No. The Department of Defense was created as the National Military Establishment by the National Security Act of 1947. It was renamed the Department of Defense in an amendment to that law that was passed in 1949. Since that time, any change to the Department of Defense—such as the Defense Reorganization Act of 1958 or the Goldwater-Nichols Act of 1986—has required an act of Congress. Trump’s executive order created the Department of War as a “secondary title” for the Department of Defense.