Cromwell played a key role during the Civil Wars and helped win a decisive victory against King Charles I at Naseby in 1645. Four years later, in 1649, he was one of the signatories on the King's death warrant. With the monarchy abolished Cromwell became Chairman of the Council of State. In 1650 he turned his attention to Scotland where Charles II had recently been crowned King of Scots. Cromwell defeated the Scottish army at Worcester and proceeded to unite the three kingdoms of England, Scotland and Ireland.