On April 4, 1864, the U.S. War Department issued General Orders, No. 144, announcing several major changes to the U.S. Army corps command structure as ordered by President Abraham Lincoln.
General Orders, No. 144
War Department, Adjutant General’s Office
Washington, April 4, 1864
Army Corps Commands.
I ..By direction of the President of the United States, the following changes and assignments are made in Army Corps commands:
Major General P. H. SHERIDAN is assigned to command the Cavalry Corps, Army of the Potomac.
The Eleventh and Twelfth Army Corps are consolidated, and will be called the Twentieth Army Corps. Major General J. HOOKER is assigned to the command.
Major General G. GRANGER is relieved from command of the Fourth Army Corps, and Major General O. O. HOWARD is assigned in his stead.
Major General SCHOFIELD is assigned to the command of the Twenty-third Army Corps.
Major General SLOCUM will report to Major General SHERMAN, commanding Division of the Mississippi, and Major General STONEMAN to Major General SCHOFIELD, commanding Department of the Ohio, for assignment.
Major General GRANGER will report by letter to the Adjutant General of the Army.
II.. Captain HORACE PORTER, U. S. Ordnance Department, is announced as an Aide-de-Camp to Lieutenant General GRANT, with the rank of Lieutenant Colonel.
BY ORDER OF THE SECRETARY OF WAR:
Assistant Adjutant General.