fter the death of John VIII, it was his brother, Constantine XI Palaiologos Dragas, who ascended the throne. In spite of his courage and abilities, it was no longer possible for Constantine to save the Empire. Constantinople, by now virtually identified with the Empire, occupied the very heart of the Ottoman state, separating its Asian possessions from its European ones. The primal aim, therefore, of the new Sultan, Mehmed II, who had succeeded his father, Murad II, after the latter's death in February 1451, was to remove this foreign body and make of Constantinople the centre of the nascent Ottoman Empire. He immediately began preparations for the conquest of the city, which included the construction of a strong fortress on the Bosporos.

Following the example of his predecessors, Constantine sought assistance from the West. However, the conflicting interests of the Western powers with regard to the fate of Byzantium deterred them from dispatching help to Constantine. Moreover, the efforts of the Byzantine Emperor to ensure the Pope's aid in conformity with the decisions made at the Council of Ferrara and Florence in December 1452 only succeeded in infuriating the people, who, faithful to Orthodoxy, went so far as to declare, in the words of a high Byzantine official, that they would rather come to terms with the Turks than to submit to Rome. The Byzantine state, thoroughly exhausted in every way, was now living its last moments.