Battle of La Rochelle The naval Battle of La Rochelle took place on 22 and 23 June 1372 between a Castilian and French fleet commanded by the Genoese born Ambrosio Boccanegra and an English convoy commanded by John Hastings , 2nd Earl of Pembroke . The Franco - Castilian fleet had been sent to attack the English at La Rochelle , which was being besieged by French forces . Besides Boccanegra , other Castilian commanders were Cabeza de Vaca , Fernando de Peón and Ruy Díaz de Rojas . Pembroke had been dispatched to the town with a small retinue of 160 soldiers and instructions of recruit an army of 3 , 000 soldiers around Aquitaine . < ref name = " Sherborne / Tuck41 " > < / ref > From 22 to 23 June both fleets clashed . The strength of the Castilian fleet was estimated between the 12 galleys given by the Castilian chronicler and naval captain López de Ayala and the 40 sailing ships and 13 barges mentioned by the French chronicler Jean Froissart , while the English convoy would probably consist of 20 vessels , of which just 3 were escort warships of towers and the other 17 are believed to be small barges of about 50 tons . Thanks to their clear superiority both in ships and fighting men , the Castilians decisively defeated the English . Differing accounts from different historians exist about what actually transpired during the battle . These conflicts are mostly the work of nationalities ; English , Castilian , and French historians described the battle in varying ways , emphasizing certain aspects but marginalizing others . Nevertheless , the victory was complete and the whole English convoy was destroyed . In his return to the Iberian Peninsula , Boccanegra captured four additional English ships . Background . In 1372 the English monarch Edward III planned an important campaign in Aquitaine under the newly appointed lieutenant of the Duchy , the Earl of Pembroke . < ref name = " Sherborne / Tuck16 " > < / ref > He contracted to serve a year in the duchy with a retinue of 24 knights 55 squires and 80 archers besides another companies led by Sir Hugh Calveley and Sir John Devereux , who finally did not serve or did not appeared . < ref name = " Sherborne / Tuck17 " > < / ref > Pembroke received instructions of , on his arrival at France , recruit a host of 500 knight , 1 , 500 squires and 1 , 500 archers . One of Edward ' s clerks , John Wilton , was appointed to accompany the Earl with a large amount of money to pay the troops . The Earl of Pembroke , his retinue and Wilton embarked at Plymouth aboard a transport fleet which was unprepared for a serious engagement . The Castilian chronicler Pero López de Ayala estimated that this fleet had 36 ships , a number similar to that was said by the chronicler of the French court , 35 . Jean Froissart , in one of his two descriptions of the battle , put the English force on ' perpahs ' 14 ships . A fleet of 20 vessels is considered a creditable force . As most of them were small transports , Sir Philip Courtenay , the Admiral of the West , was detached to escort them with 3 ships with large tonnage and towers useful to archers . The English rule in Aquitaine was by then precarious . Since 1370 large parts of the region had fell under French rule and in 1372 Bertrand du Guesclin put the town of La Rochelle under siege . To respond to the demands of the Franco - Castilian alliance of 1368 , the king of Castile , Henry II of Trastámara , dispatched to Aquitaine a fleet under Ambrosio Boccanegra , who was seconded by Cabeza de Vaca , Fernando de Peón and Rui Díaz de Rojas . The size of this fleet is also subject of doubts . According to López de Ayala , is was composed of 12 galley s . Froissart , in his first relation , mentioned 40 sailing ships and 13 barges , but later reduced this numbers to 13 galleys . " Quatre Premiers Valois " and " Chronique des Pays - Bas " mention respectively 20 and 22 galleys . Battle . On 22 June the English convoy arrived at La Rochelle and the battle began as Pembroke ' s ships approached the harbour . This lay at the head of an inlet which was partially unnavigable at low water . The first Castilian attacks met a decided resistance . The English , despite the inferiority of their numbers , defended themselves well . At dusk , when the tide rose , the two fleets separated . Though they had lost two or four vessels , according to Froissart , the English were undefeated . Pembroke then withdrew some way from land , while Boccanegra anchored in front of La Rochelle . The Chronicle " Quatre Premiers Valois " , unlike López de Ayala and Froissart , implies that only some skirmishes took place on the first day , as Boccanegra would have ordered his galleys to withdraw , reserving them for the main action , what english understand like coward . According to this chronicle , the anchoring sites were reversed : the English off the town and the Castilians on the open sea . Froissart described a discussion between Pembroke and his men during the night of 22 – 23 June regarding how to escape the trap . An attempt to escape under the cover of the night was dismissed due to the fear of the Castilian galleys , as well as another to enter La Rochelle because of the low draft of the passage . In the end , the low tide left the English ships aground . When the fight resumed on the morning of the 23rd , the Castilians managed to set fire to some of them by spraying oil on their decks and rigging and then igniting it with flaming arrows . Many of the English were killed or burned alive , while other surrendered , among them Pembroke . The Castilian naval historian Cesáreo Fernández Duro claims that the English prisoners amounted to 400 knights and 8 , 000 soldiers , without counting the killed . Sherborne and Tuck say that the estimations recorded in the English chronicles that mention the battle speak of about 1 , 500 casualties , 800 deaths and between 160 and 400 prisoners . The whole fleet was destroyed or captured and £12 , 000 fell into Castilian hands . The defeat had been inevitable in view of the inequality between the fleets , beeing English fleet bigger than Castilian . By making prisoners , Admiral of Castile had with the vanquished in this battle a humanitarian gesture unusual in those days , it was customary then beheaded or throwing water all opponents , even if they had surrendered . Pembroke and seventy horsemen " of golden spurs " 2 were dispatched to Burgos , to the presence of King Henry , who presented the Constable Bertrand du Guesclin French hostage Earl , who died later in captivity . Aftermath . That suffered off La Rochelle was the first important English naval defeat of the Hundred Years ' War . Its effect upon the course of the war was significant : the loss of the town of La Rochelle on 7 September , which was followed during the second half of the year by nearly all of Poitou , Angoumois and Saintonge , which Bertrand du Guesclin cleared of English garrisons . Some authors claim that the battle cost England its naval supremacy along the French coast , < ref name = " Villalon / KaganXXXVI " > < / ref > but others disagree , though asserting that England ' s naval policy had become misguided . < ref name = " Sherborne / Tuck50 " > < / ref > On the one hand the projected resources to support John of Gaunt ' s claims to the Castilian throne were largely suspended , and on the other a great expedition under Edward III himself had to be suspended because of contrary winds . A year later after the battle , the English fleet had been rebuilt thanks to the works endured in fourteen differents towns . < ref name = " Sherborne / Tuck49 " > < / ref > On April 1373 a powerful force under William , Earl of Salisbury , with Admirals Neville and Courtenay and divided on two divisions ; the first consisting of 15 ships and 9 barges and the second 12 ships and 9 barges , in all 44 fighting vessels , set sail towards Portugal . Other ships and barges joined the large concentrarion and , by July , Salisbury had 56 ships crewed by 2 , 500 sailors and an army of 2 , 600 soldiers . The 1373 campaign was successful , seeing , amongst other , events , the burning of a Castilian merchant convoy at Saint - Malo .