[5] He played a role in the negotiations that saw the return of Argos to the Republic of Venice after its occupation by the Byzantine Despot of the Morea, Theodore I Palaiologos.
[7] Playing on Ottoman fears of a concerted Christian campaign against them in the aftermath of their disastrous defeat at Ankara, he managed to extract a number of concessions from Süleyman Çelebi in the Treaty of Gallipoli, concluded in January or early February 1403: Venice was granted a strip of territory on the Greek mainland opposite the whole length of the island of Euboea, which was a Venetian possession; the Northern Sporades were ceded to the Byzantines; the transfer of the County of Salona to the Knights Hospitaller was ratified; the tribute levied on the Marquisate of Bodonitsa was not raised; and finally the Sultan promised to restore Athens to Venice.
In the event, the latter promise remained a dead letter, and Venice was forced to recognize Acciaioli rule over Athens a few years later.
[10] Despite his great diplomatic ability and prestige, even Zeno found it difficult to manoeuvre among the various competing powers of the era.
Andros managed to escape relatively unscathed, but in return Zeno was forced to pay tribute and provide harbour and shelter for the Turkish ships there.