Arthur had fought for the Jacobites in the Williamite War and had gone to France as the colonel of Dillon's Regiment with Mountcashel's Irish Brigade in April 1690 when Irish troops were sent to France in exchange for French troops sent to Ireland under Antoine Nompar de Caumont, duc de Lauzun.

His father's family was Old English and descended from Sir Henry Dillon, who came to Ireland with Prince John in 1185.

[3] Henry's mother was a daughter of Ralph Sheldon, an English Catholic and an equerry to James II.

His elder brother Charles played an important role in his life as he would precede him in the viscountcy and in the colonelcy.

[6] While a child, Henry lived with his mother at the court in exile of James Francis Edward (the old pretender) at the Château-Vieux de Saint-Germain-en-Laye.

[9] Dillon's Regiment, led by Henry's father, fought for France in the War of the Spanish Succession (1701–1714).

[10] However, in 1713 Louis XIV signed the Peace of Utrecht recognising the Hanoverian succession and ending its support for the Jacobites.

[19] In 1722 James Francis Edward, who now resided at the Palazzo del Re in Rome,[20] created Henry's father Earl of Dillon.

Henry fought under his elder brother Charles at the sieges of Kehl (1733) and Philippsburg (1734) where Berwick was beheaded by a cannonball.

[29][30] On 24 October 1741 Henry's elder brother Charles, the 10th Viscount and colonel of Dillon's Regiment, died in London without surviving children.

[37] Being a peer of Ireland, Dillon resigned the colonelcy in favour of his younger brother James and left France in 1744 as England prepared a law to forbid its citizens to fight for foreign countries.

Henry and Charlotte had at least seven children: Dillon's brother James commanded the regiment as colonel-proprietor from 1744 to 1745 when he was killed in the Battle of Fontenoy[52] fighting under Maréchal de Saxe for France against the English under the Duke of Cumberland.

He continued to fight with the regiment under de Saxe against the English under Cumberland, but in 1747 he was wounded at the Battle of Lauffeld, taken prisoner, and died.

Eventually, Louis XV allowed Dillon, to serve a second term as colonel, even if absent abroad.

[58] However, Henry and Charlotte never went to live at Ditchley House, which was probably inhabited by the last Earl's widow, Catharine, who survived until 1784.