Oliver Cromwell (April 25, 1599 – September 3, 1658) was an English military leader and politician. After leading the overthrow of the British monarchy he ruled England, Scotland and Ireland as Lord Protector from December 16, 1653 until his death, which is believed to have been due either to malaria or poisoning.
At the outset of the English Civil War, Cromwell began his military career by raising a cavalry troop which became the basis of his Ironsides Cavalry. Cromwell's leadership in the Battle of Marston Moor in (1644) brought him to great prominence. As a leader of the Parliamentarian cause, and commander of the New Model Army (informally known as the Roundheads), he defeated King Charles I's forces, thus bringing to an end the absolute power of the English monarchy.