In the reorganization after the battle of Groveton and the retreat of Pope's army to Washington, the army was composed of six corps, as described p. 175. Many of the troops which had fought on the Peninsula were left at Alexandria, and other troops—Burnside's, from North Carolina; Sherman's, from Port Royal; Cox's from Western Virginia; new troops which had been but a few days in the service, and regiments from Wadsworth's command at Washington—were put in to fill their places.

It has not been possible to obtain a complete and correct list of all the regiments engaged in that battle. Some regiments, after the battle of South Mountain, were detached from their brigades, and sent on special service; others were kept in the rear, to guard the trains; others were sent on flank movements. But much care has been taken in the description of that battle to give the exact position of the divisions engaged, and also the brigades, so that it will be comparatively easy to ascertain the general position of most of the regiments.

ORGANIZATION OF THE ARMY OF THE POTOMAC, APRIL, 1862.

CAVALRY RESERVE. BRIG.-GEN. P. ST. G. COOK.

Emory's Brigade. 5th U. S. Cavalry.
6th " "
6th Penn. "
Blake's Brigade. 1st U. S. Cavalry.
8th Penn. "
Barker's Squadron, Ill. Cavalry.

ARTILLERY RESERVE. COL. HENRY J. HUNT.

Graham'sBattery"K" & "G"1stU. S.6 Napoleonguns.
Randall's""E"1st"6 ""
Carlisle'sBattery"E"2dU. S.6 20-pds. Parrottguns.
Robertson's" 2d"6 3-in. ordnance"
Benson's""M"2d"6 " ""
Tidball's""A"2d"6 " ""
Edwards's""L" & "M"3d"6 10-pds. Parrott"
Gibson's""C" & "G"3d"6 3-in. ordnance"
Livingston's""F" & "K"3d"4 10-pds. Parrott"
Howe's""G"4th"6 Napoleon"
De Russy's""K"4th"6 ""
Weed's""I"5th"6 3-in. ordnance"
Smead's""K"5th"4 Napoleon"
Ames's""A"5th"4{

4 10-pds. Parr.

2 Napoleon

}"
Diederick's""A" N. Y.Art.Batt'n6 20-pds. Parrott"
Voegelie's""B" " ""4 " ""
Knieriem's""C" " ""4 " ""
Grimm's""D" " ""6 32-pds. Howitzers.
100guns.

VOLUNTEER ENGINEER TROOPS. GEN. WOODBURY.

15th New York Volunteers.
50th " " "