Ireton's regiment was chosen by lot to accompany Cromwell in his Irish campaign. Ireton arrived in Dublin two days after Cromwell on 17 August 1649, with 77 ships full of troops and supplies. Ireton was appointed major-general and after the conquest of the south of Ireland, Lord President of Munster. He went over with John Cook with a brief to reform the law of Ireland, to anglicise it, and to make it a model for a new settlement of English law.