its various sections were willing to receive orders (The Marquess of Ormondes Answer to the Declaration &c., in Cox, vol. ii.) He endeavoured to bring the army to Ormonde's assistance while Cromwell was marching on Wexford. Owen Roe died on 6 Nov. Daniel was proposed as his successor, and the nobility and gentry were generally in his favour; he was also supported by Ormonde, but as a protestant he was obnoxious to the papal party, and Heber or Emer MacMahon [q. v.], bishop of Clogher, who had promised, if elected general, to hand over the command to O'Neill, made his conversion an absolute condition (Henry O'Neill's Diary in Lodge, Desiderata Cur. Hib.; Carte, Life of Ormonde, iii. 532). O'Neill declined to abjure his faith; the royalist cause in Ireland was now hopeless, and O'Neill sought terms from Ireton, who gave him permission to enlist five thousand Irish troops for the service of Spain or the States-General (O'Neill to the Marchioness of Ormonde in Carte, Original Letters, i, 384-90).
O'Neill arrived at the Hague just in time to accompany Charles II, who embarked at Terheyden on 2 June 1650 for Scotland. As in the case of most of Charles's followers, his expulsion had been already voted by the Scottish parliament. Falling into the hands of the Scots, he was accordingly expelled, but was first forced to sign a document consenting to his death if ever he returned. In October he was back at the Hague pressing his services upon the Spanish ambassador. He stipulated for the command of all the Irish in the Spanish dominions, with the rank of colonel-general. This was apparently refused; and after a visit to Paris, O'Neill, in April 1651, again joined Charles in Scotland (Nicoll, Diary of Transactions, Bannatyne Club, p. 52). Charles was now practically at liberty to choose his own followers. O'Neill remained in Scotland throughout the summer, and joined in the Scottish invasion of England; he was at Penrith on 8 Aug., but he ridiculed the idea of invading England while Charles was utterly unable to hold Scotland (Cary, Memorials of the Civil War, ii. 306). After the battle of Worcester on 3 Sept. he made his escape to the Netherlands.
From this time he was the busiest of the exiled intriguers, and his journeys in Holland, Flanders, France, and Germany were incessant. He was principally attached to the princess royal, but as groom of the bed-chamber to Charles II his influence was considerable; at one time Nicholas complained that O'Neill directed all the correspondence of the court. In 1652 he was in England; in March 1654-5 he paid another visit to estimate the prospects of a royalist rising Landing at Dover, he proceeded to London, where, after interviewing the principal royalists, he was arrested, but soon made his escape to Holland. In the same year his expulsion from France was stipulated in the treaty between Cromwell and Mazarin. In February 1657-8 he set out with Ormonde from Cologne, landed at Westmarch in Essex, and, leavmg Ormonde at Chelmsford, proceeded to London, whence he returned in safety to Flanders. In August 1659 he accompanied Charles through France to Fuentarabia, and returned with him to Brussels in November.
At the Restoration O'Neill received numerous rewards for his loyal exertions; he was made captain of the king's own troop of horse-guards, became M.P. for St. Ives, and was admitted a member of Gray's Inn. His numerous grants of land, in London and elsewhere, included one of fourteen hundred feet in length and twenty-three feet broad between St. James's Park and Pall Mall; he was also sole manufacturer of gunpowder to the crown, and accountant for the regulation of alehouses. He received a pension of 500l. and a grant of the profits of all mines north of the Trent, the working of which he had investigated as early as 1641 (Cal. State Papers, Dom. 1641-3, pp. 12, 13, 1660-1). In March 1662-3 he became postmaster-general; he paid 21,500l. annually for the lease, in return for which he had a monopoly of carrying letters, with liberty to make as much as he could from it provided he adhered rigidly to the rates fixed by parliament; he was also empowered to make contracts with foreign postmasters for the transmission of letters abroad (Cal. State Papers, Dom. 1661, &c.; Joyce, Hist. of Post Office, pp. 33-4). With the wealth he thus acquired he built Belsize House, Hampstead, 'at vast expense' (Evelyn, Diary, ed. Bray, ii. 106); he also had a country house at Boughton-Malherbe, Kent. He died on 24 Oct. 1664. Charles II, writing to the Duchess of Orleans, said: 'This morning poor O'Neill died of an ulcer in the guts; he was as honest a man as ever lived. I am sure I have lost a good servant by it.' Pepys writes: 'This day the great Oneale died; I believe to the content of all the Protestant pretenders in Ireland' (Diary, ed. Wheatley, iv. 273-4; cf. also Cal. State Papers, Dom. 1664-5, pp. 43, 49; Edward Savage to Dr. Sancroft in Harl. MS, 3785. f. 19). He was buried in Boughton-Malherbe church, and his tomb was subsequently removed within the altar rails, but it no longer exists; a full inscription on it stated