This ship was the 74-gun Hercule under Captain Louis Lhéritier, newly commissioned at Lorient and sailing to Brest to join the main French fleet and the British squadron immediately changed direction to intercept the new target.

At 21:15 Mars reached Hercule, coming under heavy fire as Hood manoeuvred into position, bringing his ship crashing alongside the French vessel.

Both L'Héritier and the deceased Hood were highly praised for their conduct during the battle, which is noted as being a very rare example during this period of an action between two ships of approximately equal strength without any external influence.

This made French maritime journeys extremely hazardous even in inshore waters: in June 1795 the main French fleet had suffered a defeat at the hands of the blockade force at the Battle of Groix in the approaches to the port of Lorient,[2] while at the action of 13 January 1797 the independently sailing 74-gun ship of the line Droits de l'Homme was driven ashore and destroyed in the approaches to Brest by two frigates of the blockade squadron.

[3] On 12 April 1798 the British blockade fleet under the command of Admiral Lord Bridport sailed from its winter anchorage at St Helens on the Isle of Wight for the Breton coast.

[4] The French fleet had suffered a series of setbacks in the early years of the war: in addition to the losses at Groix, seven ships had been lost at the Glorious First of June in 1795 and more were wrecked during the failed Croisière du Grand Hiver operation of 1795 and the Expédition d'Irlande in 1796.

[6] On 20 April L'Héritier was ordered to take Hercule on her maiden voyage, the short journey northwest along the coast to join the main fleet under Vice-Admiral Morard de Galles at Brest, where the crew would be augmented to reach the full complement.

[10] At 20:30, L'Héritier recognised that the current was too strong for Hercule to successfully navigate the Raz de Sein and instead anchored at the mouth of the channel with a spring on his cable, a system of attaching the bow anchor that increased stability and allowed L'Héritier to swing his broadside to face the enemy while stationary,[9] roughly 2 nautical miles (3.7 km) southwest of Pointe de Raz and about 21 nautical miles (39 km) from his destination at Brest.

[6] Casualties were heavy on both sides: 20 minutes after the action began a musket ball struck Hood in the thigh, severing his femoral artery.

[16] The lighting of Hercule had gone out at the beginning of the engagement, leaving her crew confused, and as a result, only around 40 men answered when L'Héritier ordered the boarding;[17] he was himself injured twice, to the head by a sabre and to the thigh by a pike, while leading the assault.

[18] At 10:30, after an hour of continual bombardment L'Héritier surrendered: Hercule's hull had been torn open, five guns were dismounted with others damaged and more than two fifths of the crew killed or wounded.

[12] At 22:50 Jason arrived and Stirling took charge of removing prisoners from Hercule and began the long process of extricating the two battered ships of the line from the dangerous Raz de Sein channel.

[15] Historian Robert Gardiner has noted that this "classic fight" was unusual in being fought between two single ships of the line of equal force and size without an external influence,[11] and Edward Pelham Brenton wrote in 1823 that "The meeting of two ships of the line is a circumstance of rare occurrence, and its decision in our favour a brilliant ornament to our naval history": he could only identify three other such incidents in British naval history.