Barry Ignatius McCool was an Irishman involved in the Irish Rebellion of 1798. Some captured members were given the choice of prison or serving in the British armed forces, which McCool chose the navy and was read aboard HMS Renown, Captain James Sawyer commanding, under the pseudonym O'Shaughnessy. He later deserted the ship off the coast of France and later was reported to be in Paris. McCool was aboard the French brig Espérance when it was captured by the Channel fleet.
McCool came under immediate court-martial and hung for his crimes, leaving behind a sea chest and letter and poem he wrote to his widow which Lieutenant Hornblower promised to send to her. Hornblower discovered the poem contained coded instructions to open a secret compartment in the chest which contained money and a draft for printed bills to fuel another rebellion of the Irish. When he discovered McCool wasn't married, he disposed the of the chest over the side, as he felt enough blood had been split in Ireland already.