The Siege of Drogheda took place on 3–11 September 1649 at the outset of the Cromwellian conquest of Ireland. The town of Drogheda in eastern Ireland was held by the Irish Catholic Confederation and English Royalists when it was besieged and stormed by English Parliamentarian forces under Oliver Cromwell. In the aftermath of the assault, much of the garrison and an unknown but "significant number" of civilians were killed by the Parliamentarian troops.