Both the forces engaged were provisional, assembled from scattered forces operating for the most part on security and antiguerrilla missions. The Federals had been gathered from numerous isolated posts over the six weeks preceding the battle. Few of the units had performed before in standard brigade and division operations. General Sigel had completed assembling his forces at Martinsburg and Winchester on 29 April. He developed his organizational structure during his slow movement south. Even more immediately, the Confederate forces were gathered as the Federal plan revealed itself. General Breckinridge began to consolidate his forces on 7 May, completing his new arrangement at Staunton on 12 May, three days before the battle.

First Infantry Division—Brig. Gen. Jeremiah C. Sullivan

    1st Brigade—Col. Augustus Moor

18th Connecticut Infantry—Maj. Henry Peale
28th Ohio Infantry—Lt. Col. Gottfried Becker
116th Ohio Infantry—Col. James Washburn
123d Ohio Infantry—Maj. Horace Kellogg

1st West Virginia Infantry—Lt. Col. Jacob Weddle
12th West Virginia Infantry—Col. William B. Curtis
34th Massachusetts Infantry—Col. George D. Wells
54th Pennsylvania Infantry—Col. Jacob M. Campbell

    1st Brigade—Col. William B. Tibbitts

1st New York Cavalry (-) (Veteran)—Col. Robert F. Taylor
1st New York Cavalry (Lincoln)—Lt. Col. Alonzo W. Adams
1st Maryland Cavalry (det.) (Potomac Home) —Maj. J. T. Daniel
21st West Virginia Cavalry—Maj. Charles C. Otis
14th Pennsylvania Cavalry—Capt. Ashbel F. Duncan

15th New York Cavalry—Maj. H. Roessler
20th Pennsylvania Cavalry—Maj. R. B. Douglas
22d Pennsylvania Cavalry (det.)—1st Lt. Caleb McNulty

Battery B, Maryland Light (3" rifle)—Capt. Alonzo Snow
30th Battery, New York (12-lb. Nap.)—Capt. Albert von Kleiser
Battery D, 1st West Virginia Light (3" rifle)—Capt. John Carlin
Battery G, 1st West Virginia Light (3" rifle)—Capt. Chatham T. Ewing
Battery B, 5th United States (3" rifle)—Capt. Henry A. DuPont

Infantry Division
 
    1st Brigade—Brig. Gen. John Echols

22d Virginia Infantry—Col. George S. Patton
23d Virginia Battalion—Lt. Col. Clarence Derrick
26th Virginia Battalion—Lt. Col. George M. Edgar

30th Virginia Battalion—Lt. Col. J. Lyle Clark
51st Virginia Infantry—Lt. Col. John P. Wolfe
62d Virginia Infantry (Mtd.)—Col. George H. Smith
Co. A, 1st Missouri Cavalry (Inf.)—Capt. Charles H. Woodson
23d Virginia Cavalry (Inf.)—Col. Robert White
VMI Cadets—Lt. Col. Scott Shipp

18th Virginia Cavalry—Col. George W. Imboden
Misc. dets. 2d Maryland, 23d Virginia, 43d Virginia (Partisans)

Chapman's (Virginia) Battery (4 how., 2 rifle)—Capt. George B. Chapman
Jackson's (Virginia) Battery (I rifle, 3 12-lb. Nap.)—1st Lt. Randolph H. Blain
McClanahan's (Virginia) Battery (2 how., 4 rifle)—Capt. John McClanahan
VMI Section (2 rifle)—Cadet Capt. C. H. Minge
 

Three-Inch Ordnance Rifle

• Fires 10-lb. projectiles (conical bolt, case, shell, canister)
• Bore diameter, 3"
• Tube weight, 820 lbs., wrought iron
• Range, 1,830 yds. at 5° elevation
• Muzzle velocity, 1215 FPS
• Use: Infantry support in open areas, counterbattery.

• Fires 12-lb. projectiles (solid, case, shell, canister)
• Bore diameter, 4.62"
• Tube weight, 1227 lbs., bronze
• Range, 1,619 yds. at 5° elevation
• Muzzle velocity, 1485 FPS
• Use: Close infantry support in wooded areas, final defense.

• Fires 10-lb. projectiles (conical bolt, case, shell, canister)
• Bore diameter, 3"
• Tube weight, 890 lbs., iron
• Range, 2,000 yds. at 5° elevation
• Muzzle velocity, 1300 FPS
• Use: Same as ordnance rifle.

Field Howitzer, 12-pounder

• Fires 12-lb. projectiles (solid, case, shell, canister)
• Bore diameter, 4.62"
• Tube weight, 788 lbs., bronze
• Range, 1,072 yds. at 5° elevation
• Muzzle velocity, 1200 FPS
• Use: High-trajectory antipersonnel.