Battle of Saint - Mathieu The naval Battle of Saint - Mathieu took place on 10 August 1512 during the War of the League of Cambrai , near Brest , France , between an English fleet of 25 ships commanded by Sir Edward Howard and a Franco - Breton fleet of 22 ships commanded by René de Clermont . It is possibly the first battle between ships using cannon through ports , although this played a minor role in the fighting . This was one of only two full - fledged naval battles fought by King Henry VIII ' s Navy Royal . During the battle , each navy ' s largest and most powerful ship — " Regent " and " Marie - la - Cordelière " ( or simply " Cordelière " ) — was destroyed by a large explosion aboard the latter . Background . Although the War of the League of Cambrai , sometimes known as the War of the Holy League ( among several alternative names ) was largely an Italian war , nearly every significant power in Western Europe participated at one point or another , including France , England , and Brittany . The latter was independent of France at the time , although the two were closely allied . When war with France broke out in April 1512 , England ' s Edward Howard was appointed Admiral of a fleet sent by King Henry VIII to control the sea between Brest and the Thames estuary . Howard seized vessels of various nationalities on the pretext that they were carrying French cargoes . At the beginning of June , he escorted to Brittany an army which Henry sent to France under the command of Thomas Grey , 2nd Marquess of Dorset with the hope of recovering Guyenne . Howard then raided Le Conquet and Crozon on the Breton coast . During June and July , Howard effectively controlled the English Channel and is said to have captured more than 60 vessels . By August , a French - Breton fleet had assembled at Brest ; Howard moved to attack them . Battle . Well informed about the Franco - Breton manoeuvres , the English surprised them at anchor . Unprepared and confronted by a superior fleet , all the French and Breton ships cut their anchor cables and spread their sails . By accident , about 300 guests , including some women , were visiting the Breton flagship " Marie la Cordelière " when it was attacked . In the hurry , Hervé de Portzmoguer , the captain of the ship , could not disembark them and the crew was thus reinforced by those " involuntary " combatants who , however , fought bravely . The two main ships ( " Marie la Cordelière " and " Petite Louise " ) faced the enemy to cover the retreat of the rest of the fleet to the port of Brest . Under English fire , " Marie la Cordelière " — with 1 , 000 Tons one of the largest in her time — sailed towards the " Regent " , with 600 Tons the largest and most powerful ship in the English navy . The " Sovereign " and the " Mary James " rushed to rescue the " Regent " and surrounded the " Cordelière " , while the superior fire of the " Mary Rose " badly damaged the " Petite Louise " which was forced to retreat . The " Cordelière " remained alone among the English fleet , with the exception of the small " Nef - de - Dieppe " which harassed the English ships . The " Cordelière " s cannons dismasted both " Sovereign " and " Mary James " which became ungovernable and drifted in the Iroise Sea . Hervé de Portzmoguer , also known as " Primauguet " , the Breton captain of the " Cordelière " ordered the assault of the " Regent " . Grappling hooks were thrown and the two ships were tied together . The seamen of the " Marie - la - Cordelière " rushed on the " Regent " ' s deck which was constantly being reinforced by English ships transferring their crews on the " Regent " . The little " Nef - de - Dieppe " manoeuvered skillfully to bombard these new assailants . The deck of the " Regent " was covered by blood when , suddenly , the " Cordelière " exploded . The flames spread to the " Regent " and both ships sank . The crews of both ships were almost entirely annihilated . Only 20 wounded Breton sailors out of 1 , 250 were saved from the " Cordelière " and 60 out of 460 English from the " Regent " . Howard was devastated by the death of Thomas Knyvet , commander of the " Regent " , and vowed " that he will never see the King in the face till he hath revenged the death of the noble and valiant knight , Sir Thomas Knyvet . " Over the next two days , with the French fleet in Brest , the English fleet captured or destroyed thirty - two French vessels and recovered the valuable French anchors before returning to England . As a result of the engagement Sir Edward Howard was made Lord High Admiral by . Role in Breton culture . Brittany and France were still technically separate realms at the time , united only dynastically through the marriage of Duchess Anne to king Louis XII of France . The combination of the French and Breton fleets was thus the first significant military action in which the two countries fought together , twenty four years after the Battle of Saint - Aubin - du - Cormier ( 1488 ) , the last battle between them . It thus became symbolic within Brittany of the unity between Brittany and France . The destruction of the Breton ship " Marie la Cordelière " quickly became famous . French poets Humbert de Montmoret and Germain de Brie both wrote poems about it . The latter work presented such an exaggeratedly heroic version of the death of Hervé de Portzmoguer , that it occasioned a satirical response from Thomas More , leading to a literary battle between More and de Brie . The death of de Portzmoguer , on the day of Saint Lawrence ( 10 August ) , was later portrayed as a deliberate act of self - sacrificing heroism . He is supposed to have said « Nous allons fêter saint Laurent qui périt par le feu ! » . ( " we will celebrate the feast of Saint Lawrence , who died by fire " ) before blowing up the ship to avoid its capture . In fact , there is no evidence that the explosion was intentional and early literary accounts make no such claims . This version was commemorated by the Breton poet Théodore Botrel . A similar version is portrayed by Alan Simon in the song " Marie la Cordelière " from " Anne de Bretagne " ( 2008 ) .