Capell was the only son of
Sir John 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, and his fate for some time hung in the balance. He succeeded in escaping from the
Tower of London, wading the moat once he had got over the walls, only to be betrayed by a
Thames waterman, who had been engaged to row him from a hiding place at the
Temple to one in
Lambeth. He was again captured and was condemned to death by parliament, on 8 March 1649, and beheaded together with the
Duke of Hamilton and the
Earl of Holland. The beheadings were carried out by
Richard Brandon in his capacity as the common hangman of London. One of Lord Capell's last requests was for
his heart to be buried with the body of King Charles I, and after his execution, Capell's heart was preserved in a silver box. The silver box was kept in the custody of the
Bishop of Winchester, and was later presented, by the Bishop, to King Charles II. In 1703, a heart in a silver box was found at Hadham Hall, suggesting that the King sent the heart to Capell's son. It was later taken to
Cassiobury, but since the dissolution and sale of the Cassiobury estate, the whereabouts of Capell's heart are now unknown. A memorial stone to Lord Capell was erected at St Cecelia's Church in
Little Hadham, Hertfordshire. ==Works==