When the Irish Rebellion of 1641 started, Ormonde was in command of government troops based in Dublin. Most of the country was taken by the Catholic rebels, who included Ormonde's Butler relatives. Rebel leader Richard Butler, 3rd Viscount Mountgarret, was Ormonde's cousin. In spring 1642 Mountgarret and Ormonde were the commanders of the two sides at the battle of Kilrush, with Ormonde's side winning.