[1] At the time of Marsilio's youth, the Zorzi had just begun their ascendance to the higher social and political ranks of the Republic of Venice: his father is known to have been a public treasurer (camerlengo di Comùn) in 1212, and ambassador to Padua in 1216, where he signed the treaty that ended the War of the Castle of Love.
In that year, he was sent as envoy to the autonomous Greek ruler of Rhodes, Leo Gabalas, who had only recently submitted to the Nicaean Empire of John III Vatatzes.
[1][2] Marsilio concluded a treaty with Gabalas, who recognized the suzerainty of the Doge of Venice, pledged his support in the troubled Venetian colony of Crete, and forming a joint front against the Vatatzes.
[1] After his return from Rhodes, Marsilio was sent as ambassador to Ravenna, to receive a public oath by the commune and its governor to uphold the recent agreement with Venice.
[1] Marsilio then disappears from the record until the early 1240s, when he is mentioned as bailo of Venice in Acre; he likely arrived in the city with the spring convoy of 1242.
[1][7] The sources are again silent on Marsilio's life between 1244 and May 1252, when he was appointed governor of the Republic of Ragusa (modern Dubrovnik), which had just submitted to Venice, with the title of count.
[1] His tenure, which lasted until July 1254, was successful: he concluded an alliance with the Bulgarian tsar Michael II Asen against the Serb king, Stefan Uroš I, and his rule was seen as just and prudent.
[1] As a result of this success, in April 1254 the inhabitants of the nearby Dalmatian island of Curzola (Korčula) asked him to become their hereditary governor (comes perpetuus, 'perpetual count').
[1] When Marsilio died in October or November 1271, Ruggero Zorzi of the San Angelo branch, head of the Council of Forty in that year, presented himself to the procurators and received the county of Curzola.