United States Department of War Law and Legal Definition

The United States Department of War, also called the War Department was the United States Cabinet department originally responsible for the operation and maintenance of the United States military. The Secretary of War headed the war department throughout its existence.

The Secretary of War was a civilian with such responsibilities as finance and purchases and a minor role in directing military affairs, headed the War Department. Shortly after the establishment of government under the current Constitution of the United States of America, President George Washington and Congress created the War Department as a civilian agency to administer the field army under the president (as commander in chief) and the secretary of war.

The War Department existed from 1789 until September 18, 1947.when it split into Department of the Army and Department of the Air Force and joined the Department of the Navy as part of the new joint National Military Establishment (NME), renamed the United States Department of Defense in 1949.