Oliver Cromwell (1599–1658) was an English military and political leader best known for making England a republic and leading the Commonwealth of England.

In Irish history he is represented as a brutal conqueror.  The Cromwellian conquest of Ireland (1649-53) refers to the re-conquest of Ireland by the forces of the English Parliament, led by Cromwell.

Since the Irish Rebellion of 1641, Ireland had been mainly under the control of the Irish catholics.

Cromwell invaded in 1949 and his forces defeated this group.  He then passed a very harsh series of Penal laws against Roman Catholics and confiscated almost all of their land.  He gave this land to English and Scottish people who moved to Ireland to use it.