John Hamilton, 1st Marquess Of Abercorn

John James Hamilton, 1st Marquess of Abercorn (2 July 1756 – 27 January 1818), was an Anglo-Irish peer and politician. He was born in London, the posthumous son of Captain Hon. John Hamilton, the second son of the 7th Earl of Abercorn, and his widow Harriet. His father drowned in an accident at Portsmouth Harbour seven months prior to his birth. He was baptized at St George's, Hanover Square.

Hamilton's education included attendance at Harrow School from 1770 to 1771. He was admitted to the Inner Temple on 15 June 1773, though his stay was brief; subsequently, he was admitted to Pembroke College, Cambridge on 30 July 1773. He matriculated at Michaelmas and earned his Master of Arts degree in 1776. During his time at Cambridge, he formed a friendship with William Pitt the Younger, a relationship that had significance in his later political career.

Around 1781, Hamilton traveled abroad and returned in late summer 1783. Through the influence of John Buller, his wife's uncle, he was elected as a Tory Member of Parliament for East Looe in December 1783, succeeding William Graves. His maiden speech opposed the East India Bill of the Fox–North Coalition. He supported William Pitt the Younger’s first ministry. At the 1784 general election, Hamilton was elected for St Germans, a borough in Cornwall, by his half-brother Edward Eliot. Although he was a supporter of Pitt, Hamilton demonstrated independence and retained a degree of his uncle's stiff pride. He was a supporter of Warren Hastings and opposed legislation that aimed to regulate and sanction the slave trade, speaking against such bills in 1788 with a stance favoring abolition.

On 9 October 1789, Hamilton succeeded his childless uncle as Earl of Abercorn and entered the House of Lords, taking the courtesy title Viscount Hamilton. He was created the 1st Marquess of Abercorn on 15 October 1790. He was sworn into the Privy Council of Ireland on 7 February 1794. As much of the Abercorn estates were in Ireland, he sought to consolidate influence by building a voting bloc within the Irish Parliament from County Donegal and County Tyrone, though with limited success. He was criticized for his treatment of tenants and unsuccessfully attempted to remove a High Court judge in 1805, whose conduct was described as reckless.

Hamilton was invested as a Knight of the Garter on 17 January 1805. His character has been described in historical sketches; he was known to conduct shooting parties wearing the Order of the Blue Ribbon and was particular about his household staff, requiring housemaids to wear white kid gloves when making his bed. Prior to his marriage to his first cousin Miss Cecil Hamilton, he influenced the Crown to grant her the rank of an Earl’s daughter, aiming to improve her social standing. When she contemplated eloping, Hamilton reportedly urged her to take the family coach to avoid scandal.

Hamilton's first marriage was to Catherine Copley, daughter of Sir Joseph Copley, 1st Baronet, on 20 June 1779 at St Marylebone. They had six children: Lady Harriet Margaret, Lady Katherine Constantia, Lady Catherine Elizabeth, Lady Maria, James Hamilton (Viscount Hamilton), and Lord Claud Hamilton. Catherine died in 1791.

He married his first cousin, Lady Cecil Hamilton, daughter of Rev. Hon. George Hamilton, on 4 March 1792. She received a Royal Warrant of Precedence to assume the rank of an earl’s daughter. Their marriage was reportedly not successful, and they separated in 1798 before divorcing by Act of Parliament in April 1799. Lady Cecil subsequently married Joseph Copley, brother of Hamilton’s first wife. Their union produced one child, Lady Cecil Frances Hamilton.

His third marriage was to Lady Anne Jane Gore, daughter of Arthur Gore, 2nd Earl of Arran, on 3 April 1800. Hamilton died at Bentley Priory near Stanmore on 27 January 1818. He was buried in Stanmore. His titles were inherited by his grandson, James Hamilton.