War, Department of, also called the War Department, was an executive department of the United States government from 1789 to 1947. This department was set up to supervise all military activities and all phases of national defense. In 1798, Congress separated the naval forces from the land forces, creating a new Department of the Navy. The Department of War retained control over the Army. The secretaries of both departments reported to the president, were members of the president's Cabinet, and cooperated through joint committees and conferences.