Battle of Port Louis

The Battle of Port Louis was a minor naval engagement of the French Revolutionary Wars, fought on 11 December 1799 at the mouth of the Tombeau River near Port Louis on the French Indian Ocean island of Île de France, later known as Mauritius. Preneuse had originally been part of a powerful squadron of six frigates sent to the Indian Ocean in 1796 under the command of Contre-amiral Pierre César Charles de Sercey, but the squadron dispersed in 1798 and by the summer of 1799 Preneuse was the only significant French warship remaining in the region.

The battle was the culmination of a three-month raiding cruise by the 40-gun French Navy frigate Preneuse, commanded by Captain Jean-Marthe-Adrien l'Hermite. Ordered to raid British commerce in the Mozambique Channel, l'Hermite's cruise had been eventful, with an inconclusive encounter with a squadron of small British warships in Algoa Bay on 20 September and an engagement with the 50-gun HMS Jupiter during heavy weather on 9–11 October.

Returning to Île de France in December, l'Hermite steered for Port Louis but was intercepted by the British blockade squadron, comprising the 74-gun ship of the line HMS Tremendous under John Osborn and the 50-gun HMS Adamant under William Hotham. Unable to reach safety, l'Hermite evaded pursuit long enough to drive Preneuse onto a beach at the mouth of the Tombeau. After a brief exchange of fire the wrecked frigate was surrendered and British boarding parties in ship's boats rowed inshore to Preneuse, removed the survivors and burnt the remains. Watching from the shore as the last of his command burned on the beach, Sercey subsequently retired from military service.

In 1796 British Royal Navy dominance in the East Indies during the French Revolutionary Wars was challenged by the arrival of a squadron of six French Navy frigates, commanded by Contre-amiral Pierre César Charles de Sercey. Among these ships was the new 40-gun frigate Preneuse, commanded by Captain Jean-Marthe-Adrien l'Hermite. Preneuse had not sailed from France with Sercey, instead passing independently through the Atlantic and uniting with the squadron at Port Louis on Île de France. Sercey deployed his squadron to the Dutch East Indies, but suffered frustration at the action of 9 September 1796 and the Bali Strait Incident of January 1797 and subsequently returned to the base at Port Louis. There the squadron began to fracture, with a succession of ships sent back to France or detached on independent missions.

Preneuse separated in March 1798, carrying messages of support and 86 military volunteers for the Tipu Sultan of the Kingdom of Mysore, an enemy of the British in Southern India who sought to form an alliance with France. L'Hermite's instructions emphasised subtlety in the operation, but on 20 April he attacked the British port of Tellicherry and seized the East Indiaman merchant ships Woodcot and Raymond. This alerted the British to Preneuse's mission and although the reinforcements were landed safely at Mangalore on 24 April, diplomatic relations between the British and Mysore collapsed, leading to the Fourth Anglo-Mysore War the following year in which Tipu Sultan was killed and his kingdom absorbed into British India.

L'Hermite then sailed to rejoin Sercey and the corvette Brûle-Gueule at Batavia in the Dutch East Indies for a planned junction with an allied Spanish squadron at Manila. This combined force then attacked an East India Company convoy gathering in the Pearl River in January 1799, but in the ensuing Macau Incident they were driven off by the Royal Navy escort squadron. Dispirited, Sercey returned westwards to Île de France, narrowly avoiding an unequal battle with a large British squadron blockading the port. On arrival he discovered that Preneuse and Brûle-Gueule were the only ships remaining of his original command, the others having returned to France or been lost in battle.

In September 1799 Sercey dispersed his remaining ships. Brûle-Gueule was sent back to France on 26 September carrying condemned political prisoners; the corvette was eventually wrecked on the Pointe du Raz with heavy loss of life. Preneuse was ordered to operate against British trade off the coast of Southeast Africa, sailing from Port Louis on 4 August. L'Hermite focused his efforts on the Mozambique Channel and the approaches to the British Cape Colony and on 20 September encountered a squadron anchored in Algoa Bay comprising the 24-gun naval storeship HMS Camel, the 16-gun HMS Rattlesnake (1791) and the schooner Surprise, the former ships lying with their masts and rigging removed. This force was supporting an expeditionary army under General Francis Dundas fighting the Third Xhosa War. Camel was laden with military supplies but neither ship was prepared for battle, with a 30 of Camel's sailors and 15 from Rattlesnake trapped on shore by the surf.

L'Hermite approached the anchored ships at 18:00, flying false Danish colours, and anchored nearby. A ship's boat from Camel approached the new arrival, rapidly realising that Preneuse was a hostile frigate and returning to their ship. Lieutenant William Fothergill, the most senior officer with the convoy, fired warning shots close to the frigate, which l'Hermite ignored. Both British ships then prepared for action. At 20:30, Preneuse began to approach Rattlesnake and Fothergill opened fire immediately, joined by Camel. L'Hermite returned fire, focusing its broadside on Camel. By midnight Camel had taken several shot in the hull causing widespread flooding, and the crew ceased firing to man the pumps. L'Hermite apparently believed that Camel had abandoned the fight and he switched fire towards Rattlesnake, the engagement continuing until 03:30 at which point l'Hermite slipped his anchor and pulled out of range. Remaining in the bay until 10:00 before standing out to sea. British losses were two killed and twelve wounded, both Camel and Rattlesnake badly damaged. It was later reported in French sources that l'Hermite believed the schooner Surprise to be a well armed naval brig, prompting his withdrawal. Preneuse's loss in the action was around 40 killed and wounded, and the frigate was reported to be badly damaged; messages to this effect were hastily sent to the commander at the Cape, Captain George Losack who sent the 50-gun HMS Jupiter in pursuit.