Four days after the French had arrived before Hennebon they were joined by Don Louis, who had been severely wounded in the fight near Quimperlé, and had lain for six weeks at Rennes. Sixteen great engines at once began to cast stones against the walls, but Sir Walter caused sand-bags to be lowered, and so protected the walls from the attack that little damage was done. The garrison, confident in their powers to resist, taunted the assailants from the walls, and specially enraged the Spaniards and Don Louis by allusions to the defeat at Quimperlé. So furious did the Spanish prince become that he took a step unprecedented in those days of chivalry. He one morning entered the tent of Charles of Blois, where a number of French nobles were gathered, and demanded a boon in requital of all his services. Charles at once assented, when, to his surprise and horror, Prince Louis demanded that two English knights, Sir John Butler and Sir Hubert Frisnoy, who had been captured in the course of the campaign and were kept prisoners at Faouet, should be delivered to him to be executed. "These English," he said, "have pursued, discomforted, and wounded me, and have killed the nephew whom I loved so well, and as I have none other mode of vengeance I will cut off their heads before their companions who lie within those walls." Charles of Blois and his nobles were struck with amazement and horror at the demand, and used every means in their power to turn the savage prince from his purpose, but in vain. They pointed out to him that his name would be dishonored in all countries where the laws of chivalry prevailed by such a deed, and besought him to choose some other boon. Don Louis refused to yield, and Charles of Blois, finding no alternative between breaking his promise and delivering his prisoners, at last agreed to his request. The prisoners were sent for, and were informed by Don Louis himself of their approaching end. At first they could not believe that he was in earnest, for such a proceeding was so utterly opposed to the spirit of the times that it seemed impossible to them. Finding that he was in earnest they warned him of the eternal stain which such a deed would bring upon his name. The Spaniard, however, was unmoved either by their words or by the entreaties of the French nobles, but told them that he would give them a few hours to prepare for death, and that they should be executed in sight of the walls after the usual dinner hour of the army. In those days sieges were not conducted in the strict manner in which they are at present, and non-combatants passed without difficulty to and fro between town and camp. The news, therefore, of what was intended speedily reached the garrison, whom it filled with indignation and horror. A council was immediately called, and Sir Walter Manny proposed a plan, which was instantly adopted.