Cromwell, Oliver

English general and politician, Puritan leader of the Parliamentary side in the English Civil War. He raised cavalry forces (later called ‘Ironsides’), which aided the victory at Marston Moor in 1644, and organized the New Model Army, which he led (with General Fairfax) to victory at Naseby in 1645. He declared Britain a republic (the Commonwealth) in 1649, following the execution of Charles I. As Lord Protector (ruler) from 1653, Cromwell established religious toleration and raised Britain's prestige in Europe on the basis of an alliance with France against Spain.