The United States Army traces its origin to the founding of the Continental Army on June 14, 1775, when the Continental Congress authorized a one-year enlistment of riflemen from Pennsylvania, Maryland, and Virginia to join the New England militia army besieging Boston. Late in 1776, Congress called for the Continental Army to serve for the duration of the war. The army was to consist of 88 battalions raised and equipped by the states, with officers appointed by the states. Appointment of officers actually continued to be a collaboration between Congress, the Commander in Chief, George Washington, and the states. The number of battalions was to be apportioned to the states according to their populations. While the initial number of battalions approached the authorized strength, by 1 January 1787 the Continental infantry was only able to maintain enough regiments for fifty battalions. During the Revolutionary War, battalions and regiments were essentially the same. By October 19, 1781 when the British army under General Cornwallis surrendered to the American and French forces at Yorktown, the Continental Army had grown to sixty battalions.