 Over the following year , the French continued to attack British trade convoys , achieving important victories at the Action of 18 November 1809 and the Action of 3 July 1810 , where they captured another five East Indiamen as well as numerous smaller merchant ships and a large Portuguese frigate . Rowley too was active , commanding the successful Invasion of Île Bonaparte in July and renaming the island Île Bourbon , basing his squadron at Saint Paul on the island 's eastern shore . From this base , Rowley 's ships were ideally positioned to begin a close blockade of Isle de France , led initially by Captain Samuel Pym in HMS Sirius . Pym sought to reduce French movement by seizing a number of fortified offshore islands , starting with Île de la <unk> off Grand Port . The island was captured , but when a French squadron broke through the British blockade and took shelter in Grand Port , Pym resolved to attack them . The ensuing Battle of Grand Port was a disaster for Rowley 's squadron , as Pym led four of Rowley 's five frigates into the bay without adequately assessing the channel through the coral reefs that sheltered the harbour . As a result , two frigates grounded out of range of the enemy and the remaining two were outnumbered in confined waters . In a complicated battle lasting several days , two of Pym 's frigates were captured and two more had to be scuttled , with their entire crews made prisoner . Rowley 's reinforcements arrived too late , and the British <unk> was chased back to Saint Denis by Hamelin 's flagship . 
