U.S. Army - Army of the Potomac - First Army Corps

Third Division

Brigadier General G. Meade (except 9/17-9/29)
Brigadier General T. Seymour (9/17-9/29)

Transferred from Army of Virginia - 3rd Army Corps on September 12, 1862

First Brigade

Brigadier General T. Seymour (except 9/12 - 9/17)
Colonel R. Biddle Roberts (9/17-9/29)

1st Pensylvania Reserves Regiment

Col. R. Biddle Roberts (except 9/12 - 9/17)

Captain William C. Talley (9/17-9/29)

from Army of Virginia,
3rd Corps, 3rd Division, 1st Brigade

2nd Pensylvania Reserves Regiment

Captain James N. Byrnes

5th Pensylvania Reserves Regiment

Colonel Joseph W. Fisher

6th Pensylvania Reserves Regiment

Colonel William Sinclair

13th Pensylvania Reserves Regiment

Colonel Hugh McNeil (mw 9/16)

Adjutant William Hartshorne (after 9/16)

Second Brigade

Colonel Albert L. Magilton

3rd Pensylvania Reserves Regiment

Colonel Horatio Sickel (sick leave 9/1)

Lt. Colonel John C. Clark (after 9/1)

from Army of Virginia,
3rd Corps, 3rd Division, 2nd Brigade

4th Pensylvania Reserves Regiment

Major John Nyce

7th Pensylvania Reserves Regiment

Colonel Henry M. Bollinger (w 9/14)

Major Chauncey A. Lyman (after 9/14)

8th Pensylvania Reserves Regiment

Major Silas M. Baily

Third Brigade

Colonel Thomas F. Gallagher (w 9/14)

Lieutenant Colonel R. Anderson (9/14)

9th Pensylvania Reserves Regiment

Lieutenant Colonel R. Anderson (to 9/14)

Captain Samuel B. Dick (after 9/14)

from Army of Virginia,
3rd Corps, 3rd Division, 3rd Brigade

10th Pensylvania Reserves Regiment

Lt. Colonel Adoniram J. Warner (w 9/17)

Captain Jonathan P. Smith (after 9/17)

11th Pensylvania Reserves Regiment

Lt. Colonel Samuel M. Jackson

12th Pensylvania Reserves Regiment

Captain Richard Gustin

Artillery

Battery A, 1st Pennsylvania Artillery

Lieutenant John G. Simpson

from Army of Virginia,
3rd Corps, 3rd Division, Artillery

Battery B, 1st Pennsylvania Artillery

Captain James H. Cooper

Battery G, 1st Pennsylvania Artillery

Lt. Frank P. Amsden

Battery C, 5th United States Artillery

Captain Dunbar R. Ransom

Lieutenant Henry S. Gansevoort (temp 9/17)