Shortly after the start of the Civil War he was "disabled" from sitting in the Long Parliament as he had joined the Royalist cause. He raised six regiments of horse and foot soldiers at his own expense and took part in the Battle of Edgehill and the Battle of Brentford, both in 1642, the First Battle of Newbury (1643), the Battle of Selby (1644), the Battle of Naseby (1645), as well as the sieges of Reading (1643), Bristol and Newark and was wounded several times. He later became Lieutenant-General of the King's forces in the North of England, and Governor of York and of Newark. At Oxford on 27 January 1645 he was raised to the peerage by King Charles I under the title of Baron Belasyse of Worlaby, Lincolnshire.