Upon the death of his brother on 18 June 1679, he succeeded as the title of 3rd Earl of Drogheda, a title that had been created for his father in the Peerage of Ireland in 1661. He also succeeded to his family's subsidiary titles, as the 5th Baron Moore of Mellefont (which had been created for his great-grandfather, Garret Moore, in 1616) and the 5th Viscount Moore (created in 1622, also for his great-grandfather Garret). On the death of his sister, the Dowager Countess of Clanbrassil, who had devised upon him the Hamilton family estates in her will, he assumed the additional surname of Hamilton in 1677.[5]
He was appointed Privy Counsellor for Ireland in 1680. From 1689 to 1698, he was Colonel of a Regiment of Foot. He was attainted in his absence by the Irish Parliament of King James II in 1689, against whom he fought at the Battles of the Boyne and Limerick on the side of King William III. From 1696 to 1697 and, again, from 1701 to 1702, he served as a Lord Justice of Ireland. In 1699, he was Commissioner for forfeited estates.[6] He also served as Governor of Meath and Louth.[7]
Lord Drogheda died on 7 June 1714 and was succeeded in his titles by his grandson, Henry, as his eldest son, Charles, predeceased him.[10] His widow, the dowager Countess of Drogheda, died on 6 May 1726.[7]
^Charles Kidd and David Williamson, editor, Debrett's Peerage and Baronetage (London: Debrett's Peerage, 1999), volume 12, page 1870.
^George Edward Cokayne, editor, The Complete Baronetage, 5 volumes (c. 1900); Gloucester: Alan Sutton Publishing, 1983), volume IV, page 463.
^ abG.E. Cokayne; with Vicary Gibbs, H.A. Doubleday, Geoffrey H. White, Duncan Warrand and Lord Howard de Walden, editors, The Complete Peerage of England, Scotland, Ireland, Great Britain and the United Kingdom, Extant, Extinct or Dormant, new ed., 13 volumes in 14 (1910-1959; reprint in 6 volumes, Gloucester: Alan Sutton Publishing, 2000), volume IV, page 463.
^John Debrett, Debrett's Peerage of England, Scotland, and Ireland (1840), p.249.
