U.S. Army - Army of the Potomac

Fourth Army Corps

Brigadier General Erasmus D. Keyes

Created March 3, 1862 by order of Preseident Lincoln in Genral Order Number 101

First Division

Brigadier General Darius N. Couch

1st Brigade

Colonel H. S. Briggs

2nd Brigade

Brigadier General L. P. Graham

3rd Brigade

Brigadier General J. J. Peck

Second Division

Brigadier General William F. Smith

1st Brigade

Brigadier General Winfield S. Hancock

2nd Brigade

Brigadier General W. T. H. Brooks

3rd Brigade

Brigadier General J. W. Davidson

Third Division

Brigadier General Silas Casey

1st Brigade

Brigadier General H. M. Naglee

2nd Brigade

Brigadier General William H. Keim

3rd Brigade

Brigadier General I. N. Palmer