chief of division, commanding the Jemmapes in the Mediterranean. From 1801 to 1803, he served under Dordelin in Saint-Domingue, commanding the , the Alliance and the . Back to France, he assumed command of the 74-gun Pluton in the squadron of Admiral Villeneuve in Toulon. He accompanied the squadron to the Caraibs in its seizing of the English fortress of the Diamond Rock, away from Martinique. Back to Europe, he took part in the Battle of Cape Finisterre, on 22 July, saving one Spanish ship which had been cut off for a time by the British. Battle of Trafalgar At the Battle of Trafalgar, Pluton was part of the reconnaissance squadron created by Villeneuve and commanded by Spanish Admiral Gravina. She followed the in the line of battle, in the rear. When Admiral Collingwood attacked, Pluton opened fire on , then manoeuvered in order to block HMS Mars, damaged her with artillery fire and attempted to board and seize her. However, the arrival of in her stern forced her to turn. She engaged , already damaged by the fire of Fougueux; again another English ship, , forced her to disengage. She then helped the surrounded of Gravina, and succeeded in freeing her. However, at this point, the battle was already lost for the French. At sunset, five French ships (, , , and and six Spanish ships tried to return to Cádiz, under dying Admiral Gravina. On 23 October, Cosmao, as one of the most senior officers present, jointly took command of the squadron with Spanish Commodore Enrique MacDonell, and set back to sea with five ships: Pluton, Héros, Neptune, San Francisco de Asis, and Rayo. Cosmao later tried to claim sole credit for the sortie but this is not correct as both MacDonell and Cosmao both had Commodore pennants raised. He managed to retake Neptuno and Santa Ana, as well as to force the English to scuttle a number of their prizes. Neptuno and Rayo sank during the journey back and the Indomptable was wrecked with the loss of over a thousand men. Late career Cosmao-Kerjulien was made Rear Admiral on 29 May 1806. He took command of a division of the French Mediterranean Fleet, under Ganteaume from 1807. he took part in operations to resupply Corfu and to the landing in Sicily. His 4 ships, having sustained damage, retreated to Taranto. In late 1809, Ganteaume was organising reinforcements