward Sarajevo, closely followed by two motorized infantry divisions which were driving hard toward the heart of Yugoslavia, one via Zvornik, the other from Uzice. Among the vast amount of booty were seventy-five enemy aircraft still intact on the ground. During the operations on 14 and 15 April, prisoners were taken by the thousands. North of Nis the Germans captured 7,000; in and around Uzice, 40,000; around Zvornik 30,000 more; and in Doboj another 6,000.
On 15 April both pursuit groups of Second Army closed in on Sarajevo. As two panzer divisions entered the city simultaneously from. west and east, the Yugoslav Second Army, whose headquarters was in Sarajevo, capitulated. Leaving only security detachments in the city to await the arrival of the infantry forces, both divisions continued to race southward in close pursuit of fleeing enemy remnants.
VI. Armistice Negotiations
In view of the hopelessness of the situation, the Yugoslav command decided to ask for an armistice and authorized the commanders of the various army groups and armies to dispatch truce negotiators to the German command post within their respective sectors. However, those from Yugoslav Second and Fifth Armies who asked for separate cease-fire agreements on 14 April were turned back by the German commanders because by that time only the unconditional surrender of the entire Yugoslav Army could be considered as a basis for negotiations.
Late on the evening of 14 April, a representative of the Yugoslav Government approached the First Panzer Group headquarters and asked General van Kleist for an immediate cease-fire. When the Army High Command was advised of this turn of events, it desig
nated the Second Army commander, General von Weichs, to conduct the negotiations in Belgrade.
During the afternoon of the following day von Weichs and his staff arrived in Belgrade and drew up the German conditions for an armistice based on the unconditional surrender of all Yugoslav forces. The next day a Yugoslav emissary arrived in the capital, but it turned out that he did not have sufficient authority to negotiate or sign the surrender. Therefore, a draft of the agreement was handed to him with the request that competent plenipotentiaries be sent to Belgrade without delay in order to avoid unnecessary bloodshed. To expedite matters, a plane was placed at his disposal.
The armistice was concluded and signed on 17 April. (general von Weichs signed for the Germans, with the Italian military attache in Belgrade acting on behalf of his country. The Hungarians were represented by a liaison officer who, however, did not sign the document since Hungary was technically "not at war with Yugoslavia." Foreign Minister Cincar-Marcovic and General Milojko Yankovic signed for the Yugoslavs. The armistice became effective at 1200 on 18 April 1941, just twelve days after the initial German attack was launched.
The losses sustained by the German attack forces were unexpectedly light. During the twelve days of combat the total casualty figures came to 558 men: 151 were listed as killed, 392 as wounded, and 15 as missing in action. During the XLI Panzer Corps drive on Bel grade, for example, the only officer killed in action fell victim to a civilian sniper's bullet.
The Germans took some 254,000 prisoners, excluding a considerable number of Croat, German, Hungarian, and Bulgarian nationals who had been inducted into the Yugoslav Army and who were quickly released after screening.
The campaign in Yugoslavia must be considered an improvisation, since it was launched before the attack forces were fully assembled. This fact should be constantly borne in mind when evaluating the experiences gained.
In reviewing the operation the following facts stand out:
The tactical principles set forth in German Field Service Regulations proved their worth when properly applied.
2. The employment of motorized divisions in alpine terrain against an inferior defense force was instrumental in achieving speedy success.
3. The German tanks and trucks proved capable of negotiating virtually every type of terrain.
II. Coalition Warfare
During the Yugoslav campaign the German command was confronted by the problems of coalition warfare for the first time. It became obvious from the very start that the German units would have to be the driving spirit and carry the brunt of the fighting during the operations. The participating allied and satellite forces achieved success only when they were under German command.
Both commanders and troops of the Italian Second Army lacked aggressiveness and initiative. Moreover, the Italian command demonstrated little tactical know-how and failed to comprehend German strategic concepts. Its intelligence system was poorly developed and often tended to overestimate enemy strength and capabilities. During the entire campaign the Italians, as well as the Hungarians, displayed great reluctance to attack until the enemy had been soundly beaten and thoroughly disorganized by the (Germans.
The assembly of the Second Army forces, based on the premise that the attack would not be launched until 10 April, proceeded according to schedule. However, with the Twelfth Army's attack starting on 6 April, Second Army was forced to take action while still in the process of assembling. In planning the assembly this development was not anticipated; the sequence in which the forces arrived within their concentration areas was ill-conceived in many instances. To assure a more efficient assembly of forces in a similar situation, the following points should be borne in mind:
- In establishing the march sequence for any troop movement it is vital that the unit commander concerned be consulted so that the forces necessary for immediate commitment have precedence over the technical support elements.
- It is imperative that those command echelons directly responsible for the conduct of operations, such as army and corps forward headquarters, together with their signal, reconnaissance, and, especially, engineer units, be the first to arrive in the assembly area.
- Within a division, the reconnaissance battalion and engineer elements should constitute the lead echelon along with the division command echelon, the signal battalion, and at least one regimental headquarters, including its signal platoon.
IV. Other Organizational and Tactical Improvisations
The Yugoslav campaign must be considered primarily as a series of operations against river lines and in mountainous terrain. In both instances, independent combined-arms teams with missions of seizing key bridges and hills proved effective and successful.
The infantry divisions that had to fight their way through mountainous terrain in northwestern Yugoslavia accomplished their missions relatively well. It would have been advantageous, however, if the divisions had been more familiar with the peculiarities of mountain warfare. Advance detachments played an important role, but were only formed when the need arose, and again disbanded once their specific mission was accomplished.
After the initial penetrations had been achieved, powerful armored wedges exploited the situation by breaking through at various points and swiftly moving deep into the enemy rear. It was here that German motorized equipment surpassed all expectations by covering great distances with lightning speed over primitive, winding roads and through narrow, treacherous mountain passes. Road and weather conditions, especially in the mountains, demanded the careful organization of march columns, and the proper employment of traffic control units. There can be no doubt that it was the rapid thrusts of the mechanized columns across the mountains that broke the back of enemy resistance and spelled the early doom of the Yugoslav Army.
As during earlier campaigns in World War II, the German superiority in armor and air power led to the quick conclusion of operations. Although the German General Staff planners had been well aware of the deficiencies and weaknesses of the Yugoslav Army, they were greatly surprised that the campaign could be concluded within so short a time.
I. Yugoslav Military Unpreparedness
What were the causes that led to this unexpectedly rapid success? Surely the Yugoslav high command must have expected German armed intervention as an aftermath of the coup d'etat For one thing the German Army was not actively engaged in any other theater of operations at that time. Furthermore, the growing concentration of German forces in Bulgaria should have been a clear warning that
[Figure 10. Disabled Yugoslav tank]
Hitler had aggressive designs on the Balkans. The campaigns of 1939 and 1940 should also have taught the Yugoslavs that German operations were invariably spearheaded by coordinated efforts of Luftwaffe and panzer units.
The idea of completely stopping a force so vastly superior in men and materiel could of course not have been entertained. However, sufficient resistance could have been mustered to gain time to permit allied forces to come to Yugoslavia's aid. The mountainous terrain in the Balkans gives the defender a certain advantage over a highly mechanized attack force. That Yugoslav defenses should have been better prepared is quite obvious. Some of the artificial obstacles encountered in the German Second Army zone indicated that efforts in that direction had been made, but were either insufficient or came too late.
When the German forces struck, the mobilization and concentration of Yugoslav defense forces had hardly begun. Instead of massing their forces around strategic points and behind natural terrain barriers in an effort to conserve strength and operate along interior lines of communication, the Yugoslav command chose to scatter its forces and spread them along the entire perimeter of the country's frontier. Thus, by attempting to hold everywhere, the Yugoslavs lost everything.
II. Internal Disunity
The lack of fighting spirit among major elements of the Yugoslav Army was equally decisive. Almost from the outset this deficiency became particularly obvious in the Second Army zone. Although it had been common knowledge that considerable tension existed within Yugoslavia, the Germans were surprised to see the inroads that the spirit of revolt had made on the national unity of the country. There can be little doubt that the rift between the Serbs and Croats played a major role in the rapid collapse. Whereas the Serbs vigorously opposed cooperation with Germany, as demonstrated by the uprising on 27 March, the Croat element of the population thought it wiser to compromise with Hitler than to resist in the face of tremendous odds. This feeling was naturally also shared by the Croats in the Army. A number of Croat officers even went to the extreme of committing acts of treason. In one such instance, an air force officer flew from Belgrade to (Iraz as early as 3 April and handed over to the Germans the highly classified list of airfields where the Yugoslav planes were dispersed. Thus, when the Luftwaffe struck these fields during the initial attack wave, it virtually wiped out what little Yugoslav air power there was.
In the ground fighting, shortly after the Germans attacked, entire Croat units simply threw away their weapons and quit. In some instances, Croat officers led their men in organized attacks against Serb elements that ware actively resisting the invaders. On 8 April, Croat troops openly revolted in Vinkovci, the main railroad junction along the vital Belgrade-Zagreb line. They launched a concerted attack against the headquarters of First Army Group and held as prisoners its commander with his entire staff until they were rescued by loyal Serb troops. Such occurrences were not unusual and happened in other sectors as well.
III. German Propaganda
German propaganda efforts naturally took full advantage of this open rift between Serbs and Croats. The constantly repeated official line was that Germany and Italy desired the creation of an independent state of Croatia and that the military operations were being conducted only against the Serbs. However, when Hitler was first told of the open animosity among the various ethnic factions in Yugoslavia, he is said to have remarked: "That is none of our business. If they want to bash each others' heads in, let them go ahead."
IV. Seeds of Unrest
The Germans, however, were soon to discover that, despite the official cessation of hostilities, many areas of Yugoslavia were far from pacified. The lack of resistance encountered during the brief military operations led the Germans to grossly underestimate the true fighting spirit of the Yugoslav people. That they were mistaken was clearly revealed during the ensuing years. The Yugoslavs' will to fight, squashed during the campaign of 1941, soon found outlet in widespread resistance movements. Operating from their sanctuaries in the mountains, Serbs, Croats, Slovenes, and other ethnic groups united their efforts to harass and plague the German and Italian occupation forces.
In a letter Mussolini wrote to Hitler on 29 December 1941, the former stated with reference to Yugoslavia:
Before next spring every nucleus of insurrection must be wiped out or else we run the risk of having to fight a subsidiary war in the Balkans. The first territory to be pacified is Bosnia, then Serbia and Montenegro. The military operations must be conducted with great determination and must lead to a real and complete disarmament of the population, this being the sole guarantee I for avoiding surprise in the future. For this purpose our military forces must cooperate according to a common plan to prevent duplication of effort and achieve the desired result with a minimum of manpower and materiel.