But on the death of this good prince, the ambition of the count of Mountfort broke through all these regulations, and kindled a war, not only dangerous to Brittany, but to a great part of Europe. While Charles of Blois was soliciting at the court of France the investiture of the duchy, Mountfort was active in acquiring immediate possession of it; and by force or intrigue he made himself master of Rennes, Nantz, Brest Hennebonne, and all the most important fortresses, and engaged many considerable barons to acknowledge his authority.[**] Sensible that he could expect no favor from Philip, he made a voyage to England, on pretence of soliciting his claim to the earldom of Richmond, which had devolved to him by his brother’s death; and there, offering to do homage to Edward, as king of France, for the duchy of Brittany, he proposed a strict alliance for the support of their mutual pretensions. * Froissard, liv. i. chap. 64. ** Froissard, liv. i. chap. 65, 66, 67, 68. Edward saw immediately the advantages attending this treaty: Mountfort, an active and valiant prince, closely united to him by interest, opened at once an entrance into the heart of France, and afforded him much more flattering views than his allies on the side of Germany and the Low Countries, who had no sincere attachment to his cause, and whose progress was also obstructed by those numerous fortifications which had been raised on that frontier. Robert of Artois was zealous in enforcing these considerations: the ambitious spirit of Edward was little disposed to sit down under those repulses which he had received, and which he thought had so much impaired his reputation; and it required a very short negotiation to conclude a treaty of alliance between two men, who, though their pleas with regard to the preference of male or female succession were directly opposite, were intimately connected by their immediate interests.[*] As this treaty was still a secret, Mountfort, on his return, ventured to appear at Paris, in order to defend his cause before the court of peers; but observing Philip and his judges to be prepossessed against his title, and dreading their intentions of arresting him, till he should restore what he had seized by violence, he suddenly made his escape; and war immediately commenced between him and Charles of Blois.[**] Philip sent his eldest son, the duke of Normandy, with a powerful army, to the assistance of the latter; and Mountfort, unable to keep the field against his rival, remained in the city of Nantz, where he was besieged. The city was taken by the treachery of the inhabitants; Mountfort fell into the hands of his enemies, was conducted as a prisoner to Paris, and was shut up in the tower of the Louvre.[***] * Froissard, liv. i. chap, 69. ** Froissard, liv. i. chap. 70, 71. *** Froissard, liv. i. chap 73.