The success of the revolt finally pushed Maximilian into action. In early August, a massive Imperial army, accompanied by bodies of French and Spanish troops, set out from Trento into the Veneto. Because of a lack of horses, as well as general disorganization, Maximilian's forces would not reach Padua until September, giving Pitigliano the time to concentrate such troops as were still available to him in the city. The Siege of Padua began on 15 September; although French and Imperial artillery successfully breached Padua's walls, the defenders managed to hold the city until Maximilian, growing impatient, lifted the siege on 30 September and withdrew to Tyrol with the main part of his army.