Born in Essex, England, Gates became a professional soldier in the British army. He served during the French and Indian War, including Braddock's campaign to Fort Duquesne, and the Monckton expedition against French Martinique. In 1772, he purchased an estate in western Virginia. Three years later, Gates joined General Washington's staff. He provided the Continental Army's first disciplinary code, supply procedures, and camp sanitation regulations. In 1777, Gates triumphed over the British at Saratoga, earning a congressional gold medal and a public day of thanksgiving. Later, despite strained relations with Washington over an alleged coup in Gates's favor, Congress elected him president of the War Board. In 1780, as commander of the army's southern campaign, Gates misjudged the South Carolina terrain and his troops' level of readiness. He abandoned the battlefield to Cornwallis near Camden.
After the Revolution, Gates served as vice president of the national Order of the Cincinnati (the organization of former Continental Army officers) and president of its Virginia chapter. In 1790, he moved to New York, and later served in the state legislature.