Now that the papal participation in the plot against him had become clear, Frederick wrote to the noblemen to inform them of the pope's vile behavior, and marched with an army to Lyon in 1247. Once he had arrived in
Turin, however, he received news that Parma had rebelled again. According to
Salimbene di Adam, a group of Guelph Parmigian refugees, who had taken shelter in Piacenza, was led by Ugo di Sanvitale (the new bishop of Parma's brother) and Bernardo di Rolando Rossi (the pope's brother-in-law and a former collaborator of Frederick). They defeated the imperial garrison under the imperial
podestà Enrico Testa near
Borghetto di Taro and occupied the city with no resistance, since the garrison of
Enzio of Sardinia, Frederick's son, was besieging
Quinzano. Frederick immediately diverted his troops to Emilia, and at the same time he called for reinforcements from friendly lords and communes. The imperial army was also joined by Enzio, who raised the siege of Quinzano, and by a
Cremonese contingent led by
Ezzelino III da Romano, as well as by soldiers from
Padua,
Verona, and
Vicenza. The pope did his best to send help to Parma from cities faithful to him, such as
Milan,
Piacenza,
Mantua, and
Ferrara.
Gregorio di Montelongo was able to reach the city, organizing its defense with Bernardo Rossi and
Gilberto da Gente. Perhaps due to a shortage of siege weapons, Frederick decided to take the city by starvation. The Guelphs were however determined to resist thanks to the papal help, and the siege dragged on for eight months. Frederick ordered the construction of an entrenched camp near
Grola, calling it
Victoria (Latin for "victory"), including houses, palaces, and a church, declaring that it would become the seat of his kingdom after the fall of Parma. However, several noblemen abandoned him. Further, on 12 February 1248 Gregorio di Montelongo launched a sortie: after the sufferings they had faced during the siege, the people in arms followed the image of the Holy Virgin and attacked, Frederick was hunting in the
Taro valley, and Vittoria was destroyed. He took refuge at
Borgo San Donnino, and then moved to Cremona. ==Aftermath==