This was a rare opportunity for Manuel Paleologus: the thieves had fallen out, and the rightful owner might perchance come again to his own, if he played his cards well. The control of the Straits was of great importance to each of the Turkish pretenders, so much so, that Manuel was able to sell his aid to Suleiman for a heavy price. In order to keep Eesa from crossing the water, the holder of the European half of the Ottoman realm ceded to the Emperor Thessalonica, the lower valley of the Strymon, the coast of Thessaly, and all the seaports of the Black Sea from the mouth of the Bosphorus up to Varna. For a moment Manuel once more ruled what might in courtesy be called an empire, and so long as the Ottomans were occupied in civil war he contrived to retain his gains. The strife of the sons of Bayezid lasted ten years: Suleiman was slain by his brother Musa, Eesa by his brother Mohammed, and the two supplanters continued the war. By all Oriental analogies their empire ought to have fallen to pieces, for it is very much easier to build up a new state in the East than to keep together an old one which is breaking asunder. But Mohammed, the youngest of the sons of Bayezid, was a man of genius: he triumphed over the last of his brothers, and united all the remnants of the Ottoman realm that remained. Much had been lost to the Seljouk Emirs in Asia Minor, and to the Servians and Manuel Paleologus in Europe, but the rest was back in Mohammed’s hands by A.D. 1421. Manuel had very luckily cast in his lot with Mohammed during the later years of the Turkish civil war, and his ally let him enjoy the dominions he had recovered by his original treaty with Suleiman in 1403. Between 1402 and 1421, Europe had an unparalleled opportunity to rid herself of the Ottomans. Unfortunately it was not taken. Sigismund, king of Hungary, and at the same time Emperor, was the sovereign on whom the duty of leading the attack ought to have fallen. But Sigismund was now engaged in his great struggle with the Hussites in Bohemia. This wretched religious war directed the strength of Hungary northward when it was wanted in the south. Without such a power to back them the Servians, though they recovered their own liberty as a result of the battle of Angora, could do nothing towards driving the Turks from the Balkans. There was never any sympathy between Serb and Magyar, and save under the direct pressure of fear of a Moslem invasion they would not act together. The Hungarian kings had always laid claim to a suzerainty over the crown of Servia, and from time to time tried to convert their neighbours to Roman Catholicism by force of arms. Hence there was no love lost between them, and a crusade to expel the Turks was never concerted. [Illustration] Arabesque Design From A Byzantine MS. (_From "L’Art Byzantin." Par Charles Bayet. Paris, Quantin, 1883._)