On October 20, 1794, during a by‑election for the County Kerry seat in the Irish House of Commons, John Gustavus Crosbie — a colonel in the 22nd Foot and High Sheriff of Kerry — takes offence at remarks made by the sitting MP, Sir Barry Denny, 2nd Baronet.

Denny, who has recently inherited his father’s seat, has publicly promised to remain neutral between the rival candidates, including Crosbie and Colonel Henry Arthur Herbert. Crosbie believes one of Denny’s comments — whether real or perceived — breaches this neutrality, and he issues a formal challenge.

The confrontation culminates in a duel at Oak Park, Tralee. Crosbie, taking careful aim, shoots Sir Barry Denny through the head, killing him instantly. At the time, killing in such disputes is considered an affair of honour, though legally it is premeditated murder.

The killing shocks the political and social elite of County Kerry. Denny is about to be raised to the Peerage of Ireland as Baron Denmore when he dies. The feud between the Crosbie and Denny families is bitter and long‑lasting, lasting for generations.

Crosbie is returned as MP for Kerry following the by‑election, but he dies suddenly on July 6, 1797 after falling from his horse. Local tradition holds that he was poisoned by the Denny family in revenge for the duel.

This incident remains one of the most notorious episodes in 18th‑century Irish political history, illustrating the intense personal rivalries and honour‑driven violence that often accompanied parliamentary contests in Ireland at the time.