The Third Battle of Winchester, also known as the Battle of Opequon or Battle of Opequon Creek, was an American Civil War battle fought near Winchester, Virginia, on September 19, 1864. Union Army Major General Philip Sheridan defeated Confederate Army Lieutenant General Jubal Early in one of the largest, bloodiest, and most important battles in the Shenandoah Valley. Among the 5,000 Union casualties were one general killed and three wounded. The casualty rate for the Confederates was high: about 4,000 of 15,500. Two Confederate generals were killed and four were wounded. Participants in the battle included two future presidents of the United States, two future governors of Virginia, a former vice president of the United States, and a colonel whose grandson, George S. Patton became a famous general in World War II.

The city of Winchester, Virginia, and the surrounding area, were the site of numerous battles during the American Civil War, as contending armies strove to control the lower Shenandoah Valley. Winchester changed hands more often than any other Confederate city.