History of the United States Army

History of the United States Army began with its founding on 14 June 1775 by the Second Continental Congress to fight the American Revolutionary War. It evolved from the Continental Army, commanded by George Washington, into a permanent federal force established by the United States Congress in 1784. Over more than two centuries, it has grown from a small militia-based force into the world's premier land power, playing a decisive role in securing American independence, expanding the nation's territory, preserving the Union, and defending U.S. interests globally through major conflicts and peacetime engagements.

Origins and the Revolutionary War (1775–1783)

The army's genesis was the Continental Army, created after the opening battles at Lexington and Concord. The Second Continental Congress appointed George Washington as its commander-in-chief, facing the formidable British Army and Hessian mercenaries. Key early engagements included the Siege of Boston, the Battle of Long Island, and the pivotal Battle of Saratoga, which convinced France to ally with the United States. Enduring the harsh winter at Valley Forge, the army was professionalized by Friedrich Wilhelm von Steuben and ultimately, with crucial French naval support at the Siege of Yorktown, secured American independence under the Treaty of Paris (1783). The army was largely disbanded after the war, leading to the Pennsylvania Mutiny of 1783 and highlighting the need for a standing military.

19th century: Expansion, Civil War, and Indian Wars

The early national army, authorized by the Militia Acts of 1792, fought in the Northwest Indian War and the War of 1812, which included the burning of Washington, D.C. but victories at the Battle of New Orleans and Battle of Lake Erie. Under commanders like Winfield Scott, it drove expansion through the Mexican–American War, capturing Mexico City. The American Civil War became its bloodiest conflict, pitting the Union Army against the Confederate States Army in epic battles like Gettysburg and Antietam. Following the war, the United States Cavalry and Infantry were engaged in decades of American Indian Wars across the Great Plains, culminating in the Wounded Knee Massacre. The century closed with the Spanish–American War and the Philippine–American War.

World Wars and the rise of a global power (1917–1945)

The American Expeditionary Forces, led by General John J. Pershing, entered World War I on the Western Front, fighting in major offensives like the Meuse–Argonne offensive. The interwar period saw stagnation, but World War II triggered unprecedented expansion under Chiefs of Staff George C. Marshall and Douglas MacArthur. The army fought in both the European and Pacific Theaters, executing massive operations like the Normandy landings, the Battle of the Bulge, and the island hopping campaign. The Manhattan Project, an army-managed endeavor, developed the atomic bombings of Hiroshima and Nagasaki, ending the war and positioning the United States as a superpower.

Cold War and late 20th century conflicts

The Cold War saw the army as the bulwark of NATO in Europe, facing the Soviet Union and Warsaw Pact. It fought major conventional wars in Korea, under United Nations Command, and Vietnam, a protracted counterinsurgency marked by battles like the Battle of Ia Drang and the Tet Offensive. The post-Vietnam era brought the All-Volunteer Force and a focus on AirLand Battle doctrine. The army led the Gulf War coalition to victory in Operation Desert Storm, showcasing advanced technology. It also conducted peacekeeping missions in Bosnia and Kosovo.

21st century: War on Terror and modernization

Following the September 11 attacks, the army invaded Afghanistan in Operation Enduring Freedom and Iraq in Operation Iraqi Freedom, engaging in prolonged counterinsurgency and stability operations. Key battles included the Battle of Fallujah and the surge in Afghanistan. The era emphasized improvised explosive device defense, MRAP vehicles, and counterterrorism partnerships. Current modernization efforts, under concepts like Multi-Domain Operations, focus on near-peer competition with China and Russia, developing new systems like the Next Generation Combat Vehicle and investing in long-range precision fires, while continuing global deployments and advising missions.

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