On September 29, 1789, the final day of its 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.” The act legalized the existing U.S. Army, a small force inherited from the Continental Congress that had been created under the Articles of Confederation.

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 capital, Congress neglected dealing with the issue of military forces until prodded by President and Commander in Chief George Washington.

On August 7, Washington reminded both Houses that the provision for troops made under the Continental Congress must be superseded by action under the new Constitution. The establishment of United States troops was an issue, the president wrote:

…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. George Washington to Congress, August 7, 1789, Indian Affairs. Series 2, Letterbooks 1754-1799. Letterbook 25, April 6, 1789 – March 4, 1791. George Washington Papers. Manuscript Division

This appeal, delivered by Secretary of War Henry Knox, was not immediately acted upon. Three days later, on August 10, Washington again urged Congress to address the issue. Finally, on September 29, 1789, the House of Representatives and the Senate passed the act that officially established the army under the Constitution of the United States.