Este es el orden de Batalla de ambos contendientes en Bull Run o Manassas en julio de 1861.
U.S. ARMY
FIRST DIVISION (Commanded by Brigadier General DANIEL TYLER)
First Brigade (Commanded by Colonel E. D. KEYES)
1st Maine Infantry
1st Connecticut Infantry
2nd Connecticut Infantry
3rd Connecticut Infantry
Second Brigade (Commanded by Brigadier General R. C. SCHENCK)
2nd New York (State Militia) Infantry
1st Ohio Infantry
2nd Ohio Infantry
Battery E, Second U.S. Artillery
Third Brigade (Commanded by Colonel W. T. SHERMAN)
13th New York Infantry
69th New York Infantry
79th New York Infantry
2nd Wisconsin Infantry
Battery E, Third U.S. Artillery
Fourth Brigade (Commanded by Colonel I. B. RICHARDSON)
1st Massachusetts Infantry
12th New York Infantry
2nd Michigan Infantry
3rd Michigan Infantry
Battery G, First U.S. Artillery
Battery M, Second U.S. Artillery
SECOND DIVISION (Commanded by Colonel ANDREW PORTER)
First Brigade (Commanded by Colonel ANDREW PORTER)
8th New York (Militia) Infantry
14th New York Infantry
27th New York Infantry
Battalion U.S. Infantry (2nd Infantry, Co C & G - 3rd Infantry, Co B, E, G & I - 8th Infantry, Co G)
Battalion U.S. Marines
Battalion U.S. Cavalry (1st Cavalry, Co A & E - 2nd Cavalry, Co B, E, G & I - 2nd Dragoons, Co K)
Battery D, Fifth U.S. Artillery
Second Brigade (Commanded by Colonel A. E. BURNSIDE)
2nd New Hampshire Infantry
1st Rhode Island Infantry
2nd Rhode Island Infantry + 1 battery of Light Artillery
71st New York Infantry + 2 howitzers
THIRD DIVISION (Commanded by Colonel S. P. HEINTZELMAN) - wounded
First Brigade (Commanded by Colonel W. B. FRANKLIN)
5th Massachusetts Infantry
11th Massachusetts Infantry
1st Minnesota Infantry
Company I, First U.S. Artillery
Second Brigade (Commanded by Colonel O. B. WILLCOX) - wounded and captured
11th New York (Fire Zouaves) Infantry
38th New York Infantry
1st Michigan Infantry
4th Michigan Infantry (not engaged)
Battery D, Second U.S. Artillery
Third Brigade (Commanded by Colonel O. O. HOWARD)
3rd Maine Infantry
4th Maine Infantry
5th Maine Infantry
2nd Vermont Infantry
FOURTH DIVISION - RESERVE (Commanded by Brigadier General THEODORE RUNYON) Not engaged
Three Months Enlistment
1st New Jersey Infantry
2nd New Jersey Infantry
3rd New Jersey Infantry
Three years Enlistment
1st New Jersey Infantry
2nd New Jersey Infantry
4th New Jersey Infantry
41st New York Infantry
FIFTH DIVISION (Commanded by Colonel DIXON S. MILES)
First Brigade (Commanded by Colonel LOUIS BLENKER)
In reserve at Centreville and not engaged in main battle. Involved in minor skirmishes with Confederate troops while covering the retreat of the Army
8th New York Infantry (Volunteers)
29th New York Infantry
39th New York Infantry
27th Pennsylvania Infantry
Battery A, Second U.S. Artillery
Bookwood's New York Battery (Consisted of the field guns of the 8th New York Militia, manned by detachments from the 8th and 29th Regiments New York Volunteer Infantry)
Second Brigade (Commanded by Colonel THOMAS A. DAVIES)
16th New York Infantry
18th New York Infantry
31st New York Infantry
32nd New York Infantry
Battery G, Second U.S. Artillery
C.S. ARMY
ARMY OF THE POTOMAC (Commanded by Brigadier General P. G. T. BEAUREGARD)
First Brigade (Commanded by Brigadier General MILLEDGE L. BONHAM)
11th North Carolina Infantry
2nd South Carolina Infantry
3rd South Carolina Infantry
7th South Carolina Infantry
8th South Carolina Infantry
8th Louisiana Infantry
30th Virginia Cavalry
Radford Rangers
Botetourt Dragoons
Hanover Light Dragoons
Fairfax Cavalry
Lieutenant Colonel W. Munford's Squadron
Black Horse Troop
Chesterfield Light Dragoons
Franklin Rangers
Alexandria Light Artillery
1st Company, Richmond Homitzers
Second Brigade (Commanded by Brigadier General RICHARD S. EWELL)
5th Alabama Infantry
6th Alabama Infantry
6th Louisiana Infantry
Lieutenant Colonel W. H. Jenifer's Cavalry Battalion
1st Company, Washington Artillery
Third Brigade (Commanded by Brigadier General D. R. JONES)
17th Mississippi Infantry
18th Mississippi Infantry
5th South Carolina Infantry
Appomattox Rangers, 30th Virginia Cavalry
2nd Company, Washington Artillery
Fourth Brigade (Commanded by Brigadier General JAMES LONGSTREET)
5th North Carolina Infantry
1st Virginia Infantry
11th Virginia Infantry
17th Virginia Infantry
24th Virginia Infantry
Amherst Mounted Rangers, 30th Virginia Cavalry
3rd Company, Washington Artillery
Fifth Brigade (Commanded by Colonel P. ST. GEORGE COCKE)
8th Virginia Infantry
18th Virginia Infantry
19th Virginia Infantry
28th Virginia Infantry
49th Virginia Battalion
Wise Troop
Loudoun Artillery
Lynchburg Artillery
Sixth Brigade (Commanded by Colonel JUBAL A. EARLY)
7th Louisiana Infantry
13th Mississippi Infantry
7th Virginia Infantry
4th Company, Washington Artillery
Seventh Brigade (Commanded by Colonel NATHAN G. EVANS)
4th South Carolina Infantry
1st Special Louisiana Battalion
Campbell Rangers, 30th Virginia Cavalry
Clay Dragoons, 30th Virginia Cavalry
Reserve Brigade (Commanded by Brigadier General THEOPHILUS H. HOLMES)
1st Arkansas Infantry
2nd Tennessee Infantry
Hampton's South Carolina Legion (6 companies)
Purcell Artillery
Camp Picken's Battery
ARMY OF THE SHENANDOAH (Commanded by General JOSEPH E. JOHNSTON)
First Brigade (Commanded by Brigadier General THOMAS J. JACKSON)
2nd Virginia Infantry
4th Virginia Infantry
5th Virginia Infantry
27th Virginia Infantry
33rd Virginia Infantry (8 companies)
Rockbridge Artillery
Second Brigade (Commanded by Colonel FRANCIS BARLOW)
7th Georgia Infantry
8th Georgia Infantry
Wise Artillery
Third Brigade (Commanded by Brigadier General BARNARD E. BEE)
4th Alabama Infantry
2nd Mississippi Infantry
11th Mississippi Infantry (Companies A and F)
6th North Carolina Infantry
Staunton Artillery
Fourth Brigade (Commanded by Brigadier General EDMUND KIRBY SMITH)
1st Maryland Battalion Infantry
3rd Tennessee Infantry
10th Virginia Infantry
Culpeper Artillery
Not Brigaded
1st Virginia Cavalry
Thomas Artillery
Fuentes: The Official Records of the Union and Confederate Armies y The Civil War Archive
Saludos