He fought for the Jacobites during the Williamite War, defending Galway against Ginkel and surrendering it in 1691 after a short siege.

[1] He was the second but eldest surviving of the three sons of Theobald Dillon and his wife Mary Talbot.

[2] His father's family was Old English and descended from Sir Henry Dillon who had come to Ireland with Prince John in 1185.

[7] In July 1687 Dillon married Frances Hamilton, second of the three daughters of comte George Hamilton and his wife Frances Jennings and step-daughter of Richard Talbot, 1st Earl of Tyrconnell, lord deputy of Ireland.

[14] His father, the 7th Viscount, fell in the Battle of Aughrim on 12 July 1691[15] fighting under Saint-Ruhe against the Williamites under Ginkel.

[21] While many of the Jacobites went into exile at the end of the war, an event called the Flight of the Wild Geese, Dillon stayed in Ireland and applied for the reversal of his attainder, which he obtained in 1694 by a judgement of the Court of the King's Bench and was confirmed by the Irish House of Lords in 1697.