Battle of Saint - Louis - du - Sud The Battle of Saint - Louis - du - Sud or the Battle of Port Louis was a battle fought in the Austrian War of Succession on 22 March 1748 in the French Caribbean colony of Saint Domingue . A British squadron under the command of Admiral Charles Knowles attacked and destroyed a large French fort under command of French governor Étienne Cochard de Chastenoye . Background . Britain had been attacking the Spanish colonies in the war of Jenkins Ear since 1739 but with only limited success . The War of Austrian Succession had spread to the Caribbean and French colonies soon became a target also and islands such as Guadeloupe , Martinique and Saint Domingue were under a close blockade by the Royal Navy . After Knowles finished his stint as governor of Louisbourg he was promoted to rear - admiral of the white on 15 July 1747 , and appointed as commander in chief on the Jamaica station . Knowles had initially intended to take his squadron and attack the Spanish at Santiago de Cuba , but contrary winds led to him deciding instead to attack Fort Saint Louis de Sud . Shortly before midday on 22 March 1748 in HMS " Elizabeth " Knowles ’ s led his squadron into the Saint - Domingue harbor of Port Saint Louis , completely surprising its defenders . An imposing seventy eight gun island castle guarded the road stead , manned by 310 troops and a company of black gunners under Governor Étienne Cochard de Chastenoye behind a twenty four foot - high stone walls . Battle . The ﬁrst French guns opened ﬁre at 12 : 05 pm but Knowles ’ s ships remained silent until all of them had anchored beneath the ramparts . As soon as this strategy was coming to form Knowles ordered his ships to open fire in a volley of broadsides at point blank range . A heated exchange ensued for the next three hours ; the British ships pounding the French fort . The desperate defenders sent a ﬁre - ship down from the inner roads , which compelled " Elizabeth " to cut her cable and warp out of danger . The remaining Royal Navy ships however maintained a ﬁerce pressure , so much so that the fort was starting to crumble and French counter fire was becoming slacker . Many guns and gun crews had been knocked out by British cannon fire and French casualties were heavy . Seeing the destruction that lay before him and British cannon fire not letting up , Chastenoye had no choice but to send out an officer out at 3 : 00 pm to suggest terms . Knowles made a counteroffer , and half an hour later the French commander accepted . The terms for the French were to surrender and that the fort would be occupied by the British without molestation . Aftermath . The garrison had suffered 160 casualties in all , compared to nineteen killed and fifty wounded among the British warships . The French garrison under the terms surrendered , but were soon released and marched away to the safety of the nearest settlement but keeping their firearms and not to fight against any of the British forces for a year and a day . British sailors and marines then occupied the fort and set about dismantling it . Over the course of the week the castle was set for demolition and destroyed . Knowles stood away on 30 March and knowing with victory complete , then headed off again hoping to assault Santiago de Cuba . This time however he was repelled by the Spanish . Ships involved . The British order of battle as reported by Schomberg :