Hamilton, Sir Frederick (c.1590–1647), soldier and founder of Manorhamilton, Co. Leitrim, was born in Scotland, son of Lord Claud Hamilton, one of the leaders of Scotland's catholics in the late sixteenth century, and his wife, Margaret, daughter of George Seton, 6th Lord Seton. He had three sisters and six older brothers, three of whom – James, 1st earl of Abercorn, Sir Claud Hamilton, and Sir George Hamilton – received large land grants in Co. Tyrone in 1610–11. Although the rest of his family were catholics and Stuart loyalists, he became deeply hostile to catholicism and, despite enjoying favour under James I and Charles I (to whom he was a gentleman of the privy chamber), broke with the Stuarts in the 1640s. In 1621 he was granted lands in Co. Leitrim, where he was to establish the manor of Hamilton, and in the same year was given command of a troop of horse. About 1638 he built a large fortified house, whose ruins stand on the edge of the modern town of Manorhamilton. Constantly seeking to increase his holdings, he came into conflict with other settlers in the region, notably Sir William Cole (qv) of Enniskillen, Co. Fermanagh.
In 1631 he was granted a commission to raise 1,200 men for the service of Gustavus Adolphus, and spent about two years in the Swedish king's German campaigns. His experiences in these wars may have brutalised what was naturally a markedly aggressive and disputatious personality. Given his character and his expectation of personal access to the monarch, it was natural that he should come early into conflict with Thomas Wentworth, earl of Strafford (qv), lord deputy after 1633, who adjudicated against him in one of his lawsuits, and who, during army inspections, found fault with the company he commanded.
In 1641 Hamilton was in Ireland, at Derry, when he heard news of the rebellion, and immediately proceeded to Manorhamilton. This journey, and the subsequent semi-siege he withstood there for more than two years, are recounted in a contemporary pamphlet. He disclaimed authorship, but endorsed the contents, which certainly bear the stamp of his personality. It is accurate in essentials, despite obvious exaggerations, especially in describing the many reverses he is supposed to have inflicted on the Irish against outlandish odds. He appears as a brave and ruthless soldier but also a self-righteous braggart, who discerned divine providence in his successes. He showed utter contempt for the native Irish whom he loved to bait, and bitter resentment towards his protestant neighbours whose military efforts he judged wanting. Inevitably, he refused to observe the cessation of hostilities negotiated by the marquess of Ormond (qv) with the Catholic Confederation in 1643, thus incurring the viceroy's hostility.
At some point after the published account finishes in 1643, he left Manorhamilton (his house being burned after his departure); he was in Scotland by April 1645, and commanded a regiment in the Scottish covenanters’ army against the royal forces during 1645–6. He sought compensation from parliament for his losses in the Irish rebellion, while his dispute with Cole, whom (among other charges) he accused of collusion in the rebellion, was inquired into in 1645 by parliament, which did not find that his allegations had substance. He died in Scotland in 1647.
He had married, firstly, Sidney, daughter of Sir John Vaughan (qv), the governor of Derry. They had a daughter, Christina, and three sons, all of whom became soldiers. James and Frederick both fought in their father's regiment in 1645–6, while Frederick died in 1647 in the Irish wars, in Connacht. The youngest son, Gustavus Hamilton (qv), later 1st Viscount Boyne, achieved fame in the Irish campaigns of King William (qv). A second marriage, to Agnes, or Alice, daughter of Sir Robert Hepburn of Alderstown, in Scotland, produced no children.