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Commanded by Major General Samuel P. Heintzelman
Defences North of the Potomac Lieutenant Colonel Joseph A. Haskin  
First Brigade Colonel A. A. Gibson (to 3/26)
Colonel J. M. Warner
3rd  Maine Battery/
1st Maine Heavy Artillery, Co. M
  redesignated as heavy artillery
2nd Pennsylvania Heavy Artillery Colonel Augustus A. Gibson  
1st Vermont Heavy Artillery Colonel James M. Warner  
Second Brigade Colonel Lewis O. Morris  
16th Indiana Battery    
1st Maine Heavy Artillery Colonel Daniel Chaplin  
7th New York Heavy Artillery Colonel Lewis O. Morris  
9th New York Heavy Artillery Colonel Joseph Welling  
9th New York Independent Battery    
117th New York Infantry, 2nd Battalion    
Third Brigade Colonel William R. Pease   
5th New York Heavy Artillery,
Companies A, I, K, L & M
10th New York Heavy Artillery    
117th New York Infantry, 1st Battalion    
Abercrombie’s Division Brigadier General J. J. Abercrombie  
Provisional Brigade Colonel Clarence Buell  
152nd New York Infantry Regiment Colonel Alonzo Ferguson  
153rd New York Infantry Regiment Major Edwin P. Davis (to Col. 3/21)  
169th New York Infantry Regiment Lieutenant Colonel John McConihe  
Second Brigade Colonel B. Porter  
22nd Connecticut Infantry Regiment    
40th Massachusetts Infantry Regiment    
141st New York Infantry Regiment    
16th West Virginia Infantry Regiment    
Third Brigade Colonel William Gurney  
127th New York Infantry Regiment    
142nd New York Infantry Regiment    
143rd New York Infantry Regiment    
144th New York Infantry Regiment    
9th Massachusetts Battery Captain John Bigelow  
17th New York Independent Battery    
4th New York Heavy Artillery    
Casey’s Division Major General Silas Casey  
First Brigade Colonel Francis Fessenden   
25th Maine Infantry Regiment    
27th Maine Infantry Regiment    
Second Brigade Brigadier General Edwin H. Stoughton (c 3/8)
Brigadier General George J. Stannard (3/11)
12th Vermont Infantry Regiment    
13th Vermont Infantry Regiment    
14th Vermont Infantry Regiment    
15th Vermont Infantry Regiment    
16th Vermont Infantry Regiment    
Third Brigade Brigadier General Alexander Hays  
39th New York Infantry Regiment    
111th New York Infantry Regiment    
125th New York Infantry Regiment    
126th New York Infantry Regiment    
9th Massachusetts Battery    
17th New York Independent Battery    
2nd Connecticut Independent Battery    
11th Massachusets Independent Battery    
4th New York Heavy Artillery    
1st Rhode Island Light Artillery, Battery H    
Keystone (Pennsylvania) Battery    
Pennsylvania Reserves Division Colonel Horatio G. Sickel  
First Brigade Colonel William McCandless (to 3/29)
Colonel William Sinclair
1st Pennsylvania Reserves Regiment    
2nd Pennsylvania Reserves Regiment    
6th Pennsylvania Reserves Regiment    
13th Pennsylvania Reserves Regiment    
Second Brigade Colonel H. C. Bollinger  
3rd Pennsylvania Reserves Regiment    
4th Pennsylvania Reserves Regiment    
7th Pennsylvania Reserves Regiment    
8th Pennsylvania Reserves Regiment    
Third Brigade Colonel J. W. Fisher  
5th Pennsylvania Reserves Regiment    
9th Pennsylvania Reserves Regiment    
10th Pennsylvania Reserves Regiment    
11th Pennsylvania Reserves Regiment    
12th Pennsylvania Reserves Regiment    
Jewett’s Independent Brigade Colonel A. B. Jewett  
23rd Maine Infantry Regiment Colonel William W. Virgin  
39th Massachusetts Infantry Regiment Colonel P. Stearns Davis  
14th New Hampshire Infantry Regiment Colonel Robert Wilson  
10th Vermont Infantry Regiment Colonel Albert B. Jewett  
11th New York Cavalry, Cos. E, F & I    
10th Massachusetts Independent Battery    
Independent Cavalry Brigade Colonel R. Butler Price to Cav. Div. 3/21 (below)
1st Michigan Cavalry Regiment   to 2nd Brig. 
5th New York Cavalry Regiment   to 3rd Brig.
1st Ohio Cavalry Regiment, Cos. A & C   to 2nd Brig.
2nd Pennsylvania Cavalry Regiment   to 2nd Brig.
18th Pennsylvania Cavalry Regiment   to 3rd Brig.
1st Vermont Cavalry Regiment   to 2nd Brig.
1st West Virginia Cavalry Regiment   to 3rd Brig.
Cavalry Division Major General Julius H. Stahel created 3/21
Cavalry Division Brigadier General Joseph T. Copeland created 3/21
5th Michigan Cavalry Regiment    
6th Michigan Cavalry Regiment    
7th Michigan Cavalry Regiment    
Second Brigade Colonel R. Butler Price  
1st Michigan Cavalry Regiment    
1st Ohio Cavalry Cos. A&C    
2nd Pennsylvania Cavalry Regiment    
1st Vermont Cavalry Regiment    
Third Brigade Colonel O. DeForest  
5th New York Cavalry Regiment    
18th Pennsylvania Cavalry Regiment    
1st West Virginia Cavalry Regiment    
District of Washington Brigadier General John H. Martindale  
2nd District of Columbia Infantry Regiment Colonel Charles M. Alexander  
10th New Jersey Infantry Regiment Colonel William R. Murphy  
118th New York Infantry Regiment    
27th Pennsylvania Infantry, Co. F    
150th Pennsylvania Infantry, Co. K    
157th Pennsylvania Infantry (4 cos.)    
District of Alexandria Brigadier General John P. Slough  
1st District of Columbia Infantry Regtiment    
26th Michigan Infantry Regiment    
153rd New York Infantry Regiment Major Edwin P. Davis (to Col. 3/21)  
11th Rhode Island Infantry Regiment Colonel George E. Church  
Artillery, Distict of Alexandria Brigadier General Robert O. Tyler  
1st Connecticut Heavy Artillery Colonel Henry L. Abbott  
19th Connecticut Infantry (Hv. Artillery) Colonel Leverette Wessells  
Artillery Brigade South of the Potomac Colonel M. Cogswell  
1st Massachusetts Heavy Artillery    
34th Massachusetts Infantry Regiment Colonel George D. Wells  
2nd New York Heavy Artillery    
3rd New York Heavy Artillery Battalion    
1st Wisconsin Heavy Artillery    
Camp Barry, Light Artillery Camp  Brigadier General William F. Barry  
1st Delaware Battery    
9th Michigan Battery   to Cav. Div. (above)
10th Michigan Battery   from Michigan
1st New York Artillery, Battery A    
12th New York Independent Battery    
16th New York Independent Battery    
19th New York Independent Battery    
27th New York Independent Battery    
1st West Virginia Artillery, Battery A    
Pennsylvania Independent Battery H