eight miles north of Constantinople. Originally known in Turkish as Boğaz Kesen, or ‘Cut Throat’, and later called Rumeli Hisarı, the ‘Castle of Europe’, it was built directly across the strait from the fortress built ın 1394 by Beyazit I, known as Anadolu Hisarı, the ‘Castle of Asia’. Constantine sent an embassy to Mehmet complaining that the sultan was violating their treaty by building a fortress on Byzantine territory. Mehmet replied, according to Doukas, ‘I take nothing from the City. Beyond the fosse she owns nothing. If I desire to build a fortress…the emperor has no right to stop me.’
Early in the spring of 1452 Mehmet left Edirne for Gallipoli, where the Ottoman fleet was based. There, according to Kritoboulos, ‘he filled thirty triremes and armed them fully as for a naval fight… He prepared other ships to carry the equipment, and sent them up from Gallipoli to the Bosphorus.’ Mehmet then crossed the Dardanelles with his troops and led them along the Asian side of the strait to the Bosphorus. There he crossed over to the European side from Anadolu Hisarı, to the place that came to be known as Rumeli Hisarı, where he had decided to build his fortress.
Construction of the fortress began on 15 April 1452. Kritoboulos writes of how Mehmet ‘marked out with stakes the location where he wished to build, planning the position and the size of the castle, the foundations, the distance between the main towers and the smaller turrets, also the bastions and breastworks and gates, and every other detail as he had carefully worked it out in his mind’.
An army of workmen conveyed building material to the site, including architectural members from ruined Byzantine monuments in the vicinity. Doukas reports that ‘as they were removing several columns from the ruins of the Church of the Archangel Michael, some of the inhabitants of the City, angered by what was happening, tried to stop the Turks, but they were all captured and put to death by the sword’.
Mehmet’s cavalrymen grazed their horses in the surrounding fields, and when the local Greek farmers tried to drive the animals away a fight broke out in which several men on both sides were killed. The following day Mehmet sent his commander Kaya Bey to punish the locals, forty of whom were killed, according to Doukas, who noted: ‘This was the beginning of the conflict that led to the destruction of the Romans.’
When news of the massacre reached Constantine he closed the gates of Constantinople and imprisoned all the Turks who were then in the city. The prisoners included some eunuchs from Edirne Sarayı who happened to be visiting the city. The eunuchs appealed to Constantine, saying that if they did not return to Edirne they would be executed, and so three days later he relented and released them along with the other prisoners. He then sent an embassy in a last attempt to come to terms with Mehmet, who imprisoned the envoys and had them beheaded, thus making a virtual declaration of war.
Mehmet had hired a Hungarian military engineer named Urban, who built for him a large cannon that he claimed could destroy the walls of Babylon. As soon as Rumeli Hisarı was finished, on 31 August 1452, the cannon was placed on one of its main towers. Mehmet then proclaimed that all ships passing on the Bosphorus had to stop for inspection by the commandant of Rumeli Hisarı, otherwise they would be fired upon. Early in November two Venetian ships, sailing from the Black Sea with supplies for Constantinople, took advantage of a favourable north wind to pass the fortress unscathed. But two weeks later another Venetian ship was sunk by the great cannon in Rumeli Hisarı. The captain, Antonio Rizzo, and his crew were captured and brought to Mehmet at Didymoteichon, south of Edirne. Mehmet had Rizzo impaled and his crew beheaded, leaving their bodies beside the road for travellers to see and carry the news to Constantinople.
Meanwhile, Constantine had