Nevertheless, on 25 Oct. 1793, he was raised to the Irish peerage as Baron O'Neill of Shane's Castle, and advanced to the rank of viscount on 3 Oct. 1795.
When in the spring of 1798 the rebellion broke out in the north of Ireland, O'Neill was governor of Antrim. Having received intelligence of the intended outbreak while in Dublin, he summoned by public notice the county magistrates to meet him at Antrim on 7 June. Thereupon the rebel leaders resolved to attack the town of Antrim on the same day, and to seize O'Neill and the magistrates. O'Neill slept at Hillsborough on the night of 6 June, while on his way from Dublin, and, having passed through Lisburn unrecognised early next morning, arrived at Antrim soon after noon. His servants, who followed him, were robbed of their arms.
The rebels attacked the town before the greater part of the reinforcements promised by General Nugent had arrived. During the engagement O'Neill was in the main street with a party of dragoons. After the enemy had gained a temporary advantage, Colonel Lumley ordered a retreat of the troops within the town towards the Lisburn road, along which reinforcements were advancing. O'Neill's horse was disabled, and he was left behind in the town. Here he was knocked down by one of the rebel pikemen (according to one account, his own park-keeper), and, after shooting one of his assailants, was mortally wounded. He died on 18 June at Lord Massereene's castle in the neighbourhood (cf. a full account in Charlemont Papers, ii. 325–6, 328–9).
Sir Jonah Barrington speaks of O'Neill's ‘portly and graceful mien,’ and adds that he was ‘high-minded, well-educated, his abilities moderate, but his understanding sound; incapable of deception; one of the most perfect models of an aristocratic patriot.’ Musgrave bears testimony to other amiable qualities, and to the fact that he was charitable in all senses of the word. Grattan's son calls O'Neill ‘a high-spirited and independent member;’ but Lord Charlemont, in a letter to Richard Jephson, dated 4 Dec. 1793, while admitting that ‘it is impossible not to love O'Neill,’ speaks of the great fault in his character—‘his too great pliancy’—the cause of which was his ‘milkiness of disposition’ (Hardy, Life of Charlemont, ii. 322; Charlemont Papers, ii. 225). O'Neill married on 18 Oct. 1777 Henrietta, only child of Charles Boyle, lord Dungarvan, son of John Boyle, fifth earl of Cork and Orrery. She died on 3 Sept. 1793, leaving two sons, both of whom were successively Viscounts O'Neill.
A portrait was painted by Peters, and engraved by Reynolds. Another, engraved by Maguire, is in ‘Walker's Hibernian Magazine’ for August 1798, where also are printed some highly eulogistic memorial verses by Amyas Griffith, esq., ‘who for a series of years (since his Misfortunes in the year 1785) has existed by his unsolicited bounties.’
Charles Henry St. John O'Neill, second Viscount and first Earl O'Neill (1779–1841), elder son of the first viscount, was born 22 Jan. 1779. He was educated at Eton and Oxford, matriculating at Christ Church 23 Nov. 1795. Lord Cornwallis, in a letter to the Duke of Portland of 3 June 1800, recommended that he and Lord Bandon should have precedence in the creation of Irish earls then contemplated. On 7 Aug. O'Neill accordingly became Viscount Raymond and Earl O'Neill. His borough of Randalstown was disfranchised at the union (Cornwallis Corr. 2nd ed. iii. 245, 319, 323). In September he was elected one of the first Irish representative peers in the imperial parliament. In 1807 he was appointed joint postmaster-general of Ireland. On 13 Feb. 1809 he was created a knight of the order of St. Patrick. In 1831 he became lord-lieutenant of Antrim. He was also grand master of the orangemen of Ireland until the union of the English and Irish bodies under the Duke of Cumberland. He died unmarried at the Bilton Hotel, Sackville Street, Dublin, on 25 March 1841. The earldom then became extinct, the viscounty devolving on his younger brother.
John Bruce Richard O'Neill, third Viscount (1780–1855), was born on 30 Dec. 1780. He entered the army as an ensign in the Coldstream guards on 10 Oct. 1799, saw much active service, and attained the rank of major-general 27 May 1825, lieutenant-general 28 June 1838, and general 20 June 1854. He also represented the county of Antrim from 19 July 1802 till his succession to the peerage on the death of his brother in 1841. He supported the Reform Bill, but took little part in public affairs. He was re-elected on 15 May 1811, after his appointment as constable of Dublin Castle, and also on 9 May 1812, ‘he having vacated his seat by sitting and voting without having taken the oaths’ (Official Returns Memb. Parl.) In February 1842 he was elected a representative peer of Ireland. Besides being constable of Dublin Castle, he was vice-admiral of the coast of Ulster. He died of a complication of gout and influenza at Shane's Castle on 12 Feb. 1855.
The name of O'Neill was assumed by the inheritor of the estates, the Rev. William