George Washington's chief military opponent during the American Revolution was General Charles Cornwallis. Cornwallis served as a senior British commander and was involved in several key battles, including the Siege of Yorktown, where he ultimately surrendered to Washington's forces in 1781. This defeat marked a critical turning point in the war, significantly weakening British resolve and paving the way for American independence. Washington's strategic leadership and Cornwallis's military decisions played essential roles in shaping the outcome of the Revolution, showcasing the dynamic and often contentious nature of their military interactions.