During the action the frigates outmanoeuvred the much larger French vessel and drove it onto shore in heavy seas, resulting in the deaths of between 400 and 1,000 of the 1,300 persons aboard.

During the operation, the French fleet was beset by poor coordination and violent weather, eventually being compelled to return to France without landing a single soldier.

This army of 18,000 French soldiers was intended to link up with the secret organisation of Irish Republicanism known as the United Irishmen and provoke a widespread uprising throughout the island.

[1] Led by Vice-Admiral Morard de Galles, General Lazare Hoche and leader of the United Irishmen Wolfe Tone, the invasion fleet included 17 ships of the line, 27 smaller warships and transports, and carried extensive field artillery, cavalry and military stores to equip the Irish irregular forces they hoped to raise.

[2] Morard de Galles planned to sail his fleet from the French naval fortress of Brest under cover of darkness on the night of 15–16 December.

This succeeded in confusing the French officers, causing the Séduisant to strike the Grand Stevenent rock and sink with the loss of over 680 men from a complement of 1,300.

[10] For more than a week the fleet waited for a break in the storm, until Bouvet abandoned the invasion on 29 December and, after a brief and unsuccessful effort to land at the mouth of the River Shannon, ordered his scattered ships to return to Brest.

[10] Recognising that the weather was still too violent for a landing to be made, Lacrosse acknowledged the failure of the operation and ordered the ship to return to France, capturing the British privateer Cumberland en route.

While the rest of the Channel Fleet had been pursuing the French without success, Pellew had had his ships refitted and resupplied at Falmouth so that both frigates were at full complement, well armed and prepared for action.

He knew that his ship was far larger than either of his opponents, but had earlier spotted sails to westwards he believed to be British and thus considered himself outnumbered and possibly surrounded.

[14][16] In addition, Lacrosse was concerned by the increasing gale and rocky lee shoreline, which posed a considerable threat to his over-laden vessel, which was already damaged from its winter voyage and carried a demi-brigade of the French Army and Humbert, neither of which could be placed at risk in an inconsequential naval action.

An Atlantic gale swept the Ushant headland, driving a blizzard eastwards and whipping the sea into a turbulent state, making steering and aiming more difficult.

[17] Pellew was aware that his frigate was heavily outclassed by his much larger opponent, and that Amazon, which was 8 nautical miles (15 km) distant, was not large enough to redress the balance when it did arrive.

He correctly assumed, however, that the ocean was too rough to allow Lacrosse to open his lower gunports without the risk that heavy waves would enter them and cause Droits de l'Homme to founder.

[21] Approaching the larger French ship with all sail spread, Reynolds closed to within pistol shot before raking Droits de l'Homme.

[22] By 20:30, the frigates had returned to the much slower French ship and began weaving in front of Droits de l'Homme's bow, repeatedly raking her.

Observing the battered state of their opponent, Pellew and Reynolds closed on the stern quarters of the French ship, maintaining a high rate of fire that was sporadically returned by Droits de l'Homme.

[23] With their opponent almost immobilised, the British frigates were able to remain outside her arc of fire, effect repairs when necessary and secure guns that had broken loose in the heavy seas.

[25] For the rest of the night the three battered ships remained locked in a close range duel, until suddenly, at 04:20 while it was still dark, land was spotted just 2 nautical miles (3.7 km) to leeward by Lieutenant George Bell of the Indefatigable.

Although both ships had suffered severe damage from the battle and weather, they were able to make the turn away from land, Amazon to the north and Indefatigable, at the insistence of its Breton pilot, to the south.

[30] The final anchor was deployed, but it failed to restrain the ship and at 07:00 (according to the French account), the Droits de l'Homme struck a sandbank close to the town of Plozévet.

The Droits de l'Homme lay on her side directly opposite the town of Plozévet, with large waves breaking over her hull; 2 nautical miles (3.7 km) to the north, Amazon stood upright on a sandbar, her crew launching boats in an effort to reach the shore, while Indefatigable was the only ship still afloat, rounding the Penmarck rocks at the southern edge of the bay at 11:00.

The remaining crew, including those wounded in the previous night's action, were safely brought ashore by 09:00, where they were made prisoners of war by the French authorities.

[31] On the morning of 15 January, a small boat carrying nine British prisoners (part of the crew of the Cumberland, captured by Droits de l'Homme earlier in the campaign) managed to reach shore.

[34] By the evening, the remaining survivors, without food or fresh water, began to succumb to exposure, and at least one officer drowned in a desperate attempt to swim to shore.

Throughout the night, the survivors gathered on the less exposed parts of the hull, and, in the hope of staving off death by dehydration, drank sea water, urine, or vinegar from a small barrel that had floated up from the hold.

[40] Reynolds and his officers were exchanged for French prisoners some weeks later, and in the routine court-martial investigating the loss of their ship were honourably acquitted "with every sentiment of the court's highest approbation.