Informed of Ottone's presence in Lombardy, Martino sent his troops to put Arona under siege. Ottone, who occupied the near Rocca of Angera, was forced to surrender on 5 May 1263. Back in Montefiascone, Ottone lost his powerful ally Urban IV, who died on October 1264.
Upon learning of Ottone's presence in Lombardy, Martino sent troops to besiege Arona. Ottone, who held the Rocca di Angera nearby, was compelled to surrender on May 5, 1263. Back in Montefiascone, Ottone lost his powerful ally Urban IV, who died in October 1264.