Dillon

Dillon. The family supposedly originated with Sir Henry de Leon's coming to Ireland as Prince John's secretary in 1185. He was granted lands in Longford, Westmeath, and Kilkenny. This marcher family—Gaelicized clients of the earls of Kildare at the end of the Middle Ages—managed to establish three noble lines as a result of crown service during the Tudor conquest.

Sir James Dillon (d. 1642), whose father Lucas was a prominent Elizabethan privy counsellor, benefited from the minor Jacobean plantations and was created earl of Roscommon (1622). His son Robert, 2nd earl (d. 1642), conformed, served as lord justice three times, and married his heir James, 3rd earl (c.1605–1649), to Wentworth's sister. After the Restoration, the family regained their estates under the Act of Settlement. The last earl died in 1850.

Other branches established themselves in Connacht. Theobald Dillon went there c.1580 as collector of Composition, acquired the Mac‐Costello clan lands, and became Viscount Dillon (1622). His daughter Cecily co‐founded the Poor Clare nuns in Ireland (1629). The 12th viscount conformed in 1767, married into an English aristocratic family, and became an absentee. Thomas Dillon, another Elizabethan presidency official, bought Clonbrock from the O'Connors in Galway. This line, which conformed in the early 1700s, was ennobled in 1790 and died out in 1926.

Other Dillons were Jacobites, and many saw service in the famous Dillon regiment in the French army.

Hiram Morgan