The Pancho Villa Expedition—now known officially in the United States as the Mexican Expedition, but originally referred to as the "Punitive Expedition, U.S. Army"—was a military operation conducted by the United States Army against the paramilitary forces of Mexican revolutionary Francisco "Pancho" Villa from March 14, 1916, to February 7, 1917, during the Mexican Revolution of 1910–1920.

The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution. The Army is the oldest branch of the U.S. military and the most senior in order of precedence. It has its roots in the Continental Army, which was formed on 14 June 1775 to fight against the British for independence during the American Revolutionary War (1775–1783). After the Revolutionary War, the Congress of the Confederation created the United States Army on 3 June 1784 to replace the disbanded Continental Army. The United States Army considers itself a continuation of the Continental Army, and thus considers its institutional inception to be the origin of that armed force in 1775.