 Complete the following phrase:  A new pope - Innocent IV - was elected. At first, Frederick was content with the election since Innocent had relatives in the Imperial camp. However, the new Pope immediately turned against Frederick. When the City of Viterbo rebelled, the Pope backed the Guelphs. Frederick immediately marched to Italy and besieged Viterbo. The pope signed a peace treaty with the emperor, relieving the city. However, after the Emperor left the Cardinal Raniero Capocci, as the leader of Viterbo, had the garrison massacred. The Pope made another treaty but he immediately broke it and continued to back the Guelphs, supporting Henry Raspe, Landgrave of Thuringia as King of the Romans and soon plotted to have Frederick killed. When the attempt failed the pope fled to Liguria. Soon the tide turned against the imperial party as the Lombard city of Parma rebelled and Enzo - who had not been present - asked his father for help. Frederick and Ezzelino III da Romano, the Tyrant of Verona, besieged the city. However the imperial camp was ambushed by the Guelphs and in the ensuing 