Along with Lawrence Crawford, this man was a leader of the Eastern Associat
Along with Lawrence Crawford, this man was a leader of the Eastern Association, and he championed the "four fundamentals." Henry Ireton served under this man during a campaign that was preceded by the Battle of Rathmines and saw massacres following the sieges of Drogheda and Wexford. This former subordinate of Thomas Fairfax took power following Pride's Purge and won the battles of Naseby and Marston Moor. A member of the "Roundheads,"  he was nicknamed "Old Ironsides" and commanded the New Model Army. For 10 points, identify this man who after the death of Charles I became the Lord Protector of the Commonwealth of England.
Along with Lawrence Crawford, this man was a leader of the Eastern Association, and he championed the "four fundamentals."
Oliver Cromwell