structural:expansion, quality:corruption
Preparations

When Mehmed II succeeded his father in 1451, he was 19 years old. Many European courts assumed that the young Ottoman ruler would not seriously challenge Christian hegemony in the Balkans and the Aegean. In fact, Europe celebrated Mehmed coming to the throne and hoped his inexperience would lead the Ottomans astray. This calculation was boosted by Mehmed's friendly overtures to the European envoys at his new court. But Mehmed's mild words were not matched by his actions. By early 1452, work began on the construction of a second fortress (Rumeli hisarı) on the European side of the Bosphorus, several miles north of Constantinople. The new fortress sat directly across the strait from the Anadolu Hisarı fortress, built by Mehmed's great-grandfather Bayezid I. This pair of fortresses ensured complete control of sea traffic on the Bosphorus and defended against attack by the Genoese colonies on the Black Sea coast to the north. In fact, the new fortress was called Boğazkesen, which means "strait-blocker" or "throat-cutter". The wordplay emphasizes its strategic position: in Turkish boğaz means both "strait" and "throat". In October 1452, Mehmed ordered Turakhan Beg to station a large garrison force in the Peloponnese to block Thomas and Demetrios (despotes in Southern Greece) from providing aid to their brother Constantine XI Palaiologos during the impending siege of Constantinople. Karaca Pasha, the beylerbeyi of Rumelia, sent men to prepare the roads from Adrianople to Constantinople so that bridges could cope with the massive cannons. Fifty carpenters and 200 artisans also strengthened the roads where necessary. The Greek historian Michael Critobulus quotes Mehmed II 's speech to his soldiers before the siege:

My friends and men of my empire! You all know very well that our forefathers secured this kingdom that we now hold at the cost of many struggles and very great dangers and that, having passed it along in succession from their fathers, from father to son, they handed it down to me. For some of the oldest of you were sharers in many of the exploits carried through by them—those at least of you who are of maturer years—and the younger of you have heard of these deeds from your fathers. They are not such very ancient events nor of such a sort as to be forgotten through the lapse of time. Still, the eyewitness of those who have seen testifies better than does the hearing of deeds that happened but yesterday or the day before.