Eventually, some time around 20 August, John gave the garrison of Breteuil free passage to the Cotentin and a huge bribe in order to persuade them to vacate Breteuil. The French army promptly marched south as all available forces were concentrated at Chartres to oppose the Black Prince. John and his army pursued the Black Prince's force, cut off their retreat and forced it to battle at Poitiers. The French army was heavily defeated by the Black Prince's smaller force and John was captured, along with most of his court and much of the nobility of France.