According to what is probably a legend, at the urging of the monks of San Juan de la Peña Peter planned to join on the Crusade of 1101 and make a pilgrimage to Jerusalem, but Pope Paschal II refused to allow it and ordered him to make war on Zaragoza instead. Peter, probably aided by knights from France and Catalonia, certainly did make war on Zaragoza in 1101, in a campaign that lasted the whole year. He may have been inspired by the First Crusaders, since contemporary accounts of the 1101 campaign call him a "cross-bearer" ("crucifer"). The size of his forces so impressed a contemporary scribe in León that he remarked in the dating formula of a document of 12 February that "Peter, Aragonese king, with his infinite multitude of armed men, the city of Zaragoza, with Christ's banner, fought". By June Peter had begun the siege of Zaragoza itself. For the siege he had a fortress built named Juslibol (a corruption of the Latin slogan "Deus lo volt" wills it used by the First Crusaders) and ringed the city with banners bearing the cross. In August he was conducting a "razzia" (raid) as far south as Alpenes and the river Ebro, but the campaign was eventually aborted due to insufficient cavalry. By the end of the year he had expanded Aragon and Navarre in the west almost as far as the walls of Zaragoza and Tudela, though the cities both remained in Muslim hands.