In 1474 and 1478, Rizzo was sent to Scutari as a military engineer. Both times (during the First Venetian-Ottoman war), the Ottoman Turks had besieged the town. He was to improve the fortifications there. He was lauded for "continuously doing his patriotic duty", and received injuries. Although the citadel was lost, Rizzo was awarded a monthly pension of 1 ducat for twenty years for himself and his family.