Fall of Constantinople - Preparations

Preparations

When Sultan Mehmed II succeeded his father in 1451, it was widely believed (or hoped, perhaps, by some) that the young ruler, then 19 years old, would prove incapable—and that he would pose no great threat to Christian possessions in the Balkans and the Aegean. This optimism was reinforced by friendly assurances made by Mehmed to envoys sent to his new court. But Mehmed's actions spoke louder than his mild words. Beginning early in 1452 he built a second Ottoman fortress, named Rumeli Hisarı, on the Bosphorus; this was done on the European side several miles north of Constantinople, and set directly across the strait from the similar fortress Anadolu Hisarı, which his great grandfather Bayezid I had previously built on the Asian side. This fortress-pair gained for the Turks complete control of sea traffic on the Bosphorus; specifically, it prevented help from the north, the Genoese colonies on the Black Sea coast, from reaching Constantinople. (The new fortress was also known as Boğazkesen, which held the dual meanings 'strait-blocker' or 'throat-cutter', emphasizing its strategic position.) In October 1452, Mehmed ordered Turakhan Beg to lead a large force into the Peloponnese and remain there to keep the despots Thomas and Demetrios from assisting their brother Constantine during the impending siege of Constantinople.

Byzantine Emperor Constantine XI understood Mehmed's intentions, and turned to western Europe for help; but now the fruits of centuries of war and enmity between the eastern and western churches would be tolled. Since the mutual excommunications of 1054, the Pope in Rome was committed to imposing dominion over the eastern church. Nominal union had been negotiated in 1274, (at Lyon), and indeed, some Palaiologoi emperors (Latin, Palaeologan) had since been received into the Latin church. And, Emperor John VIII Palaiologos had recently negotiated union with Pope Eugene IV, with the Council of Florence of 1439 proclaiming a Bull of Union. These events, however, stimulated a massive propaganda initiative by anti-unionist partisans in Constantinople; and the population as well as the laity and leadership of the Byzantine Church became bitterly divided. Latent ethnic hatreds between Greeks and Italians—stemming from the events of the sack of Constantinople in 1204 by the Latins—played a significant role. Finally, the Union failed, greatly annoying Pope Nicholas V and the hierarchy of the Roman church.

In the summer of 1452, when Rumeli Hisari was completed and the threat had become imminent, Constantine wrote to the Pope, promising to implement the Union, which was declared valid by a half-hearted imperial court on Tuesday 12 December 1452. Although he was eager for an advantage, Pope Nicholas V did not have the influence the Byzantines thought he had over the Western Kings and Princes, some of whom were wary of increasing Papal control, and these had not the wherewithal to contribute to the effort, especially in light of the weakened state of France and England from the Hundred Years' War, Spain being in the final part of the Reconquista, the internecine fighting in the German Principalities, and Hungary and Poland's defeat at the Battle of Varna of 1444. Although some troops did arrive from the mercantile city states in the north of Italy, the Western contribution was not adequate to counterbalance Ottoman strength. Some Western individuals, however, came to help defend the city on their own account. One of these was an accomplished soldier from Genoa, Giovanni Giustiniani, who arrived with 700 armed men in January 1453. A specialist in defending walled cities, he was immediately given the overall command of the defense of the land walls by the emperor. Around the same time, the captains of the Venetian ships which happened to be present in the Golden Horn offered their services to the Emperor, barring contrary orders from Venice, and Pope Nicholas undertook to send three ships laden with provisions, which set sail near the end of March. In Venice, meanwhile, deliberations were taking place concerning the kind of assistance the Republic would lend to Constantinople. The Senate decided upon sending a fleet, but there were delays, and when it finally set out late in April, it was already too late for it to be able to partake in the battle. Further undermining Byzantine morale, seven Italian ships with around 700 men slipped out of the capital at the moment when Giustiniani arrived, men who had sworn to defend the capital. At the same time, Constantine's attempts to appease the Sultan with gifts ended with the execution of the Emperor's ambassadors — even Byzantine diplomacy could not save the city.

Fearing a possible naval attack along the shores of the Golden Horn, Emperor Constantine XI ordered that a chain be placed at the mouth of the harbour. This chain, which floated on wooden logs, was strong enough to prevent any Turkish ship from entering the harbour. This device was one of two which gave the Byzantines some hope of extending the siege until the possible arrival of foreign help. This strategy was enforced because in 1204 the armies of the 4th Crusade successfully circumvented Constantinople's land defenses by breaching the Golden Horn Wall. Another strategy employed by the Byzantines was the repair and fortification of the Land Wall (Theodosian Walls). Emperor Constantine deemed it necessary to ensure that the Blachernae district's wall were the most fortified because that section of the wall protruded northwards. The land fortifications comprised a 60 ft (18 m) wide moat fronting inner and outer crenellated walls studded with towers every 50–60 yards.