Confederate Ireland, also referred to as the Irish Catholic Confederation, was a period of Irish Catholic self-government between 1642 and 1652, during the Eleven Years' War. Formed by Catholic aristocrats, landed gentry, clergy and military leaders after the Irish Rebellion of 1641, the Confederates controlled up to two-thirds of Ireland from their base in Kilkenny; hence it is sometimes called the Confederation of Kilkenny.