Shortly after the restoration the EARL OF ARRAN obtained an appointment in the household of King Charles II.,[24] and after remaining some time at court, he was sent with a congratulatory communication to the French Monarch, and served two campaigns with the French army in the capacity of aide-de-camp to Louis XIV. In 1685, when the Earl of Argyle raised the standard of rebellion in Scotland, the EARL OF ARRAN took an active part against the insurgents: he also raised a troop of horse for the service of King James II., who appointed him Colonel of the SIXTH REGIMENT OF HORSE, now FOURTH, OR ROYAL IRISH DRAGOON GUARDS. He was nominated a Knight Companion of the Thistle, on the revival of that Order in 1687, and in the following year he was promoted to the rank of Brigadier-General, and appointed Colonel of the Royal Regiment of Horse Guards. At the Revolution his conduct was remarkable for the unshaken fidelity which he evinced to his sovereign under all circumstances. When he could no longer serve the King in a military capacity, he performed his duty as gentleman of the bed-chamber, and attended His Majesty from the time of his departure from London to the moment of his embarkation at Rochester; and at the meeting of the Scottish nobility and gentry in London, in January, 1689, at which the duke, his father, presided, he expressed himself in reply to the request of the Prince of Orange for advice:--'The surest way to heal the breach is to address His Majesty to return from France, and call a free parliament. I can distinguish between his popery and his person: I dislike the one; but I have sworn, and do owe, allegiance to the other.' He had previously been removed from his regiment by the Prince of Orange.
During the hostilities which followed the accession of William and Mary, the EARL OF ARRAN did not appear in arms in favour of King James; but he was suspected of corresponding with the court of France, and was twice committed a prisoner to the Tower of London: he was, however, discharged without being brought to trial. After the decease of his father the dukedom of Hamilton reverted to his mother, in whom it was hereditary; but she resigned that honour in favour of his lordship, who was created DUKE OF HAMILTON, by patent, dated the 10th of August, 1698. His grace adhered, privately, to the interest of King James and the Pretender, until his decease, which was tragical, being killed in a duel with Lord Mohun, who was also slain at the same time in Hyde Park, on the 15th of November, 1712.