The United States Congress Passes An Act Officially Creating The Military Of The United States
On September 29, 1789, the final day of its very first session, the United States Congress passed "An act to recognize and adapt to the Constitution of the United States, the establishment of the troops raised under the resolves of the United States in Congress assembled" officially creating the military of the United States. To the men already serving on the frontier under orders of the Continental Congress, the change probably meant little.
Although the Constitution of the United States charged Congress with raising and regulating military forces, newly-elected House and Senate members delayed acting on this provision. Busy organizing the federal government and debating the location of the new Federal City, Congress neglected dealing with the issue of military forces until prodded by President and Commander in Chief George Washington.
The United States Department of War, also called the War Office, was the cabinet department originally responsible for the operation and maintenance of the US Army. It was also responsible for naval affairs until the establishment of the Navy Department in 1798, and for land-based air forces until the creation of the Department of the Air Force in 1947.
The War Department existed from 1789 until September 18, 1947, when it was renamed as the Department of the Army, and became part of the new, joint National Military Establishment (NME). Shortly after, in 1949, the NME was renamed to the Department of Defense, which the Dept of the Army is part of today.
the national importance and necessity of which I am deeply impressed; I mean some uniform and effective system for the Militia of the United States. It is unnecessary to offer arguments in recommendation of a measure, on which the honor, safety and well being of our Country so evidently and essentially depend: But it may not be amiss to observe that I am particularly anxious it should receive an early attention as circumstances will admit; because it is now in our power to avail ourselves of the military knowledge disseminated throughout the several States by means of the many well instructed Officers and soldiers of the late Army; a resource which is daily diminishing by deaths and other causes.”— Letter from George Washington to Congress, August 7, 1789. George Washington Papers