 Complete the following phrase:  The bulwark of Christianity and other slogans put forward by the papal envoy Giuliano Cesarini, together with much more reasonable but only verbal promises of Venetian and papal fleets blockading the Dardanelles Straits, along with an enticing vision of a promise of victory in the Crusade of Varna against the Muslims, persuaded Władysław to engage his freshly victorious forces for another season of war, thus breaching the ten-year truce with the aggressive and still powerful Ottoman Empire. Despite their alleged forthcoming help, the Venetian fleet carried the Muslim army from Asia into Europe but failed to sail to Varna, a surprising move that Władysław and his most senior military commander John Hunyadi failed to anticipate. The Venetian treachery placed the huge Muslim army 60,000 under sultan Murad II in close proximity to the unsuspecting crusaders 20,000. As a result, when the 