A real Doge Coin.  Great detail on the face of the Doge.  Francesco Foscari was Doge when Constantinople fell to the Ottoman Turks in 1453.  The last Emperor Constantine XI died fighting in the city, but his daughter escaped to Venice under the protection of Foscari.
 
Earlier, in August 1450, Constantine XI had raised taxes on the Venetians who had their own quarter of Constantinople (recall that they had brought the Fourth Crusade there to sack it in 1203 under Doge Enrique Dandolo).  The Venetians then threatened Constantine XI to transfer their trade to another port, perhaps one under Ottoman control, and despite Constantine writing to Doge Foscari in October 1450, the Venetians were unconvinced and signed a formal treaty with Mehmed II in 1451.  Soon it was curtains for Constantinople.