United States Secretary of War

The Secretary of War was a member of the United States President's Cabinet, beginning with George Washington's administration. A similar position, called either "Secretary at War" or "Secretary of War," was appointed to serve the Congress of the Confederation under the Articles of Confederation between 1781 and 1789. Benjamin Lincoln and later Henry Knox held the position. When Washington was inaugurated as the first president under the Constitution, he appointed Knox to continue serving. 
The Secretary of War led the War Department. At first, he was responsible for all military affairs. In 1798, the Secretary of the Navy was added to the cabinet, and the scope of this office was reduced to a general concern with the Army. In 1947, the departments were recombined under the Secretary of Defense. The Secretary of War was replaced by the Secretary of the Army and the Secretary of the Air Force, non-Cabinet positions under the Secretary of Defense.