This prosperity excited the jealousy of the Genoese, as it interfered with a commerce which they had hitherto monopolized.

When the Venetians had been chased from Constantinople by the Emperor Michael Paleologus, they retained several fortresses in the Black Sea, which enabled them to continue their trade with the Tartars in that sea, and to frequent the fair of Tana.

The Genoese, who were masters of Pera, a suburb of Constantinople, would willingly have joined the Greeks in expelling their Italian rivals altogether from the Black Sea; and privateering hostilities actually commenced between the two republics, which, in 1350, extended to the serious aspect of a national war.
The winter of that year was passed on both sides in preparations.

The Venetians sent ambassadors to the King of Arragon, who had some differences with the Genoese about the Island of Sardinia, and to the Emperor of Constantinople, who saw with any sensation in the world but delight the flag of Genoa flying over the walls of Pera.

A league between those three powers was quickly concluded, and their grand, common object was to destroy the city of Genoa.
It was impossible that these great movements of Venice should be unknown at Padua.