The most prominent of the European defenders of Constantinople was the chief admiral of the northern Italian republic of Genoa, Giustiniani, who was placed in charge of the final defenses of the great walled city of Constantinople. The Greek historian Kritovoulos, described in graphic detail the fearful last hours of the Eastern Roman Empire. When read alongside the diary of the Venetian ship’s doctor, Nicolo Barbaro, who was present during the siege and recorded the terrible revenge exacted upon the remaining whites, an image of this epic period of history emerges: grim, brutal, and merciless. The following are their eyewitness accounts, edited together for brevity:

"On 28 May 1453, Mehmed began an inspection, on horseback, of his companies. It was late afternoon, with the hour of sunset already approaching, so that the sun was upon the besiegers’ backs and in the face of the enemy defenders, and the Sultan gave the orders for the trumpets to sound the attack. Each side began to attack the other with powerful volleys: arrows from the archers, stones from the slingers, iron and lead shot from the cannons and guns. As they neared each other, they also pelted one another mercilessly and furiously with axes and javelins. This continued through most of the night, both sides putting up a strong, brave fight. The other [Turkish] generals, meanwhile, also made an assault on the wall by land and with their ships, by sea, but the Greeks strongly repelled them. It was a brave defense: they prevailed in the fight and showed true virtue: for nothing that happened—not the hunger that oppressed them, not their lack of sleep, nor the continuous unstinting battle or the wounds, murders and deaths suffered by their dear ones before their very eyes—succeeded in turning them even slightly from their vigor and resolve.

"When Sultan Mehmed saw that the companies he had sent were getting the worst of the battle and making no significant progress, he decided the situation was to be endured no longer, and immediately sent in all the companies he had reserved for later, his best-armed, hardiest and bravest men. They were the thoroughbreds of his army: heavy infantry, archers, spear throwers and the company that formed his personal entourage consisting of the so-called Janissaries.

"And then the Turks brought up the huge cannon, which could throw a stone weighing five hundred and forty-five kilos, and sufficient arrows to fire against the whole length of the walls. An hour before daybreak the Turkish Lord fired his great cannon, and the missile fell on the defenses and razed them to the ground. Because of the great smoke made by the cannon, it was impossible to see anything. The Turks charged the walls, using the smoke for cover, and the Greeks and Venetians valiantly drove them out, and many of them, indeed almost all of them, were killed before they could enter the fortifications.

"At this time, because the Greeks had the best of this engagement and in truth believed themselves victorious over the pagans, we Christians were all greatly consoled. Having been driven back from the fortifications, the Turks fired their great cannon once more, and Mehmed again ordered the archers, slingers and gunmen to stand some way off and shoot at the front line of men on the stockade and the broken wall. The other heavy infantry and shield-bearers he ordered to cross the fosse and mount a violent assault on the stockade. They went at it with a great terrifying cry of rage and fury, like madmen, and, as they were youthful and strong, and full of courage, they never let up. But Giustinianni and the Byzantines were putting up a manful fight, holding back the Turkish surge. During the gunfire, however, Giustinianni was fatally injured by a shot from a firearm, which pierced right through his armor to his chest. He fell on the spot and was carried to his tent, in a bad state. All the men around him broke up in dismay at the event, and abandoned the stockade where they had been fighting.

"Sultan Mehmed, who happened to be fighting nearby, noticed that the stockade and place where the wall was broken were now unmanned, and he immediately cried out, ‘The city is ours!’ So saying he himself led the attack. The Turks poured into the city: the rest of the army followed with a violent surge then dispersed throughout the city. The Turks put the city to sword as they came, and everyone they found in their way they slashed with their scimitars, women and men, old and young, of every condition, and this slaughter continued from dawn until midday. They sought out the convents and all the nuns were taken to the ships and abused and dishonored by the Turks, and they were all sold at auction as slaves to be taken to Turkey, and similarly the young women were all dishonored and sold at auction; some preferred to throw themselves into wells and drown. These Turks loaded their ships with people and a great treasure. They had this custom: when they entered a house, they would at once raise a flag with their own device, and when other Turks saw such a flag raised, no other Turk would for the world enter that house but would go looking for a house that had no flag; it was the same with all the convents and churches. As I understand it, it seems there were some two hundred thousand of these flags on the houses of Constantinople. These flags flew above the houses for the whole of that day, and for all of that day the Turks made a great slaughter of Christians in the city.

"Blood flowed on the ground as though it were raining."