In February 1243, the Emperor Frederick ordered the mustering of his army for April 1. He met the army at Capua, and in May he headed north toward Rome, where he began to attack and destroy castelli and cause as much destruction as he could. The two cardinals still in Rome fled to Anagni, and now that eight of the cardinals were assembled, they petitioned the Emperor who agreed to their request to return to his kingdom. Frederick then released Cardinal Jacobus de Pecorara, whom he had held prisoner since his capture in the Battle of Giglio in May 1241. In being accommodating, however, King Frederick expected the cardinals to be cooperative and produce a pope. And yet, they refused to start a conclave. Frederick showed his anger by launching his army against Rome. The Romans complained that the failure to elect a pope after so many months was not their fault, but that of the obstinate and quarrelsome cardinals, who were in hiding. Frederick therefore redirected his army toward the estates of the cardinals and of the Church.