Venice lost half the Christian Empire and had them slaughtered !!

The Turks could notvtake Constantinople ..
Their blockading fleet  had been smashed by the Byzantine fleet.
The siege was failing , they could not break into Constan ..
Then the Venetians sold them heavy cannon !! Which smashed the walls in and allowed the Ottoman Army on to wipe out Christianity ..
The Byzantines could not purchase cannon because their gold and treasures had been plundered by the Pope's Army of Crusaders on their way to Jerusalem ..
A double whammy that lost half the Christian Empire to the Ottomans !!
Lest we forget .