United States Army

The United States Army traces its founding to the Continental Army's establishment by the Second Continental Congress on June 14, 1775, and, following independence, was reorganized as the standing land force of the United States, becoming the nation's primary ground combat service responsible for prosecuting land warfare, occupation and stabilization operations across every major American conflict from the War of 1812 through the Civil War, both World Wars, Korea, Vietnam and the twenty-first century's wars in Iraq and Afghanistan. Structured around divisions, brigades and, more recently, more flexible brigade combat teams, the Army has evolved from a small frontier constabulary force in its early republic years into the largest branch of the U.S. armed forces by personnel, encompassing armor, infantry, artillery, aviation and extensive logistics and support functions. The Army's doctrine and organization were transformed repeatedly across its history, notably by the citizen-soldier mass mobilizations of the two World Wars and by the shift to an all-volunteer force following the end of conscription in 1973. As of the twenty-first century the Army remains the U.S. military's principal instrument for sustained ground operations, working alongside the Navy, Air Force, Marine Corps and Space Force under the Department of Defense.