Of the troubles which beset the ambassadors and how they were redressed more shall be said hereafter. Osman's six years of rule were disturbed by sterner men. The Janissaries again showed that their power was greater than that of the Sultan. Osman decimated them in war, and executed many who drank wine; but they were too strong for him, dragged the unhappy Mustafa again from prison, and again declared him to be the ruling Sultan. The Kafess (cage), the splendid building in the grounds of the old Seraglio, which even now may not be approached, which had so long held him prisoner, has memories of no stranger history than his. When he was dragged forth he trembled before his nephew, and threw himself at his feet. Osman taunted the Janissaries with the weakness of the ruler they preferred to himself; but it was not weakness that the Janissaries feared. Osman was dragged to the Seven Towers, and there, after a desperate struggle, he was strangled in a dungeon. Within a few months the idiot Mustafa was again deposed and sent back to the Kafess, where soon afterwards the bowstring ended his miserable life. For the few months of his nominal reign he was entirely in the hands of the soldiery; minister after minister was given up to them, and ended his life by the bowstring or on the fatal tree. The Janissaries held Constantinople in terror, and raised and deposed a Sultan as easily as a minister. Murad IV., still a child, the surviving son of Ahmed, was made Sultan in 1623. In him the Turks had again a masterful and determined ruler. His mother the Valideh, and his Vizier Hafiz, made the first years of his reign distinguished if not glorious. Till 1632 he trained himself in all military exercises; he rode, he drew the bow with the best of the Janissaries. Then came the revolt of the Sipahis and Janissaries, which gave him his opportunity. Constantinople was for many days in the hands of the military mob, reinforced by disaffected troops who had returned from Persia. They assembled in the Atmeidan (the old Hippodrome); thence they went to the Seraglio and demanded the "seventeen heads" of the Sultan's chief advisers and friends. For some days Murad held out. He summoned the Vizier, Hafiz, who rode through the crowd, past the barracks of the Janissaries, in at the Orta Kapou, after dismounting, the stones of the mob falling round him as he disappeared. Murad ordered him to escape to Juntan. Within a few hours the Sultan was compelled to come forth to the people and hold Divan. They demanded the seventeen--the "vizier, the aga of the Janissaries, the deftarder, and even a boy, because he was liked by the Sultan." "Give us the heads," they cried. "Give the men up to us, or it shall be the worse for thee."