his own son with Guelders and Zutphen. Within months and with his father's skilled use of field artillery, Philip conquered the whole land and Charles of Egmond was forced to prostrate himself in front of Philip. Maximilian would like to see the Guelders matter to be dealt with once and for all, but as Charles later escaped and Philip was at haste to make his 1506 fatal journey to Spain, troubles would soon arise again, leaving Margaret to deal with the problems. Maximilian was exasperated by the attitude of Philip (whom, in Maximilian's imagination, was probably influenced by insidious French agency) and the Estates, whom he considered to be unbelievably nonchalant and tightfisted about a threat to their own country's security. Philip's death in Burgos was a heavy blow personally (Maximilian's entourage seemed to have concealed the incident from him for more than ten days) and also politically, as by this time, he had become his father's most important international ally, although he retained his independent judgement. All their joint ventures fell apart, including the planned Italian expedition in 1508. The Estates preferred to maintain peace with France and Guelders. But Charles of Egmont, the de facto lord of Guelders continued to cause trouble. In 1511, Margaret made an alliance with England and besieged Venlo, but Charles of Egmont invaded Holland so the siege had to be lifted. James D. Tracy opines that Maximilian and Margaret were reasonable in demanding more stern measures against Guelders, but their critics in the Estates General (that had continuously voted against providing funds for wars against Guelders) and among the nobles naively thought that Charles of Egmont could be controlled by maintaining the peaceful relationship with the King of France, his patron. Leading Humanists in the Netherlands like Erasmus and Hadrianus Barlandus displayed a distrust towards the government and especially the person of Maximilian, whom they believed to be a warlike and greedy prince. After the brutal 1517 campaign of Charles of Egmont in Friesland and Holland, these Humanists, in their mistaken belief, spread the stories that the emperor and other princes were concocting clever schemes and creating wars just to expand the Habsburg dominion and extracting money. By the time Margaret became Regent, Maximilian was less inclined to help regarding the Guelders matter. He suggested to her that the Estates in the Low Countries should defend themselves, forcing her to sign the 1513