Its last domains in Thrace were being overrun by the Ottomans, who in 1365 captured Adrianople (modern Edirne). Seeking aid from the West, in 1369 John V visited Pope Urban V that summer, and following that he sailed to Venice, where he negotiated a treaty in which the Venetians would cancel the emperor's debt in return for the island of Tenedos. On leaving Byzantine soil he left his two sons, Andronikos IV and Manuel, to manage Constantinople and Thessalonica respectively.[3] Andronikos IV, the elder son and co-emperor, however refused to hand over Tenedos to the Venetians as agreed, and the Emperor was detained by the Venetians for two years until Manuel intervened on his behalf.[4]