The Battle of Pontvallain, part of the Hundred Years' War, took place in the Sarthe region of north-west France on 4 December 1370, when a French army under Bertrand du Guesclin heavily defeated an English force which had broken away from an army commanded by Sir Robert Knolles. The French numbered 5,200 men, and the English force was approximately the same size.
The English had plundered and burnt their way across northern France from Calais to Paris. With winter coming, the English commanders fell out and divided their army into four. The battle consisted of two separate engagements: one at Pontvallain where, after a forced march, which continued overnight, Guesclin, the newly appointed constable of France, surprised a major part of the English force, and wiped it out. In a coordinated attack, Guesclin's subordinate, Louis de Sancerre, caught a smaller English force the same day, at the nearby town of Vaas, also wiping it out. The two are sometimes named as separate battles.
The French harried the surviving Englishmen into the following year, recapturing much lost territory. Though the engagements were comparatively small, they were significant because the English were routed, ending a reputation for invincibility in open battle they had enjoyed since the war started in 1337.
Background
Following a series of disagreements between Philip VI of France () and Edward III of England (), on 24 May 1337 Philip's Great Council in Paris agreed that the lands held by Edward in France should be taken back into Philip's hands on the grounds that Edward was in breach of his obligations as a vassal. This marked the start of the Hundred Years' War, which was to last 116 years. In 1340 Edward claimed the French Crown, proclaiming himself the rightful heir through his mother, Isabella of France.
The English campaigned frequently on the continent, gaining a long run of military successes against larger forces across France. In 1356 a large French army was decisively defeated at the Battle of Poitiers, in which King John II of France (), the son and successor of King Philip, was captured. This eventually led to peace being agreed, and the Treaty of Brétigny was signed in 1360. It ceded large parts of south-west France to England as its sovereign territory, while Edward renounced all claims to the French throne. The terms of Brétigny were meant to untangle the feudal responsibilities that had caused so much conflict, and, as far as the English were concerned, would concentrate their territory in an expanded version of Aquitaine. This had been part of the English royal estate in France since the reign of Henry II (), and by the treaty it and Poitou became fiefdoms of Edward's oldest son, Edward the Black Prince. John was to pay three million écus as his ransom. The French were deeply unhappy with this arrangement.
In 1369, on the pretext that Edward had failed to observe the terms of the treaty, Charles V (), the son and heir of King John, declared war once again. In August a French offensive attempted to recapture castles in Normandy. Men who had fought in earlier English campaigns, and had already won fortune and fame, were summoned from their retirements, and new, younger men were given commands. Events went poorly for England almost from the start: James Audley and John Chandos, two important English commanders, were killed in the first six months; while the French made territorial gains in the west, re-occupying the strategic provincial capital of Poitiers and capturing many castles.
French strategy
This period of the Hundred Years' War, starting in 1369 and known as the Carolinian phase, was significantly different from the previous one. The French were well prepared militarily, and immediately went on the offensive. Charles was well situated in terms of financial and human resources. Edward III was growing senile, his heir was crippled by illness, and once the turmoil of the previous phase of the war had subsided Charles was able to benefit from France having three times the population and wealth of England. The French also benefited from technological improvements, such as in barding, the armouring of horses.
Fighting during this phase took place largely in Aquitaine, meaning the English had extremely long borders to defend. These were easy for small French parties to penetrate, which they did to great effect. They relied on Fabian tactics: avoiding pitched battles and using attrition to wear down the English and only attacking dispersed or isolated English forces. This was now an offensive war for the French, and the English were ill-prepared for it.