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.

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.

[1][2][3] The English campaigned frequently on the continent, gaining a long run of military successes against larger forces across France.

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.

[9] In 1369, on the pretext that Edward had failed to observe the terms of the treaty, Charles V (r. 1364–1380), the son and heir of King John, declared war once again.

[13] 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;[14] while the French made territorial gains in the west, re-occupying the strategic provincial capital of Poitiers and capturing many castles.

[16] 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.

To prevent the English army from dividing and going separate ways – and in what the historian Jonathan Sumption calls "a prescient precaution"[21] – the captains were required to sign a contract before they left agreeing not only to serve the King faithfully, but also not to allow any divisions to open up between them, and to make decisions collectively.

[15] Journeying through the Somme region, Knolles made a show of force outside Reims, marched to Troyes, and then swung west to approach Paris from the direction of Nemours.

As they marched, Knolles's army captured many towns, which they would then raze if the French refused to pay the ransoms the English demanded.

The former would enable him to support the Black Prince; the latter might be necessary if Edward concluded an agreement with Charles of Navarre, who was offering his lands in northern Normandy as a base for the English.

They found a leader in Sir John Minsterworth, an ambitious but unstable knight from the Welsh Marches, who mocked Knolles as "the old freebooter".

[31] Much of Knolles's strategy was based on that employed in the campaigns of the 1340s and 1350s; particularly the capturing of enemy fortresses, to either garrison them with English troops or levy a ransom.

[32][note 4] Meanwhile, the English campaign in the west, which was nominally commanded by the Black Prince and actually by John of Gaunt and the Earl of Pembroke,[34] captured Limoges after a five-day siege, taking many prisoners whom they held for ransom and seizing much booty.

[41] Their concern to keep pillaging the countryside was in large part forced upon them: the government had only paid their and their army's wages for thirteen weeks, and they were expected not just to live off the land, but pay themselves from it.

[27][note 7] Knolles threatened to leave, and when the other English commanders refused to join him, did so, taking the largest retinue from the army with him[41] – "doubtless with considerable booty", remarks the medievalist Kenneth Fowler.

[46] On the evening of 3 December, Knolles was some way to the west, Grandison's force of between 600 and 1,200 was spread out along a river between Pontvallain and Mayet, and Fitzwalter was several miles to the south.

[46] Charles considered that Guesclin had the necessary skills in leading small forces and in irregular warfare to implement the Fabian approach he had decided on.

One of the most important aspects of the Pontvallain campaign was the speed with which the French moved: Guesclin and his forces reached Le Mans, a journey of 100 miles (160 km), two days later.

[49][52] At Le Mans, Guesclin received intelligence that Grandison's force was nearby at Mayet, but was on the move in an attempt to join with Knolles.

The English were taken by surprise and Sumption speculates that Grandison may only have had time to form rough lines with his men before fierce close-quarters fighting began.

[18] The English attempted an escape through the woods,[49] but were unable to retreat northwards, where the slightly higher ground may have provided them with a defensible position.

Soon, with heavy losses on both sides, Grandison's force was penned in and wiped out beneath the walls of the Château de la Faigne.

Fitzwalter managed to avoid being surprised in open ground as Grandison had been, and marched south, intending to take refuge within the fortified Vaas Abbey.

[55] Many of Knolles's men abandoned their positions garrisoning castles, including Rillé and Beaufort la Vallée, and also headed to the Loire.

This group continued to be pursued by Guesclin, now joined again by Sancerre, deep into Poitou, where it was eventually run to ground outside Bressuire Castle.

Guesclin made his way back to Saint-Maur where he negotiated with the English inside the abbey – led by Sir John Cresswell and Calveley – and arranged their release on payment of a ransom.

[64] Many knights were captured by the French, including John Clanvowe, Edmund Daumarle and William Neville,[65] and were conveyed to Paris in open carts and strictly imprisoned.

[66] Fitzwalter was held prisoner until he was able to raise a ransom by mortgaging his Cumberland estates to Edward III's mistress Alice Perrers on ruinous terms.