Battle of Pontvallain The Battle of Pontvallain was an important battle in France ’ s Hundred Years War with England . It was fought the 4 December 1370 in the Sarthe region between English forces that had broken away from the army commanded by the English knight Sir Robert Knolles and a French army under the newly appointed Constable of France , Bertrand du Guesclin . The battle was in fact two separate engagements , one at Pontvallain and a smaller one at the nearby town of Vaas ; they are sometimes named as separate battles . Though the engagements were comparatively small - scale , they were significant because the English were routed , bringing to an end their 30 - year reputation for invincibility in open battle . Background . Robert Knolles landed at Calais in August 1370 with an army of about 6 , 000 mounted men and undertook a campaign in the style of a plundering raid through northern France . He approached Paris on 24 September and tried to draw out the French to battle , but they did not take the bait and by October Knolles had moved south and was marching towards Vendôme . He captured and garrisoned castles and monasteries between the rivers Loir and Loire and positioned himself to be able to march into Poitou or alternatively into southern Normandy if his King , Edward III , concluded an agreement with Charles II of Navarre , who was offering his lands in Northern Normandy as a base for the English . Many of the subordinate captains , who considered themselves better - born than Knolles , deplored his apparent lack of martial spirit . They found a leader in Sir John Minsterworth , an ambitious and unstable knight from the Welsh Marches who mocked Knolles as ‘ the old freebooter ’ . Meanwhile Charles V of France had invested his best knight , Bertrand du Guesclin , with the office of Constable of France , and tasked him with the mission of destroying Knolles ’ s army . In November du Guesclin concentrated his forces at Caen where he was joined by reinforcements under the Marshals Mouton de Blainville and Arnoul d ' Audrehem as well as a Breton contingent under Olivier de Clisson . He was thus able to raise about 4 , 000 men . A second army of about 1 , 200 men was formed in Knolles ’ s rear at Châtellerault under Marshal Sancerre , which then moved towards Knolles from the East while Du Guesclin began to move on him from the north . Knolles , aware that the French were closing in , now proposed to withdraw westward into Brittany before he could be surrounded , but his captains violently disagreed , preferring to find winter quarters where they were and to continue to raid the surrounding countryside , confident they could defeat any French attack . As a result the army divided ; Knolles took a contingent including his own retinue west towards Brittany . The remainder , numbering about 4 , 000 men , stayed in the region of the Loire valley in three groupings , one commanded jointly by Sir Thomas Grandison and Sir Hugh Calveley , the other two by Walter , Lord Fitzwalter and by Minsterworth . The Battle and Aftermath . Du Guesclin left Caen with his army on 1 December and marched south at great speed , arriving near Le Mans on 3 December . He received intelligence that Grandison ’ s and Fitzwalter ’ s forces were spread out in encampments between Pontvallain and Mayet and , despite his army ’ s exhaustion , ordered an immediate night march , arriving at Pontvallain to attack the English at dawn on 4 December . Taken completely by surprise , Grandison tried to retreat northwards but the French caught up with him beneath the walls of the Château de la Faigne . In a bitter hand - to - hand fight the French took heavy casualties ( Arnoul d ’ Audrehem later died of his wounds ) but Grandison ’ s forces were virtually wiped out and he was taken prisoner . The English archers , who had been the architects of victory in every previous battle with the French , were badly positioned but even so failed to penetrate the armour of du Guesclin ’ s troops or to break up the French lines . Meanwhile Sancerre was approaching Fitzwalter ’ s contingent from the east . The English fled south to the fortified abbey at Vaas , which was immediately assaulted by Sancerre and , when du Guesclin came up to support him , the English were massacred . Du Guesclin claimed Fitzwalter as his prisoner ( it was said he thought Fitzwalter was the Marshal of England ) . He was held prisoner until he was able to raise a ransom by mortgaging his Cumberland estates on ruinous terms to Edward III ' s mistress Alice Perrers . Sir John Minsterworth ’ s corps managed to escape into Brittany following Knolles , who was pursued unsuccessfully by Olivier de Clisson . Sir Hugh Calveley escaped into Poitou . About 300 English survivors , plus the garrisons of various castles Knolles had occupied , fled south towards Bordeaux but they were pursued by du Guesclin and Sancerre and , shortly after they had crossed the Loire , were caught and virtually wiped out beneath the walls of the castle of Bressuire , which though held for the English would not open its gates to them . Knolles and Minsterworth passed the winter in Brittany and then attempted to lead their companies to the port of Saint - Mathieu to take ship for England , but they were harried all the way by Olivier de Clisson and there were only two ships to take them , so most of their men were left on the shore to be massacred by the French . In England Minsterworth accused Knolles of responsibility for the disaster . In July 1372 the King ' s Council decided the main fault lay with Knolles , who was stripped of the lands he had been given as fee for organizing the campaign . Minsterworth was arrested and charged with traducing Knolles , but escaped and fled to France , where he changed sides and entered the service of Charles V .