No sooner had the treaty between John and the pope been ratified in May 1213 than Verraccio announced to Philip that he would have to abandon his expedition against John, since to attack a faithful vassal of the Holy See would constitute a mortal sin. Philip argued in vain that his plans had been drawn up with the consent of Rome, that his expedition was in support of papal authority that he only undertook on the understanding that he would gain a plenary indulgence; he had spent a fortune preparing for the expedition. The papal legate remained unmoved, but Verraccio did suggest an alternative. The Count of Flanders had denied Philip's right to declare war on England while King John was still excommunicated, and that his disobedience needed to be punished. Philip eagerly accepted the advice, and quickly marched at the head of his troops into the territory of Flanders.