The Rebellion broke out in Ulster on the night of 22/3 October, led by Rory O'More and Sir Phelim O'Neill, members of a Gaelic aristocracy increasingly apprehensive about their property rights. On one side was an unstable alliance of the Old English and the Old Irish known as the Confederation of Kilkenny; on the other was a combination of Irish Royalists and Parliamentarians. In 1642 Eoghan Ruadh Ó Néill returned from service in the Spanish army to lead the Confederation forces. A year-long truce struck with James Butler, Earl of Ormond, foundered after the Battle of Benburb, when Ó Néill routed an English army in Co. Tyrone in 1646. In spring of 1649 Cromwell arrived with his New Model Army. Within six months the Confederation had collapsed, and after the notorious massacres at Drogheda and Wexford many Irish towns capitulated. In the English Parliament, an Act of Settlement (1652) and an Act of Satisfaction (1653) were passed legitimizing the confiscation of all property in Catholic hands east of the Shannon. A virulent propaganda literature describing alleged atrocities committed by the Catholic insurgents against Protestant planters flourished in the years after the outbreak of the Rebellion.




