Department of Washington, was a department of the Union Army constituted on April 9, 1861. It consisted of the District of Columbia to its original boundaries, and the State of Maryland as far as Bladensburg. It was merged into the Military Division of the Potomac on July 25, 1861. Later it was recreated on February 2, 1863 as the consolidated Department of Washington and XXII Corps. It was again made the Department of Washington in 1865 and that command remained until 1869 when it was disbanded.