Arthur Capell, 1st Baron Capell (20 February 16089 March 1649), of Hadham Hall and Cassiobury House, Watford, both in Hertfordshire, was an English politician who sat in the House of Commons from 1640 until 1641 when he was raised to the peerage as Baron Capell. He supported the Royalist cause in the Civil War and was executed on the orders of parliament in 1649. Life Capell was the only son of Sir Henry Capell, of Rayne Hall, Essex, and his wife Theodosia Montagu, daughter of Sir Edward Montagu of Boughton House, Northamptonshire. He was educated at Queens' College, Cambridge. In April 1640, he was elected Member of Parliament for Hertfordshire in the Short Parliament, and was re-elected MP for Hertfordshire for the Long Parliament in November 1640. At first, he supported the opposition of the arbitrary government of King Charles I of England. On 5 December 1640, he delivered the "Petition from the county of Hertfordshire", outlining grievances against the King, and continued to criticise the King and the King's advisers right through to the summer of 1641. In June 1641, in an effort to raise additional revenue, the price of baronies was reduced from £400 to £350, and Capell was raised to the peerage by the title of Baron Capell of Hadham, in the County of Hertford, on 6 August 1641. However, Capell was openly allying himself with the King's cause by early 1642, on which side his sympathies were now engaged. On the outbreak of the English Civil War, he was appointed lieutenant-general of Shropshire, Cheshire, and North Wales, where he rendered useful military services, and was later made one of the Councillors of Prince Charles Stewart (who later became King Charles II of England), as well as a commissioner at the Treaty of Uxbridge in 1645. He attended the Queen, Henrietta Maria of France (the wife of King Charles I), in her flight to France in 1646, but disapproved of her son Prince Charles's journey thither, and afterwards retired to Jersey; later, he subsequently aided in the King's escape to the Isle of Wight. Capell was one of the chief Royalist leaders in the second Civil War, but met with no success, and on 27 August 1648, together with Earl of Norwich, he surrendered to Lord Fairfax at Colchester, on the promise of quarter for life. This assurance was afterwards interpreted as not binding the civil authorities,