The Hamilton–Mohun Duel occurred on 12 November 1712 in Hyde Park, then on the outskirts of London. The principal participants were James Hamilton, 4th Duke of Hamilton and Charles Mohun, 4th Baron Mohun. Both men died from wounds received.
Although ostensibly fought over a disputed inheritance, the duel had strong political overtones. Mohun was a prominent Whig while Hamilton had close links to the Tory government of Robert Harley. Hamilton had recently been appointed as British Ambassador to Paris where he was expected to negotiate the peace agreement that would end the War of the Spanish Succession. Mohun's political patron the Duke of Marlborough had recently been dismissed from his command, and was strongly opposed to the peace plan. This may have motivated Mohun to issue his challenge.
Mohun had developed a reputation as a violent and frequent duellist, having been involved in several fatal encounters. His father Lord Mohun had himself been killed in a duel.
Hamilton accepted Mohun's challenge to fight with swords. Hamilton selected his relation Colonel John Hamilton as his second, while Mohun employed his friend and political ally the Irish officer George Macartney. As was often customary at the time, seconds actively engaged in the combat.
The group assembled in Hyde Park very early in the morning. Once the duel began, Hamilton and Mohun went at each other "like wild beasts, not fencing or parrying". In these fierce exchanges both Mohun and Hamilton were wounded. Mohun was run through the chest, a fatal wound, while Hamilton was cut on the arm. Exactly what happened next remained contentious. Colonel Hamilton claimed that, with the duel over, he went to the assistance of the Duke who had dropped his sword. Macartney stepped forward and delivered a fatal blow to him. The Duke soon died of his wounds.