Battle of Grand Port

The Battle of Grand Port was a naval battle between squadrons of frigates from the French Navy and the British Royal Navy. The battle was fought during 20–27 August 1810 over possession of the harbour of Grand Port on Isle de France (now Mauritius) during the Napoleonic Wars. The British squadron of four frigates sought to blockade the port to prevent its use by the French through the capture of the fortified Île de la Passe at its entrance. This position was seized by a British landing party on 13 August, and when a French squadron under Captain Guy-Victor Duperré approached the bay nine days later the British commander, Captain Samuel Pym, decided to lure them into coastal waters where his superior numbers could be brought to bear against the French ships.

Four of the five French ships managed to break past the British blockade, taking shelter in the protected anchorage, which was only accessible through a series of complicated reefs and sandbanks that were impassable without an experienced harbour pilot. When Pym ordered his frigates to attack the anchored French on 22 and 23 August, his ships became trapped in the narrow channels of the bay: two were irretrievably grounded; a third, outnumbered by the combined French squadron, was defeated; and a fourth was unable to close to within effective gun range. Although the French ships were also badly damaged, the battle was a disaster for the British: one ship was captured after suffering irreparable damage, the grounded ships were set on fire to prevent their capture by French boarding parties and the remaining vessel was seized as it left the harbour by the main French squadron from Port Napoleon under Commodore Jacques Hamelin.

The British defeat was the worst the Royal Navy suffered during the entire war, and it left the Indian Ocean and its vital trade convoys exposed to attack from Hamelin's frigates. In response, the British authorities sought to reinforce the squadron on Île Bourbon under Josias Rowley by ordering all available ships to the region, but this piecemeal reinforcement resulted in a series of desperate actions as individual British ships were attacked by the more powerful and confident French squadron. It was not until December 1810 that an adequate reinforcement could be collected, with the provision of a strong battle squadron under Admiral Albemarle Bertie that rapidly invaded and subdued Isle de France.