Hamilton was born on 14 March 1732. He was the third son, of seven children born to Mary Dawson (daughter of Joshua Dawson) and Hon. Henry Hamilton, MP and Collector of the Port of Cork.{{cite book | last = Granville | first = Mary | publisher = Richard Bentley | title = The Autobiography and Correspondence of Mary Granville | volume = I | year = 1862 | location = London | pages = 26 }} His younger brother was Henry Hamilton, who served as royal Governor of Bermuda and Dominica.{{cite book | last = Lodge | first = John | editor = Mervyn Archdall | title = The Peerage of Ireland or A Genealogical History of the Present Nobility of that Kingdom | volume = V | location = Dublin | publisher = James Moore | year = 1789 | pages = 178 }}{{cite book |last1=Massachusetts |first1=Historical Records Survey (U S. ) |last2=Survey (Mass.) |first2=Historical Records |title=American Portraits, 1620-1825: Found in Massachusetts ... |date=1939 |publisher=Historical Records Survey |page=84 |url=https://books.google.com/books?id=Qes7i-0h4nEC&pg=PP84 |accessdate=30 April 2020 |language=en}}

His uncles were Frederick Hamilton and Gustavus Hamilton. His grandfather was Gustavus Hamilton, 1st Viscount Boyne, his great-grandfather was Sir Frederick Hamilton, and his great-great grandfather was Claud Hamilton, 1st Lord Paisley.{{cite book | last = Burke | first = John | title = A Genealogical and Heraldic History of the Peerage and Baronetage of the British Empire | publisher = Henry Colburn and Richard Bentley | location = London | volume = I | edition = 4th | year = 1832 | pages = 136 }}

Career

Hamilton entered the Irish House of Commons for St Johnstown (County Longford) in 1780 and sat for the constituency until 1783. Subsequently he was elected for Rathcormack and Clogher. He chose the latter and was a Member of Parliament for the constituency until 1795, resigning the seat to be Escheator of Munster, a notional 'office of profit under the crown'. In the following year he stood successfully for Armagh Borough, which he represented until 1798.{{cite web | url = http://www.leighrayment.com/commons/irelandcommons.htm | archive-url = https://web.archive.org/web/20080607022535/http://www.leighrayment.com/commons/irelandcommons.htm | archive-date = 7 June 2008 | title = Leigh Rayment - Irish House of Commons 1692-1800 | url-status = usurped | accessdate = 1 May 2009 }}

In 1780, Hamilton was appointed Under-Secretary to the Lord Lieutenant of Ireland. He held this post until February 1795 and again from May of the same year until 1796.{{cite book | last = Haydn | first = Joseph | title = The Book of Dignities: Containing Rolls of the Official Personages of the British Empire | publisher = Longman, Brown, Green and Longman's | location = London | year = 1851 | pages = 446 }} In 1796, he was sworn of the Privy Council of Ireland.{{cite web | url = http://www.leighrayment.com/pcouncil/pcouncilI.htm | archive-url = https://web.archive.org/web/20080607022603/http://leighrayment.com/pcouncil/pcouncilI.htm | archive-date = 7 June 2008 | title = Leigh Rayment - Privy Council of Ireland | url-status = usurped | accessdate = 1 May 2009 }}

Personal life

He married Arabella Berkeley, daughter of Reverend Dr. Robert Berkeley, Bishop of Cloyne.{{cite book |last1=Moffat |first1=R. Burnham |title=The Barclays of New York: who They are and who They are Not,-and Some Other Barclays |date=1904 |publisher=R. G. Cooke |page=[https://archive.org/details/barclaysnewyork00moffgoog/page/n388 377] |url=https://archive.org/details/barclaysnewyork00moffgoog |accessdate=30 April 2020 |language=en}}{{cite web | url = http://thepeerage.com/p14779.htm#i147781 | title = ThePeerage - Rt. Hon. Sackville Hamilton | accessdate = 1 May 2009 }} Together, they were the parents of a son:

Henry Hamilton (d. 1850), who in 1808 married Hon. Caroline Penelope Pakenham (d. 1854), a daughter of Edward Pakenham, 2nd Baron Longford, sister of Thomas Pakenham, 2nd Earl of Longford and Catherine Wellesley, Duchess of Wellington (wife of Arthur Wellesley, 1st Duke of Wellington).{{cite web |title=Longford, Earl of (I, 1785) |url=http://www.cracroftspeerage.co.uk/longford1785.htm#LONGFORD_1756_2 |website=www.cracroftspeerage.co.uk |publisher=Heraldic Media Limited |accessdate=30 April 2020}}
Rev. Sackville Robert Hamilton (d. 1853), the Rector at Mallow who married Jane Freeman, daughter of Edward Deane Freeman, High Sheriff of County Cork.

Hamilton died on 29 January 1818.

=Descendants=

Through his son Sackville, he was a grandfather of Sackville Deane Hamilton (1808–1878), who married Eleanor Sankey, and General Henry Hamilton (1812–1891), who married Isabella Freeman (a daughter of Joseph Deane Freeman).{{cite book |title=Debrett's Peerage, Baronetage, Knightage, and Companionage |date=1884 |publisher=Kelly's Directories |page=92 |url=https://books.google.com/books?id=Vlo-AQAAIAAJ&pg=PA92 |accessdate=30 April 2020 |language=en}}