In 1606, a conflict between Venice and the Holy See began with the arrest of two clerics accused of petty crimes, and with a law restricting the Church's right to enjoy and acquire landed property. Pope Paul V held that these provisions were contrary to canon law, and demanded that they be repealed. When this was refused, he placed Venice under an interdict. The Republic paid no attention to the interdict or the act of excommunication, and ordered its priests to carry out their ministry. It was supported in its decisions by the Servite monk Paolo Sarpi, a sharp polemical writer who was nominated to be the Signoria's adviser on theology and canon law in 1606. The interdict was lifted after a year, when France intervened and proposed a formula of compromise. Venice was satisfied with reaffirming the principle that no citizen was superior to the normal processes of law.
The latter half of the 17th century saw also prolonged wars with the Ottoman Empire: in the Cretan War (1645–1669), after a heroic siege that lasted 24 years, Venice lost its major overseas possession, the island of Crete, while it made some advances in Dalmatia. In 1684 however, taking advantage of the Ottoman involvement against Austria in the Great Turkish War, the Republic initiated the Morean War, which lasted until 1699 and in which it was able to conquer the Morea peninsula in southern Greece.
The Decline of The Republic of Venice
These gains did not last, however: in December 1714, the Turks began the last Turkish–Venetian War, when the Morea was "without any of those supplies which are so desirable even in countries where aid is near at hand which are not liable to attack from the sea". The Turks took the islands of Tinos and Aegina, crossed the isthmus, and took Corinth. Daniele Dolfin, commander of the Venetian fleet, thought it better to save the fleet than risk it for the Morea. When he eventually arrived on the scene, Nauplia, Modon, Corone and Malvasia had fallen. Levkas in the Ionian islands, and the bases of Spinalonga and Suda on Crete which still remained in Venetian hands, were abandoned.
The Turks finally landed on Corfù, but its defenders managed to throw them back. In the meantime, the Turks had suffered a grave defeat by the Austrians in the Battle of Petrovaradin on 5 August 1716. Venetian naval efforts in the Aegean and the Dardanelles in 1717 and 1718, however, met with little success. With the Treaty of Passarowitz (21 July 1718), Austria made large territorial gains, but Venice lost the Morea, for which its small gains in Albania and Dalmatia were little compensation. This was the last war with the Ottoman Empire. By the year 1792, the once great Venetian merchant fleet had declined to a mere 309 merchantmen. The decline of Venice as a seaborne empire should not obscure the fact that the Republic remained in undisturbed possession of its vast and rich continental domain north of the Po valley extending west almost to the walls of Milan. Treviso, Vicenza, Padova, Verona, Brescia, Bergamo, not to mention Venice itself, benefited handsomely from the Pax Venetiae (Venetian peace) throughout the allegedly decadent 18th century.