On 6 July 1356 Prince Edward set out on another expedition, undertaken with the intention of passing through France to Normandy, and there giving aid to his father's Norman allies, the party headed by the king of Navarre and Geoffrey Harcourt. In Normandy he expected, he says, to be met by his father, He crossed the Dordogne at Bergerac on 4 August, and rode through Auvergne, Limousin, and Berry, plundering and burning as he went until he came to Bourges, where he burnt the suburbs but failed to take the city. He then turned westward and made an unsuccessful attack on Issoudun on 25–27 August. Meanwhile, King John II was gathering a large force at Chartres, from which he was able to defend the passages of the Loire, and was sending troops to the fortresses that seemed in danger of attack. From Issoudun the prince returned to his former line of march and took Vierzon. There he learnt that it would be impossible for him to cross the Loire or to form a junction with Lancaster, who was then in Brittany. Accordingly he determined to return to Bordeaux by way of Poitiers, and after putting to death most of the garrison of the castle of Vierzon set out on 29 August towards Romorantin.