Horatio Gates brought experience in the British Army to the American Revolutionary cause. Appointed the Continental Army's adjutant general in 1775, he helped organize records, recruiting and orders during the siege of Boston. This work helped transform provincial forces into an army. Promoted to major general in 1776, he held northern commands before replacing Philip Schuyler as commander of the Northern Department in August 1777.

Gates directed the American army against John Burgoyne's invasion from Canada. Defensive positions near the Hudson, growing American strength and aggressive fighting by subordinate commanders, notably Benedict Arnold, checked the British advance. Gates received Burgoyne's surrender in October after the battles of Saratoga. The victory elevated his reputation and contributed to the conditions for the French alliance, although it resulted from a wider campaign rather than his actions alone.

Congress then made him president of a reorganized Board of War. Its authority and proposals brought it into conflict with Washington's command. Rivalries surrounding the board became associated with the so-called Conway Cabal; a formal, unified plot to replace Washington should not be assumed. Gates subsequently commanded in several departments before receiving the southern command in 1780.

At Camden that August his army suffered a major defeat against Cornwallis. Poor supply, an ill-judged advance and the collapse of much of his force damaged his standing, and Nathanael Greene replaced him. Gates returned to the main army in 1782 and became involved with officers pressing Congress over unpaid compensation at Newburgh, where Washington resisted threats to civilian authority. He left military service in 1783. In New York, he later served briefly as a legislator. The contrast between Saratoga and Camden defined his reputation, but his career also encompassed organizational work and questions about the relationship between Congress and its generals.