She sortied again two days later in an attempt to recover some of the prizes, but the fleet lost more ships than they regained, and Neptune had to be towed back to harbour.

[1] Neptune joined the rest of the Toulon fleet preparing to sail for the West Indies on 21 October 1804 under the command of Vice-Admiral Pierre-Charles Villeneuve.

Villeneuve struggled on, but bad weather in the Gulf of Lyons dispersed his fleet, and fearing an attack on his disorganised forces, returned to Toulon three days after setting out.

[4][6] Nelson spent nearly six weeks sailing back and forth across the Mediterranean through heavy seas while the French remained in port, before news finally reached him of Villeneuve's location.

[1] Neptune formed part of Villeneuve's division, consisting of the flagship, the 80-gun Bucentaure, and the 74-gun ships Pluton, Mont Blanc, Berwick and Atlas.

[9] The other division was commanded by Rear-Admiral Pierre Dumanoir le Pelley, flying his flag aboard the 80-gun Formidable, and accompanied by the 80-gun Indomptable, and the 74-gun ships Swiftsure, Scipion and Intrépide.

[1] After resupplying briefly at Cadiz, the fleet sailed to the West Indies, arriving at Fort de France, Martinique on 14 May, where they were joined over the next two days by six Spanish ships of the line and a frigate under Frederico Gravina.

The combined fleet achieved little while in the West Indies, managing only to capture the British-held Diamond Rock after two weeks of sitting idle at anchor.

Villeneuve was instructed to attack and capture the British colonies in the West Indies, before sailing his entire force back to Europe, join Ganteaume at Brest and cover the invasion flotilla.

[11] Villeneuve gathered his forces and pressed northwards towards Antigua, but on 7 June he came across a lightly defended convoy of British merchants, and captured several of them the following day.

[13] Villeneuve formed up the line of battle, with Neptune being eleventh from the front, positioned astern of the Berwick and ahead of the Bucentaure.

This would be significant in the coming battle as the position astern of the flagship would be the focus of British attention, and should have been occupied by a powerful ship like the Neptune.

Redoutable's captain, Jean Jacques Étienne Lucas, saw the threat, and brought his ship forward in an attempt to close the gap.

[16] As the battle started Nelson's flagship, HMS Victory broke the line ahead of Neptune, passing by and raking Bucentaure.

[17] Standing someway off to leeward Neptune's gunners reloaded, and then opened fire with a broadside into HMS Temeraire as the British ship came up through the gap created by Victory's passage.

[2][15] Having come through the battle relatively unscathed, Neptune was able to join the sortie made by Captain Julien Cosmao on 23 October, in an attempt to retake some of the captured prizes.

The Neptuno ran aground and was destroyed, while a similar fate befell both the Indomptable, after she grounded off Rota, and the San Francisco de Asis, in Cadiz Bay.

He attempted to move his fleet, consisting of the Neptune, the 74-gun ships Héros, Pluton, Algesiras and Argonaute and the 40-gun frigate Cornélie, out of the harbour, but on 9 July the squadron was attacked by Spanish forces from the land and sea.