who favored a more vigorous pursuit of the retreating Lannoy, the king's army then advanced on Pavia, where Antonio de Leyva remained with a sizable garrison. The main mass of French troops arrived at Pavia on 24 October. Siege of Pavia By 2 November, Montmorency had crossed the Ticino River and invested Pavia from the south, completing its encirclement. Inside were about 9,000 men, mainly mercenaries whom Antonio de Leyva was forced to pay by melting down the gold and silver treasures in the city's churches. The French bombardment of Pavia began on 6 November. On 21 November, Francis attempted an assault on the city through two of the breaches but was beaten back with heavy casualties. Hampered by rainy weather and a lack of gunpowder, the French decided to wait for the defenders to starve. In early December, a Spanish force commanded by Hugo of Moncada landed near Genoa, intending to intervene in a conflict between pro-Valois and pro-Habsburg factions in the city. Francis dispatched a larger force under Michele Antonio I of Saluzzo to intercept them. Confronted by the more numerous French and left without naval support by the arrival of a pro-Valois fleet commanded by Andrea Doria, the Spanish troops surrendered. In January 1525, Lannoy was reinforced by the arrival of Frundsberg with fresh landsknechts and cavalrymen, which enable him to renew the offensive. The French outpost at San Angelo was taken, cutting the lines of communication between Pavia and Milan, while a separate column of landsknechts advanced on Belgiojoso and, despite being briefly pushed back by a raid led by Medici and Bonnivet, occupied the town. On 22 January the main imperial army at Lodi simulated an offensive against Milan, which failed to lure away the French. The Imperial commanders marched with 22,000 infantry, 2,300 cavalry, and 17 cannon to Pavia from Lodi on 25 January. Early in February, a thousand Italian soldiers were defeated at Alessandria before they could reach the French at Pavia. The French position was weakened when Medici returned to Pavia on 8 February and replenished the garrison's supply of gunpowder, gathered by the Duke of Ferrara. It was further weakened by the desertion of 2,000 Germans and the departure of nearly 5,000 Grisons Swiss mercenaries, who returned to their cantons in order to defend their own region following the capture of the town of Chiavenna by Milanese troops. Francis was encamped