This was a breach of the treaty of Bretigny, and De Montford at once sent to the Black Prince for assistance. The prince did not treat the conduct of Charles as a breach of the treaty, and took no part himself in the war, but permitted Sir John Chandos, who was a personal friend of De Montford, to go to his aid. De Montford's army, after the arrival of Chandos with a force of two hundred spears, amounted to but sixteen hundred men-at-arms and from eight hundred to nine hundred archers, while Charles of Blois had four thousand men-at-arms and a proportionate number of infantry. De Montford tried to negotiate. He offered to divide the dukedom, and to agree that in case he died childless it should revert to the family of Charles. Charles, however, refused all terms, even to grant his adversary's request to put off the battle until the morrow, so as to avoid violating the Sabbath; and having given orders that all prisoners taken in the battle should be hung, he advanced upon De Montford. Both forces were divided in four bodies. The first on De Montford's side was commanded by Sir Robert Knolles, the second by Oliver de Clisson, the third by Chandos and De Montford, the fourth by Sir Hugh de Calverley. Du Guesclin led the front division of Charles' army, the Counts of Auxerre and Joigny the second, Charles himself the third, and the Lords of Roye and Rieux the reserve. The ducal arms of Brittany were displayed on both sides. By slow degrees the two armies closed with each other in deadly strife. Both parties had dismounted and fought on foot with lances shortened to five feet. Du Guesclin and his division attacked that of Knolles. Auxerre fell upon De Clisson, while the divisions of the two rival princes closed with each other. After desperate fighting numbers prevailed. De Montford was driven back, but Calverley advanced to his aid, fell upon the rear of the French, threw them into disorder, and then having rallied De Montford's men, retired to his former position in readiness to give succor again where it might be needed. In the mean time Clisson had been engaged in a desperate struggle with the Count of Auxerre, but was obtaining no advantage. Clisson himself had received the blow of a battle-ax which had dashed in the visor of his helmet and blinded forever one of his eyes. He was still leading his men, but the enemies' superior numbers were pressing him back, when Chandos, the instant the assistance of Calverley had relieved De Montford's division, perceiving his danger, drew off a few men-at-arms, and with them fell upon the rear of the Count of Auxerre, and dashing all who opposed him to the ground with his battle-ax, cleft his way to the very center of the enemy. Pressed by De Clisson in front and broken by the sudden attack of Chandos in the rear, the French division gave way in every direction. Auxerre was desperately wounded, and he and De Joigny both taken prisoners.