The date of Sophia’s flight and of John’s third marriage is difficult to determine. The plainest reading of the contradictory chronicles is that the trouble occurred in the last year of Manuel’s reign and the flight took place a month after his death, but this is inconsistent with the express declaration that the old Emperor intervened in the dispute. Manuel died on 25th July 1425. For some years the ambition of the Turk, who had quickly recovered from the heavy blows dealt by Timour, had fully revived and had given him great anxiety. A young Sultan, Murad II., had succeeded to the throne, and Manuel had imprudently recognized a pretender to the succession. When the young Sultan vigorously took the field, hanged the pretender, and drew up under the walls of Constantinople, Manuel, now a feeble old man of seventy-five, left the direction of affairs to John, and retired to pursue that ardent study of the Scriptures which absorbed him in his later years. John abjectly apologized, but the angry Sultan ranged his machines against the walls and proceeded to batter them. He was drawn off for a time by the strategy of John, who had the Sultan’s brother conveyed to Brusa and set up as Sultan, but Murad returned more angry than ever, and one of the last earthly sounds to catch the ear of the aged Manuel was the roar of the first cannons that seem to have appeared at Constantinople. The diffusion of knowledge at the time may be gathered from the fact that one of the most learned of the chroniclers, in discussing these “bombards,” observes that he does not think they are of very ancient origin. Before the end of the siege Manuel was warned by an attack of apoplexy that his death was near. He donned the black robe, became plain Brother Matthew, and died two days--not two years, as Finlay says--afterwards, at the age of seventy-seven. Irene also then retired from the world and became the nun Hypomene, whom we shall later find endeavouring to settle the quarrels of her selfish children. She remained “mistress” (_despoine_) of the Empire and watched its slow decay with concern.