After the Sixth Crusade, Frederick II quelled a rebellion led by his son Henry in Germany and soon invaded Lombardy with a large army. Pope Gregory IX attempted to stop the invasion with diplomacy but failed. Frederick defeated the Lombard League in the Battle of Cortenuova and refused any peace treaty with any of the Guelph States. He then laid siege to Brescia but was forced to lift it. He was then excommunicated by the Pope, and in response expelled the friars from Lombardy and placed his son Enzo as Imperial vicar in Italy; he quickly annexed Romagna, Marche, the Duchy of Spoleto, and part of the Papal States. In the meantime Frederick marched through Tuscany hoping to capture Rome, however, he was forced to retreat, sacking the city of Benevento. Soon however the Ghibelline city of Ferrara fell and Frederick once more marched into Italy capturing Ravenna and Faenza. The pope called a council but an Imperial-Pisan fleet defeated a Papal fleet carrying Cardinals and prelates from Genoa in the Battle of Giglio and then Frederick continued marching towards Rome. However Pope Gregory soon died and Frederick, seeing the war being directed against the Church and not the pope, withdrew his forces, releasing two cardinals from Capua, although Frederick did again march against Rome over and over throughout 1242 and 1243.