Hamilton, James (d. 1734), 6th earl of Abercorn , soldier and politician, was the eldest of three surviving sons of Colonel James Hamilton of Donalong, Co. Tyrone, and his wife, Elizabeth Colepeper, daughter of John, Lord Colepeper, a courtier to Charles I and Charles II. His father, a nephew of the duke of Ormond (qv), was a groom of the bedchamber to Charles II, and in 1666 was returned to the Irish parliament for the borough of Strabane. He was colonel of a regiment of foot and died on 6 June 1673, after being struck by Dutch fire while on board ship; his widow (a maid of honour to Mary, princess of Orange) and his sons were immediately granted pensions.
In 1678 and 1680 James Hamilton and one of his brothers were given passes to go to France for their education; and in 1680 he was made a groom of the bedchamber. A privy councillor to Charles II and James II (qv), he held the rank of captain or colonel under James, but changed allegiance to William of Orange (qv), and brought supplies to Londonderry in 1689 while it was besieged by Jacobite forces, among whom was his uncle Richard Hamilton (qv).
A member of parliament for Co. Tyrone (1692–3, 1695–9), in June 1701 he succeeded, on the death of his cousin, as 6th earl of Abercorn in the Scottish peerage, and also as baron of Strabane in the Irish peerage; in the same year he was created Baron Mountcastle and Viscount Strabane in the Irish peerage and appointed to the Irish privy council. He took his seat in the Scottish parliament in 1706, and consistently supported the union. His politics were whig while he sat in the house of commons, and remained so for some time after he took his seat in the Irish house of lords, but in later sessions he moved to the tory side. He was one of the most active lay peers in the house until the 1720s, and was patron of the parliamentary boroughs of St Johnstown, Co. Donegal, and Strabane, Co. Tyrone.
In 1702 he was summoned before the English house of commons to answer for his role in organising a remonstrance against the operation in Ireland of the Act of Resumption. A lighthouse patent and related pension of £500 a year, conveyed to him by his father-in-law as part of his marriage settlement, were investigated in 1703 by the house of commons, which complained that the lighthouses were neglected; he surrendered both in return for £3,000. A patent he held to all mines in Ireland (granted in 1687 in succession to previous patents held by his grandfather and father) was an obstacle to several attempts by the Irish parliament to legislate to encourage the opening of mines until, as part of a measure enacted in 1705, his rights were bought out for £4,000.
Hamilton displayed great energy during a lengthy career in public life, though his individualism verged on eccentricity. After his death (on 28 November 1734) Sir John Perceval (qv), earl of Egmont, wrote: ‘He was a man of great honour and sincerity, courage and breeding, and of as much public spirit as I ever was acquainted with, but passionate and of no great depth of understanding, yet very passable with mankind by reason of his virtues’ (Egmont diary, ii, 135).
He married, in 1684, Elizabeth, only daughter of Sir Robert Reading of Dublin and Jane Reading (née Hannay). They had nine sons and four daughters, a circumstance which added to his recurrent money worries. The eldest surviving son, James (1686–1744), who succeeded as 7th earl, was a privy councillor in both kingdoms; the sixth son, George (d. 1775), was a member of the Irish parliament (St Johnstown, 1727–60) and the British parliament (1734–5, 1747–54). Their youngest daughter Jane (d. 1753) married Lord Archibald Hamilton, a member of the household of Frederick, prince of Wales, whose mistress she became.
The ninth son, Charles Hamilton (1704–86), baptised in Dublin, educated at Westminster and Oxford, made two lengthy Italian tours while in his twenties, and brought antique sculpture back to England. He was a member of the Irish parliament which lasted all of George II's reign (Strabane, 1727–60), but never attended the house. He sat in the British parliament (1741–7), and held a post (1738–47) in the household of the prince of Wales, obtained through the influence of his sister. He was receiver general in Minorca (1743–57) and, on the loss of this post, his influential friend Henry Fox arranged for him a secret service pension. His principal interest from the mid-1730s was the creation of a renowned landscaped park at Painshill in Surrey, and advising friends on similar projects. He was obliged to sell Painshill in 1773, and spent his later years at Bath, where he died. His gardens subsequently fell into neglect, but were extensively restored in the twentieth century.