In the early days of the siege, or possibly just before it began, Mahomet attacked all the Greek villages which had escaped the savagery of the troops in their march to the capital. Some kind of fortification existed at Therapia on the Bosporus. This was attacked by the Janissaries. Many of its defenders were slain, and the remainder, consisting of forty men, seeing that resistance was useless, surrendered. They were all impaled. Another fortification, known as Studium, was similarly attacked. Its thirty-six survivors were taken to a spot near the wall, so that they might be seen by the citizens, and were there impaled. At the island of Prinkipo the round tower still exists which had been a place of refuge for the protection of the inmates of the adjacent monastery. The monastery itself had been used as a place of retreat for the princely members of the imperial family, and had thus given its name to the Princes Islands. Baltoglu was sent with a portion of the fleet to attack it. Although he had cannon with him, he was unable to destroy its solid Byzantine masonry, and the thirty well-armed defenders refused to surrender. His crews thereupon cut down the neighbouring brushwood, and with this, with straw, and with sulphur, he smoked out the garrison. While some perished in the flames, others broke through the burning materials and surrendered. The admiral killed those who were armed, and sold into slavery the other inhabitants of the island.[281] CHAPTER XII _THE SIEGE_ INVESTMENT BY TURKS; FIRST ASSAULT FAILS; ATTEMPT TO FORCE BOOM; ATTEMPT TO CAPTURE SHIPS BRINGING AID; GALLANT FIGHT AND DEFEAT OF TURKISH FLEET; TURKISH ADMIRAL DEGRADED; TRANSPORT OF TURKISH SHIPS ACROSS PERA INTO THE GOLDEN HORN. We have now arrived at the last act of the tragedy of Constantinople. The Queen City is cut off from the outside world. Its small fleet dare not attempt to pass outside the boom which excludes the Turkish fleet. An overwhelming force of ships had been collected to keep out supplies of men or provisions. Before its landward walls is an army of one hundred and fifty thousand fighting men and a crowd perhaps equally numerous awaiting their chance of plundering the remnant of that wealth which had once been contained in the great storehouse of the Western world. [Sidenote: Mahomet’s army before the walls on April 7, 1453.]