The Battle of Kilrush was a battle at the start of the Eleven years war in Ireland, soon after the Irish Rebellion of 1641.It was fought in April 1642 between a Royalist army under the Earl of Ormonde, and Richard Butler, 3rd Viscount Mountgarret, who led Confederate Irish troops raised during the Irish Rebellion of 1641. Ormonde and Mountgarret were cousins, both being members of the Butler dynasty.