Chichester, Arthur (1606–75), 1st earl of Donegall , soldier, and administrator, was born 16 June 1606, eldest son of Edward Chichester (brother of Arthur Chichester (qv) (1563–1625)) and his wife Anne (née Coplestone) of Devon. He was thus heir to the largest Ulster estate after that of the earl of Antrim. In 1625 the king reserved for him ‘as a special mark of our favour’ the first vacant command of an infantry or cavalry unit in Ireland; Chichester took over a troop of horse in 1627 and retained military command for most of the rest of his life. He sat for Co. Antrim in the Irish parliament (1634, 1640–47). When hostilities began in 1641 he raised troops, became joint commander in Antrim (November), and commanded cavalry under the Scots general Robert Monro (qv). In 1644 he became governor of Belfast and a member of the Irish council. However, in May 1644 Monro expelled Chichester and his garrison from Belfast for opposition to the Scottish covenant, and for collaboration with the marquess of Ormond (qv). At Ormond's recommendation, Chichester was created earl of Donegall (30 March 1647); he did not take his seat as a peer till the restoration, when he also rejoined the council, took up the governorship of Carrickfergus vacated by his father's death (1648), was confirmed in properties granted to his uncle, and reported on the loyalty of others during the interregnum. In May 1666 his Carrickfergus garrison (suffering, like others, from lack of pay) mutinied, surrendered to Richard Butler (qv), 1st earl of Arran, and were punished with hanging or transportation by Ormond, who may have seen Donegall as having mismanaged the affair.
A keen racehorse owner, Donegall also fostered education and founded a mathematics lecture at Dublin University (1668). He died at Belfast 18 March 1675, and was buried at Carrickfergus on 20 May. He married first Dorcas Hill (d. 1630) of Honiley, Warwickshire; secondly Mary Digby (d. 1648), daughter of the earl of Bristol; and thirdly Laetitia Hickes (d. 1691) of Essex. His daughter Mary, only child of his first marriage, married John St Leger, ancestor of the Viscounts Doneraile; his daughter Anne, only surviving child of his third marriage, married first John Butler (1643–76), earl of Gowran, and secondly Francis Aungier (qv), 1st earl of Longford. No children of his second marriage survived; William, son of his third marriage, died young 24 December 1660.