The Battle of Aughrim was the decisive battle of the Williamite war in Ireland. It was fought between the Jacobites and the forces of William III on 12 July 1691, near the village of Aughrim in County Galway.

At first, the Jacobite army led by the French nobleman, the Marquis de Saint-Ruth, seemed to have the advantage. The Williamite forces under the Dutch general Ginkel were drawn into a bog, and a battery of Williamite guns were spiked by the Jacobites. By chance, a cannonball fired at long range decapitated Saint-Ruth. His death demoralized the Jacobite forces, and they were routed.

The battle was the bloodiest ever fought on Irish soil – over 7,000 people were killed. It meant the effective end of Jacobitism in Ireland, although the city of Limerick held out until the autumn of 1691.