On September 28, 1864, the U.S. War Department issued General Orders, No. 263, announcing that Joseph Hooker was replacing Samuel P. Heintzelman as commander of the Northern Department.
General Orders, No. 263
War Department, Adjutant General’s Office
Washington, September 28, 1864
I.. By direction of the President of the United States, Major General JOSEPH HOOKER is assigned to the command of the Northern Department. He will immediately proceed to Columbus, Ohio, and relieve Major General HEINTZELMAN.
II.. Major General HEINTZELMAN, on being relieved in command of the Northern Department, will repair to Wheeling, West Virginia, report thence by letter to the Adjutant General of the Army, and there wait until he receives orders.
BY ORDER OF THE SECRETARY OF WAR:
Assistant Adjutant General.