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 . Background . During the early nineteenth century , the Indian Ocean formed an essential part of the network of trade routes that connected the British Empire . Heavily laden East Indiamen travelled from British Indian port cities such as Bombay or Calcutta to the United Kingdom carrying millions of pounds worth of goods . From Britain , the ships returned on the same routes , often carrying soldiers for the growing British Indian Army , then under the control of the Honourable East India Company ( HEIC ) . Following the outbreak of the Napoleonic Wars in 1803 , the British Admiralty had made the security of these routes a priority , and by 1807 the Dutch bases at the Cape of Good Hope and Java had been neutralised by expeditionary forces to prevent their use by enemy raiders . The French Indian Ocean possessions however , principally Île Bonaparte and Isle de France , were a more complicated target , protected from attack not only by the great distances involved in preparing an invasion attempt but also by heavy fortifications and a substantial garrison of French Army soldiers augmented by a large local militia . The French had recognised the importance of these islands as bases for raiding warships during the French Revolutionary Wars ( 1793 – 1801 ) , but by late 1807 the only naval resources allocated to the region were a few older frigates and a large number of local privateers . Following the reduction of these remaining naval forces on Isle de France during 1808 , by defeat in battle and disarmaments due to age and unseaworthiness , the French naval authorities made a serious attempt to disrupt British trade in the region , ordering five large modern frigates to sail to Isle de France under Commodore Jacques Hamelin . Four of these ships broke through the British blockade of the French coast , arriving in the Indian Ocean in the spring of 1809 , where Hamelin dispersed them into the Bay of Bengal with orders to intercept , attack and capture or destroy the heavily armed but extremely valuable convoys of East Indiamen . The first French success came at the end of the spring , when the frigate " Caroline " successfully attacked a convoy at the Action of 31 May 1809 , seizing two heavily laden merchant ships . Commodore Josias Rowley was given command of the British response to the French deployment , a hastily assembled force composed mainly of those ships available at the Cape of Good Hope in early 1809 . Ordered to stop the French raiders , Rowley was unable to spread his limited squadron wide enough to pursue the roving French frigates , instead using his forces to blockade and raid the French Indian Ocean islands in anticipation of Hamelin ' s return . In August 1809 , " Caroline " arrived with her prizes at Saint Paul on Île Bonaparte and Rowley determined to seize the frigate . He planned a successful invasion of the town , launched on 20 September 1809 , which resulted in the capture of the port ' s defences , " Caroline " and the captured East Indiamen . With his objectives complete , Rowley withdrew five days later . Almost a year later , Rowley returned with a larger task force and made a second landing around the capital of Île Bonaparte , Saint Denis . Marching on the seat of government , Rowley ' s troops rapidly overwhelmed the defences and forced the island ' s garrison to surrender , renaming the island Île Bourbon and installing a British governor . Hamelin had used the British preoccupation with Île Bonaparte to send additional frigates to sea during 1809 and early 1810 , including his flagship " Vénus " , which captured three East Indiamen at the Action of 18 November 1809 , and " Bellone " , which took the Portuguese frigate " Minerva " in the Bay of Bengal a few days later . " Minerva " , renamed " Minerve " in French hands , was subsequently involved in the Action of 3 July 1810 , when a further two East Indiamen were captured . The squadron in the latter action was commanded by Guy - Victor Duperré in " Bellone " , whose ships were so badly damaged that Duperré was forced to spend nearly a month repairing his vessels in the Comoros Islands before they were ready to return to Isle de France . Operations off Grand Port . With Île Bourbon secured in July 1810 , the British now occupied a large fortified island base within easy sailing distance of Isle de France . Even before Île Bourbon was completely in British hands , Rowley had detached HMS " Sirius " from the invasion squadron with orders to restore the blockade of Isle de France . Shortly afterwards , " Sirius " < nowiki > ' < / nowiki > s captain Samuel Pym led his men in a raid on a coastal vessel moored off the southern side of the island . Two days after this successful operation , reinforcements arrived in the form of the frigates HMS " Iphigenia " , HMS " Nereide " and the small brig HMS " Staunch " . " Nereide " carried 100 specially selected soldiers from the 69th and 33rd Regiments and some artillerymen from the garrison at Madras , to be used in storming and garrisoning offshore islands , beginning with Île de la Passe off Grand Port , a well defended islet that protected a natural harbour on the southeastern shore . These fortified islands could be used to block entry to the ports of Isle de France and thus trap Hamelin ' s squadron . Grand Port was an easily defensible natural harbour because the bay was protected from the open sea by a large coral reef through which a complicated channel meandered , known only to experienced local pilots . Île de la Passe was vitally important in the control of Grand Port because it featured a heavy battery that covered the entrance to the channel , thus controlling the passage to the sheltered inner lagoon . The British planned to use the troops on " Nereide " , under her captain Nesbit Willoughby , to storm Île de la Passe and capture the battery . Willoughby would then use a local man serving on his ship named John Johnson ( known in some texts as " the black pilot " ) , to steer through the channel and land troops near the town , distributing leaflets promising freedom and prosperity under British rule in an attempt to corrode the morale of the defenders . The first attack on Île de la Passe was launched on the evening of 10 August , with " Staunch " towing boats carrying over 400 soldiers , Royal Marines and volunteer sailors to the island under cover of darkness , guided by " Nereide " < nowiki > ' < / nowiki > s pilot . During the night however , the pilot became lost and the boats were scattered in high winds and had not reassembled by dawn . To distract French attention from the drifting boats , Pym directed Captain Henry Lambert in " Iphigenia " to sail conspicuously off Port Napoleon , where the main body of the French squadron , led by Hamelin in " Vénus " , was based . Pym joined Lambert later in the day and the frigates subsequently returned to the waters of Grand Port by different routes , confusing French observers from the shore as to British intentions . By 13 August , the boats originally intended for the attack had still not been assembled and Pym decided that he could not risk waiting any longer without the French launching a counterattack . Launching his own boats at 20 : 00 ( local time ) , guided by the pilot and commanded by Pym ' s second in command , Lieutenant Norman , Pym ' s marines and sailors landed on the island in darkness under heavy fire from the defenders . Norman was killed in the initial exchange of fire , but his deputy Lieutenant Watling seized the island by storming the fortifications surrounding the battery . Seven British personnel were killed and 18 wounded in the battle , in which the storming party managed to seize intact French naval code books and took 80 prisoners . Willoughby was furious that Pym had assumed command of the operation without his permission and the officers exchanged angry letters , part of an ongoing disagreement between them that engendered mutual distrust . With Île de la Passe secure , Pym gave command of the blockade of Grand Port to Willoughby and returned to his station off Port Napoleon with " Iphigenia " . Willoughby used his independent position to raid the coastline , landing at Pointe du Diable on 17 August on the northern edge of Grand Port with 170 men and storming the fort there , destroying ten cannon s and capturing another . Marching south towards the town of Grand Port itself , Willoughby ' s men fought off French counterattacks and distributed propaganda pamphlets at the farms and villages they passed . Willoughby re - embarked his troops in the evening but landed again the following day at Grande Rivière to observe the effects of his efforts . Burning a signal station , Willoughby advanced inland , but was checked by the arrival of 800 French reinforcements from Port Napoleon and returned to HMS " Nereide " . The brief expedition cost the British two men wounded and one missing , to French casualties of at least ten killed or wounded . Willoughby followed the attack on Grande Rivière with unopposed minor landings on 19 and 20 August . Duperré ' s arrival . Willoughby ' s raiding was interrupted at 10 : 00 on 20 August when five ships were sighted , rapidly approaching from the southeast . These ships were Guy - Victor Duperré ' s squadron of " Bellone " , " Minerve " , corvette " Victor " and prizes " Windham " and " Ceylon " returning from the Comoros Islands . Following a month of repairs on Anjouan , Duperré had sailed for Isle de France without encountering any opposition on his return passage , and was intending to enter Grand Port via the channel protected by Île de la Passe . Duperré was unaware of the British occupation of the island , and Willoughby intended to lure the French squadron into the channel by concealing the British presence off the harbour . Once there , Willoughby hoped to defeat them or damage them so severely that they would be unable to break out unaided , thus isolating Duperré ' s squadron from Hamelin ' s force in Port Napoleon and containing the French in separate harbours to prevent them from concentrating against the British blockade squadrons . Willoughby brought " Nereide " close to Île de la Passe to combine their fire and protect his boats , which were carrying 160 men back to " Nereide " from a raid near Grand Port that morning . Raising a French tricolour over Île de la Passe and on " Nereide " , Willoughby transmitted the French code captured on the island : " " L ' ennemi croise au Coin de Mire " " and received an acknowledgement from Duperré . The use of these signals convinced Duperré , over the objections of Captain Pierre Bouvet on " Minerve " , that " Nereide " was Surcouf ' s privateer " Charles " , which was expected from France . The French squadron closed with the harbour during the morning , " Victor " entering the channel under Île de la Passe at 13 : 40 . As " Victor " passed " Nereide " and the fort Willoughby opened fire , Lieutenant Nicolas Morice surrendering the outnumbered corvette after the first volley . Willoughby sent boats to attempt to take possession of " Victor " , but they were unable to reach the vessel . Behind the corvette , " Minerve " and " Ceylon " pushed into the channel and signalled Morice to follow them , exchanging fire with the fort . As Morice raised his colours again and followed " Minerve " , a large explosion boiled out of Île de la Passe , where the false French flag had ignited on a brazier as it was lowered and set fire to a nearby stack of cartridges , which exploded in the close confines of the fort . Three men were killed and 12 badly burned , six cannons were dismounted and one discharged unexpectedly , killing a British sailor in a boat attempting to board " Victor " . With the fort out of action and a significant number of her crew scattered in small boats in the channel , " Nereide " alone was unable to block French entry to Grand Port . With Willoughby ' s ambush plan ruined , the scattered boats sought to rejoin " Nereide " , passing directly through the French squadron . Although several boats were in danger of being run down by the French ships and one even bumped alongside " Minerve " , all eventually rejoined " Nereide " safely . However , the opportunity to cause significant damage to the French in the narrow channel had been lost , " Bellone " joining the squadron in passing through the channel with minimal resistance . In addition to British losses in the explosion at the fort , two men had been killed and one wounded on " Nereide " . French losses were more severe , " Minerve " suffering 23 casualties and " Ceylon " eight . With both sides recognising that further action was inevitable , Willoughby sent a boat to " Sirius " requesting additional assistance and Duperré sent a message overland with Lieutenant Morice , requesting support from Hamelin ' s squadron ( Morice fell from his horse during the mission and was very severely injured ) . Command of " Victor " passed to Henri Moisson . In the afternoon , Willoughby used mortars on Île de la Passe to shell the French squadron , forcing Duperré to retreat into the shallow harbour at Grand Port and Willoughby subsequently sent officers into Grand Port on 21 August under a flag of truce , demanding the release of " Victor " , which he insisted had surrendered and should thus be handed over to the blockade squadron as a prize . Duperré refused to consider the request . One French ship had failed to enter the channel off Grand Port : the captured East Indiaman " Windham " . Early on 21 August , her French commander attempted to shelter in Rivière Noire . " Sirius " spotted the merchant ship under the batteries there and sent two boats into the anchorage , stormed the ship and brought her out without a single casualty . This success was remarkable as the boarding party had forgotten to take any weapons with them and were only armed with wooden foot - stretchers wielded as clubs . Battle . From prisoners captured on " Windham " , Pym learned of the nature and situation of Duperré ' s squadron and sent orders to Port Napoleon with Captain Lucius Curtis in the recently arrived HMS " Magicienne " for " Iphigenia " to join " Sirius " and " Nereide " off Grand Port . " Sirius " and " Nereide " met on the morning of 22 August , Willoughby welcoming Pym with signals describing an " enemy of inferior force " . Although Duperré ' s squadron was technically weaker than the four British frigates combined , Willoughby ' s signal was misleading as the French had taken up a strong crescent shaped battleline in the bay and could cover the mouth of the channel through which the British ships could only pass one at a time . Duperré also anticipated the arrival of reinforcements from Port Napoleon under Governor Charles Decaen at any time and could call on the support of soldiers and gun batteries on shore . In addition , French launches had moved the buoys marking the channel through the coral reef to confuse any British advance . British attack . On 22 August at 14 : 40 , Pym led an attack on Duperré ' s squadron without waiting for " Iphigenia " and " Magicienne " , entering the channel that led to the anchorage at Grand Port . He was followed by " Nereide " , but Willoughby had refused to allow Pym to embark the harbour pilot : the only person in the British squadron who knew the passage through the reefs . Without guidance by an experienced pilot , " Sirius " was aground within minutes and could not be brought off until 08 : 30 on the 23 August . " Nereide " anchored nearby during the night to protect the flagship . At 10 : 00 , " Iphigenia " and " Magicienne " arrived and at 14 : 40 , after a conference between the captains as to the best course of action , the force again attempted to negotiate the channel . Although the squadron was now guided by " Nereide " < nowiki > ' < / nowiki > s pilot , " Sirius " again grounded at 15 : 00 and " Magicienne " 15 minutes later after over - correcting to avoid the reef that " Sirius " had struck . " Nereide " and " Iphigenia " continued the attack , " Iphigenia " engaging " Minerve " and " Ceylon " at close range and " Nereide " attacking " Bellone " . Long - range fire from " Magicienne " was also directed at " Victor " , which was firing on " Nereide " . Within minutes of the British attack , " Ceylon " surrendered and boats from " Magicienne " sought but failed to take possession of her . The French crew drove the captured East Indiaman on shore , joined shortly afterwards by " Minerve " , " Bellone " and later by " Victor " , so that by 18 : 30 the entire French force was grounded and all but " Bellone " prevented from firing their main broadsides by beached ships blocking their arc of fire . " Bellone " however was ideally positioned to maintain her fire on " Nereide " from her beached position , and at 19 : 00 a cannon shot cut " Nereide " < nowiki > ' < / nowiki > s stern anchor cable . The British frigate swung around , presenting her stern to " Bellone " and pulling both her broadsides away from the French squadron . Raked by " Bellone " and desperate to return fire , Willoughby had the bow anchor cable cut , bringing a portion of his ship ' s starboard broadside to bear on " Bellone " . At 20 : 00 , Duperré was seriously wounded in the cheek by shrapnel from a grape shot fired by " Nereide " ; Ensign Vigoureux concealed his unconscious body under a signal flag and discreetly brought him below decks while Bouvet assumed command of the French squadron on board " Bellone " , placing Lieutenant Albin Roussin in charge of " Minerve " . Building an improvised bridge between the French ships and the shore , Bouvet increased the men and ammunition reaching " Bellone " and thus significantly increased her rate of fire . He also had the rail removed between the foredeck and the quarterdeck of " Minerve " , and had iron hooks nailed to the freeboard below the starboard gangway as to provide atachement points for additional guns , thus building a continuous second deck on his frigate where he constituted a complete second battery . By 22 : 00 " Nereide " was a wreck , receiving shot from several sides , with most of her guns dismounted and casualties mounting to over 200 : the first lieutenant was dying , the second was severely wounded and Willoughby ' s left eye had been dislodged from its socket by a wooden splinter . Recognising her battered state , Bouvet then diverted fire from " Nereide " to concentrate on " Magicienne " . Refusing to surrender until all options had been exhausted , Willoughby dispatched boats to " Sirius " , asking Pym if he believed it would be practical to send boats to tow " Nereide " out of range . Pym replied that with the boats engaged in attempting to tow " Sirius " and " Magicienne " off the reef it was not possible to deploy them under fire to tow " Nereide " . Pym also suggested that Willoughby disembark his men and set fire to his ship in the hope that the flames would spread to the French ships clustered on shore . Willoughby refused this suggestion as it was not practical to disembark the dozens of wounded men aboard " Nereide " in the growing darkness and refused to personally abandon his men when Pym ordered him to transfer to " Sirius " . At 23 : 00 , Willoughby ordered a boat to row to " Bellone " and notify the French commander that he had surrendered . However , Willoughby ' s boat had been holed by shot and was unable to make the short journey . The message was instead conveyed by French prisoners from " Nereide " who had dived over board and reached the shore during the night . Recalling the false flags used on 20 August , Bouvet resolved to wait until morning before accepting the surrender . Attempted withdrawal . At 01 : 50 on 24 August , " Bellone " ceased firing on the shattered " Nereide " . During the remaining hours of darkness , Pym continued his efforts to dislodge " Sirius " from the reef and sent orders to Lambert , whose " Iphigenia " had been blocked from firing on the French by " Nereide " and also prevented from pursuing the " Minerve " by a large reef blocking access to the beach . With " Iphigenia " now becalmed in the coastal waters , Pym instructed Lambert to begin warping his ship out of the harbour , using anchors attached to the capstan to drag the ship slowly through the shallow water . " Magicienne " , like " Iphigenia " , had been stranded out of range of the beached French ships and so had instead directed her fire against a battery erected on shore , which she had destroyed by 02 : 00 . When daylight rose , it showed a scene of great confusion , with " Sirius " and " Magicienne " grounded in the approaches to the harbour , the French ships " on shore in a heap " in the words of Captain Pym , " Iphigenia " slowly pulling herself away from the French squadron and " Nereide " lying broken and battered under the guns of " Bellone " , a Union Flag nailed to her masthead . This flag prompted a fresh burst of cannon fire from Bouvet , and it was not until Willoughby ordered the mizenmast to be chopped down that the French acknowledged the surrender and ceased firing . At 07 : 00 , Lambert notified Pym that he had cleared the reef separating " Iphigenia " from the French ships and suggested that if Pym sent reinforcements from " Sirius " he might be able to board and capture the entire French squadron . Pym refused permission , insisting that Lambert assist him in pulling " Sirius " off the reef instead . Although Lambert intended to subsequently attack the French alone , Pym forbade him and sent a direct order for Lambert to move out of range of the enemy . At 10 : 00 , " Iphigenia " reached " Sirius " and together the ships began firing at French troops ashore , who were endeavouring to raise a gun battery within range of the frigates . " Magicienne " , irretrievably stuck on the reef , rapidly flooding and with her capstan smashed by French shot , now bore the brunt of long - range French fire from both " Bellone " and the shore until Pym ordered Curtis to abandon his ship , transferring his men aboard " Iphigenia " . At 19 : 30 " Magicienne " was set on fire , her magazines exploding at 23 : 00 . On the shoreline , Duperré had been unable to spare any men to take possession of " Nereide " until 15 : 00 . A party under Lieutenant Roussin , second in command on " Victor " and temporarily in command of " Minerve " , was sent but had orders to return once the ship had been disarmed : freeing the remaining French prisoners , Roussin spiked the guns to prevent their further use , administered basic medical care and returned to shore , recounting that over 100 men lay dead or dying aboard the British frigate . At 04 : 00 on 25 August , the newly erected French gun battery opened fire on " Sirius " and " Iphigenia " , which returned fire as best they could . Accepting that " Sirius " was beyond repair , Pym removed all her personnel and military supplies , setting fire to the frigate at 09 : 00 , shortly after " Iphigenia " had pulled beyond the range of the battery , using a cannon as an anchor after losing hers the previous day . French boats attempted to reach " Sirius " and capture her before she exploded , although they turned back when Pym launched his own boats to contest possession of the wreck . The frigate ' s remaining munitions exploded at 11 : 00 . During the morning , Duperré sent an official boarding party aboard " Nereide " , who wet the decks to prevent any risk of fire from the ships burning in the harbour and removed 75 corpses from the frigate . French response . When news of the arrival of Duperré ' s squadron reached Decaen at Port Napoleon , he immediately despatched fast couriers to Grand Port and ordered Hamelin ' s squadron , consisting of the frigates " Vénus " , " Manche " , " Astrée " and the brig " Entreprenant " , to make ready to sail in support of Duperré . Hamelin departed Port Napoleon at midnight on 21 August , intending to sail northeast and then south , down the island ' s eastern shore . On 23 August , Hamelin ' s squadron spotted and captured a British transport ship named " Ranger " , sent 24 days earlier from the Cape of Good Hope with 300 tons of food supplies and extensive naval stores for Rowley on Île Bourbon . On rounding the northern headlands of Isle de France however , Hamelin found he could make no progress against the headwinds and reversed direction , passing the western shore of the island and arriving off Grand Port at 13 : 00 on 27 August . The two extra days Hamelin had spent rounding Isle de France saw activity from the British forces remaining at Grand Port . There had been no strong winds in the bay and " Iphigenia " was forced to resort to slowly warping towards the mouth of the channel in the hope of escaping the approaching French reinforcements . Boats had removed the crews of " Sirius " and " Magicienne " to Île de la Passe , where the fortifications had been strengthened , but supplies were running low and " Magicienne " < nowiki > ' < / nowiki > s launch was sent to Île Bourbon to request urgent reinforcement and resupply from Rowley ' s remaining squadron . On the morning of 27 August , Lambert discovered the brig " Entreprenant " off the harbour mouth and three French sail approaching in the distance . " Iphigenia " was still three quarters of a mile from Île de Passe at the edge of the lagoon and was low on shot and unable to manoeuvre in the calm weather without anchors . Recognising that resistance under such conditions against an overwhelming force was futile , Lambert negotiated with Hamelin , offering to surrender Île de la Passe if " Iphigenia " and the men on the island were given permission to sail to Île Bourbon unmolested . British surrender . On the morning of 28 August , Lambert received a message from Hamelin , promising to repatriate all the prisoners under conditions of parole within one month if Île de la Passe and " Iphigenia " were both surrendered without resistance . The message also threatened that if Lambert refused , the French would attack and overwhelm the badly outnumbered British force . Recognising that food supplies were low , reinforcements had not arrived and that his ammunition stores were almost empty , Lambert agreed to the terms . Lambert later received a message from Decaen proposing similar terms and notified the French governor that he had surrendered to Hamelin . Decaen was furious that Hamelin had agreed terms without consulting him , but eventually agreed to accept the terms of the surrender as well . The wounded were treated by French doctors at Grand Port and later repatriated , although the remainder of the prisoners were placed in a cramped and unpleasant prison at Port Napoleon from which , despite the terms of the surrender , they were not released until British forces captured the island in December . Rowley first learned of the operations off Grand Port on 22 August , when " Windham " arrived off Saint Paul . Eager to support Pym ' s attack , Rowley immediately set sail in his frigate HMS " Boadicea " , with the transport " Bombay " following with two companies of the 86th Regiment of Foot to provide a garrison on any territory seized in the operation . The headwinds were strong and it was not until 29 August that Rowley arrived off Grand Port , having been notified of the situation there by " Magicienne " < nowiki > ' < / nowiki > s launch the previous day . Sighting a cluster of frigates around Île de la Passe , Rowley closed with the island before turning sharply when " Vénus " and " Manche " raised their colours and gave chase . Rowley repeatedly feinted towards the French ships and then pulled away , hoping to draw them away from Grand Port in the hope that " Bombay " might board the now unprotected " Iphigenia " and capture her . " Bombay " was thwarted by the reappearance of " Astreé " and " Entreprenant " and Rowley was chased by " Vénus " and " Manche " back to Saint Denis , anchoring there on 30 August . Rowley attempted a second time to rescue " Iphigenia " from Grand Port the following week , but by the time he returned " Bellone " and " Minerve " had been refloated and the French force was far too strong for Rowley ' s flagship to attack alone . Aftermath . The battle is noted as the most significant defeat for the Royal Navy during the Napoleonic Wars . Not only had four frigates been lost with their entire crews , but 105 experienced sailors had been killed and 168 wounded in one of the bloodiest frigate encounters of the war . French losses were also heavy , with Duperré reporting 36 killed and 112 wounded on his squadron and among the soldiers firing from the shore . The loss of such a large proportion of his force placed Rowley at a significant disadvantage in September 1810 , as Hamelin ' s squadron , bolstered by the newly commissioned " Iphigénie " , now substantially outnumbered his own ( the ruined " Néréide " was also attached to the French squadron , but the damage suffered was so severe that the ship never sailed again ) . Withdrawing to Isle de France , Rowley requested that reinforcements be diverted from other duties in the region to replace his lost ships and to break the French blockade of Île Bourbon , led by Bouvet . These newly arrived British frigates , cruising alone in unfamiliar waters , became targets for Hamelin , who twice forced the surrender of single frigates , only for Rowley to beat his ships away from their prize each time . On the second occasion , Rowley was able to chase and capture Hamelin and his flagship " Vénus " , bringing an end to his raiding career and to the activities of his squadron , who remained on Isle de France until they were all captured at the fall of the island in December 1810 by an invasion fleet under Vice - Admiral Albemarle Bertie . In France the action was greeted with celebration , and it became the only naval battle commemorated on the Arc de Triomphe . The British response was despondent , although all four captains were subsequently cleared and praised at their courts - martial inquiring into the loss of their ships . The only criticism was of Willoughby , who was accused of giving a misleading signal in indicating that the French were of inferior force on 22 August . Contemporary historian William James described British reaction to the battle as " that the noble behaviour of her officers and crew threw such a halo of glory around the defeat at Grand Port , that , in public opinion at least , the loss of four frigates was scarcely considered a misfortune . " However , he also notes that " No case of which we are aware more deeply affects the character of the Royal Navy than the defeat it sustained at Grand Port . " The battle subsequently attracted the attention of authors from both Britain and France , featuring in the 1843 novel " Georges " by Alexandre Dumas , and the 1977 novel " The Mauritius Command " by Patrick O ' Brian . On 30 December 1899 , a monument was erected at the harbour of Grand Port in the memory of the British and French sailors who were killed in the engagement .