Why did the French attackers fail to capture Padua in 1509?

The French attackers failed to capture Padua in 1509 because the city’s defenses had been modernized to counter the effectiveness of siege artillery.1

Entrusted with the city's defense, the monk-engineer Fra Giocondo implemented a new defensive strategy that rendered traditional bombardment ineffective:1

• Lowered Walls: He cut down the city’s high, vertical medieval walls, which were highly vulnerable to cannon fire.1
• Broad Ditch: He surrounded the city with a wide ditch designed to be swept by flanking fire from low-set gunports located in projections extending into the ditch.1
• Resilient Ramparts: By replacing vulnerable stone walls with low, thick ramparts, the defenders ensured that French cannon fire made little impression on the fortifications.1

Faced with these innovations, the French and their allies were unable to breach the defenses, leading to several failed, costly assaults before they ultimately withdrew.1