Sophistication of U.S. Army

Communications in Vietnam

Whereas the years from 1962 to 1967 were devoted to building the communications foundation in Vietnam, 1968 and 1969 were years of completion and sophistication. During that period the huge Integrated Wideband Communications System was finished. The telephone and message networks in Vietnam were further integrated and consolidated. For the first time, modern automatic switching equipment for both voice and message traffic was introduced into a combat zone.

Completion of the Integrated Communications System

The final links of Phases I and II of the Integrated Wideband Communications System were completed in the first two months of 1968. Their completion marked a communications milestone, extending high quality, multichannel communications throughout Vietnam: north to Hue, south to major cities in the Mekong Delta, and westward into Thailand. The fact that these two phases of the wideband system were completed and cut to traffic at this time had extreme combat significance. Many critical mobile assets could now be relieved from their interim service in the long-lines system and could be transferred to the north in support of the heavy troop buildup and unit relocations within I Corps Tactical Zone. The Tet offensive and the massing of enemy troops in the Demilitarized Zone and in the area of the Khe Sanh combat base had led to the strengthening of I Corps Tactical Zone.

Construction and installation at the new sites of Phase III, the final phase of the integrated long-lines system, were underway at the outset of 1968 and continued through the perilous weeks of the Tet offensive. Work on the new Phase III links and on system improvements progressed steadily, and by the end of the year all but one of the twenty-six links and upgrades had been completed and put into service. The uncompleted link was between Qui Nhon and Nha Trang.


Picture: "... Hold Yer Hats Fellas... Here Comes Another One Of The Signal Brigade's Modern, Sophisticated Communications Systems'..."

This last link of Phase III was accepted and put to traffic in January 1969. After four and a half years of effort and at a cost of approximately $235 million, the most massive undertaking in the history of the Army Signal Corps was finally finished, constituting throughout South Vietnam and Thailand the fixed-station, commercial-quality Integrated Wideband Communications System. (Map 7)

One final addition to the civilian contract for the wideband system was awarded in March 1968 for the provision and installation of four transportable, line-of-sight, microwave terminals. These transportable facilities had all the technical control capabilities and high channel capacity of the fixed wideband stations, plus the very distinct advantage that they could be moved if needed elsewhere. The first of these microwave terminals to be put into full operation was at Dong Ha, just a few kilometers south of the Demilitarized Zone. On 20 April 1969 this terminal linked with the fixed-station terminal at Quang Tri. Work was continuing, mean­while, on the three other transportable facilities being installed at Di An, a few miles north of Saigon, at Sa Dec, in the delta, and at Dong Ba Thin, near Cam Ranh Bay. All these facilities were operational by July 1969.


Map 7: Integrated Wideband Communications Systems, 1969


Integration of Defense Communications

In November 1968, the Department of Defense redesignated its telecommunications systems in Southeast Asia as the Integrated


Communications System, Southeast Asia. This move involved more than just another complicated name. Now one single system incorporated previously distinct elements: the large fixed-station wideband system, the undersea cable system that looped around the coast of Vietnam to Thailand, and a considerable number of mobile line-of-sight and tropospheric scatter radio facilities, supplementing and extending the terminal points, or tails, of the Defense Communications System in Vietnam.

Soon after the completion of the fixed wideband system and the establishment of the over-all integrated system, numerous transportable combat communications links were released, and, since they were no longer needed to support the long-lines network, they were at once relocated to provide support for combat operations. A most critical and immediate need was the major reconfiguration of the communications in I Corps Tactical Zone. Reconfiguration was completed in early January 1969, thereby releasing U.S. Air Force tropospheric scatter systems, which had been "temporarily" deployed to Vietnam in 1966 when it was apparent that the rapid influx of troops was surpassing the limited capability of the long-lines system. The Air Force equipment, however, had remained in place and in use for three years, until the back­bone system attained full capacity in 1969.

Similar "purging" of the integrated long-lines system was soon accomplished throughout the rest of Vietnam; the result was the release of considerable quantities of mobile signal equipment that had been previously committed, as an interim stopgap measure, to the support of the Defense Communications System. The Integrated Communications System, Southeast Asia, became stable in mid-1969, thus yielding the fruit of much labor.

Automatic Message Switching-Another First

The activation of automatic message and data switching centers at Phu Lam and Nha Trang in early 1968 introduced the world­wide Automatic Digital Network into Vietnam. The Phu Lam switching center of this network began passing traffic in March 1968. The flow of traffic through the Phu Lam switching center wrote a new chapter in communications history: the multimillion dollar switch was the first of its kind ever to be installed in a combat zone in sight of Viet Cong patrols. A similar automatic switch was activated at Nha Trang on 3 June 1968. Subscriber message terminals to serve the U.S. forces were activated as fast as the equipment was available. At the end of 1968, the Phu Lam switch was serving twenty-eight subscriber terminals with an average daily


Photograph: Checking A Console At Phu Lam Automatic Message Switching Center

CHECKING A CONSOLE AT PHU LAM AUTOMATIC MESSAGE SWITCHING CENTER. White rubber-soled shoes were required in dust-free, temperature-controlled building necessary for equipment.


traffic volume of 37,000 messages. Nha Trang, serving nineteen subscribers, was handling more than 25,000 messages daily.

The 1st Signal Brigade was charged with the responsibility of operating and maintaining not only the two automatic switching centers based in Vietnam, but also all Army subscriber terminals that were connected to the big automatic switches. The digital network provided the primary trunking for the Defense Department's integrated automatic and nonautomatic message network in Vietnam. At its peak, the system handled in excess of 100,000 messages per day, with the Army portion of the network encompassing some eighty-six communications centers with twenty-five automatic digital terminals. Within this count were the automatic terminals provided to the combat divisions throughout the country. From Camp Eagle in the north, near the city of Hue, home of the 101st Airborne Division, to Cu Chi in III Corps Tactical Zone, home of the 25th Infantry Division, communicators from the 1st Signal Brigade operated low-speed, 100-words-per-minute automatic terminals. Usually mounted on vans but sometimes installed in a fixed facility, these terminals provided the division commander with direct worldwide access for message communications.

In only two years, from the activation of the Phu Lam automatic switching center in 1968 to late 1970, the automatic message system in Vietnam expanded to meet the requirements of centralized control and accurate, high-speed communications. The impact of the Automatic Digital Network on record communications in a war zone was immense because for the first time U.S. Forces possessed a reliable and accurate high-speed method of ordering am­munition and repair parts, reporting casualties, and requesting replacements.

In late 1969 some of the last necessary refinements were made on the message communications system in Vietnam. The older manual message relay facilities at Phu Lam and Da Nang were phased out of service. The Nha Trang relay had been relegated to the less important role of minor relay in December 1968. These re­lays had carried the burden of message communications in Vietnam and served as the gateway stations to the rest of the world since the early 1960s. But manual tape relays proved to be too slow for our modern army in combat. The inevitable arrival of automatic switching in the combat zone marked the end of an era in military communications, the end of the reliance on torn-tape relay as the basis for message communications, and another step in our progress to writer-to-reader secure communications.


Tandem Switches-An Ultimate

At the end of 1968 the Southeast Asia Automatic Telephone Service was nearing completion, and the many years of operator­assisted long-distance telephone calls were coming to an end. In November of that year the first automatic long-distance telephone switching center at Bang Pla, near Bangkok, Thailand, was completed and cut over to service. The remaining switching centers in Vietnam and Thailand were in various stages of completion. On 22 February 1969 the Can Tho automatic switch was completed. Its cutover was followed by cutovers of centers at Korat, Thailand, in :March, and at DA Nang in mid-April 1969. The telephone switching centers at Tan Son Nhut and Nha Trang were completed at the end of July. Installation continued at the centers of the remaining sites at Pleiku, Vung Chua Mountain near Qui Nhon, and Ubon, Thailand. These last three switches became operational by the end of 1969, thus completing the long-distance direct dial system for Southeast Asia.

The nine switches comprising this system were connected to some fifty-four automatic dial telephone exchanges of the Army, Navy, and Air Force in Vietnam and Thailand, allowing selected subscribers and all dial telephone exchange operators to dial directly any telephone subscriber in Southeast Asia, and giving access into the worldwide Automatic Voice Network. The U.S. automatic dial telephone exchanges in Vietnam, which had access to the long-distance system, were by themselves processing over 1,000,000 telephone calls each day in 1969. (Map 8)

Another critical and essential long-distance telephone service was in the area of command control. In the summer of 1967 the 1st Signal Brigade installed small automatic telephone exchanges, dubbed "emergency action consoles," at the command operations centers of the U.S. Military Assistance Command in Saigon and of U.S. Army, Vietnam, at Long Binh. These consoles provided automatic telephone service to the essential subscribers in Saigon and Long Binh. In addition, the control elements of the subordinate commands, down to separate brigade levels, were connected to both emergency action consoles by separate long-distance telephone circuits.

The Signal Soldier

The growth of U.S. and Free World Military Assistance Forces in the Republic of Vietnam from 1962 to 1968 brought with it problems concerning the personnel needed to operate and main-


Map 8: Automatic Dial Telephone Exchanges, 1969


tain the widespread communications facilities. The problems came from many sources, among them the lack of certain select specialists and the introduction of new equipment into Vietnam when the operators had no previous training in the United States. Although


assigned strengths lagged behind authorized figures throughout the entire U.S. Army in Vietnam, I will discuss here only those man­power problems that were peculiar to the U.S. Army Signal Corps operating in Vietnam and the actions that were taken to ease these problems.

Operation and maintenance difficulties often arose when new equipment was introduced into Vietnam before the Army's schools in the United States could provide trained men. This situation forced the operating signal units to take soldiers away from their primary and essential duties and either give them on-the-job training with the new equipment or send them to the 1st Signal Brigade's Army Training Facility at Long Binh for formal instruction. Typical examples of such equipment were the commercial dial switching gear of the telephone network and the data transmission terminals associated with the Automatic Digital Network.

One of the most critical manpower shortages was in the specialty of communications cable-splicer. Long before the communications expansion in Vietnam, the decision had been made by the U.S. Army to discontinue cable-splicing as a course of instruction and instead to send Army students to the joint course conducted by the Air Force at Sheppard Air Force Base in Texas. As heavy cable construction became routine in all of the large Vietnam base camps, it was apparent that the numbers graduating from this joint course could not meet the requirements of the U.S. Army, Vietnam, for trained splicers. The shortage was largely alleviated by introducing a cable-splicing course at the 1st Signal Brigade's Army Training Facility in Vietnam. While this method produced a journeyman-soldier capable of beginning work on heavy cable construction projects and making repairs, the time he spent at the school decreased the time left in the soldier's 12-month tour in which his new-found skills could be put to use. We also had difficulties in other fields. Many microwave, tropospheric scatter, radar, computer, and cryptographic specialists arriving in Vietnam needed additional training before they could perform their tasks in an acceptable manner. These men were given refresher courses at the brigade's training facility.

Another area of concern was that signal personnel arrived in Vietnam from two different sources. Signal officers and men for the 1st Signal Brigade were requisitioned through channels of the Strategic Communications Command from the Department of the Army. Men for the signal units of the field forces, divisions, and


Photograph: Cable-Splicers At Work At A Large Fixed Base


separate brigades were requisitioned through U.S. Army, Vietnam, from the Department of the Army. Of necessity, requisitions were submitted many months in advance of the arrival of the replacements, and often the requirement for an individual with a particular specialty in a specific unit had been satisfied by other means prior to his arrival in Vietnam. In order to utilize replacements most effectively and retain the flexibility necessary to respond to the changing requirements, a weekly meeting was established in 1968 between the 1st Signal Brigade and the communications-electronics staff of the U.S. Army, Vietnam, to discuss the personnel situation. Decisions were then made to divert incoming manpower resources or to reassign men already in Vietnam to meet urgent requirements. Through this procedure the possible detriment of the dual replacement stream was avoided, and an effective method emerged for using signal officers and enlisted men arriving in Vietnam.


Supply and Maintenance Support

The communications equipment used in Vietnam ranged in size and complexity from large, fixed-plant items to the squad radio used by the infantry soldier. All this equipment required an efficient repair and supply system in order to insure continuing communications. The procedures for providing this support differed between the mobile and fixed communications items and these differences ultimately led to problems.

An appreciation of the difficulties inherent in communications supply support can be gained by an examination of the sheer magnitude of the communications-electronics logistics effort at the height of the Vietnam War. An estimated one-third of all the major items of equipment in Vietnam were communications-electronics items. Over 50,000 different types of communications-electronics replacement and repair parts were stocked by the supply system in Vietnam. And there were more than 150 direct and general support supply and maintenance facilities in Vietnam that dealt with communications-electronics equipment.

The supply and maintenance support for the communications equipment of the combat units and of the corps area support battalions under the 1st Signal Brigade was standardized, following the guidelines of the Army's logistics doctrine. This support functioned as effectively as the over-all Army logistics system in Vietnam functioned. When the U.S. Forces began to arrive in strength, the huge logistical buildup created unprecedented problems which the Army had to solve in order to fight a computerized war in the counterinsurgency combat environment of Vietnam. However, in time the depot and support command system of management functioned well, and the computer as a tool of logistic management came of age in Vietnam.

The standardization that was possible for mobile communications-electronics equipment was not feasible for the fixed-plant communications equipment used in Vietnam. Our fixed signal equipment in Southeast Asia was mainly a combination of commercial equipment provided by and partly or wholly maintained by two commercial contractors. Such equipment was new to the Army and involved uncommon components that were not found at all in the field army maintenance support system. These items, therefore, presented unprecedented problems for the logistician in the matter of the availability of repair parts, the application of standard Army maintenance doctrine, and the training of military technicians to maintain the equipment.


Photograph: Calibrating Equipment At 1st Signal Brigade Can Tho Site


The problems were apparent to both the logistician and the communicator alike. During the summer of 1968 a Department of the Army team, headed by Brigadier General Hugh F. Foster, Jr., prepared a study of communications-electronics support in Southeast Asia. The study defined the logistics concepts and the support responsibilities for the fixed communications systems in Southeast Asia. Specifically, it recommended that three area maintenance and supply facilities be established, two in Vietnam and one in Thai­land. These facilities, to be operated solely by and for the 1st Signal Brigade, were to furnish the maintenance and supply support for the commercially procured, fixed-plant communications equipment in Southeast Asia.

In October 1968 approval of the recommendation came from the Department of the Army, and construction of facilities at Bangkok, Thailand, and at Long Binh, Vietnam, was begun promptly. The Thailand complex, under the 29th Signal Group, became operational in June 1969, and the Long Binh facility followed a month later. Shortly thereafter, construction was started


on the third facility at Cam Ranh Bay, which became operational in the spring of 1970.

The activation of these area maintenance and supply facilities solved one of the major problems in the support of fixed communications systems. These systems, previously supported by contracts and ill-defined maintenance and supply channels, were now supported from a single central facility in each of the three designated geographical areas of responsibility.


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