It is a vulgar error to suppose that the Osmanlis set out for Europe, in the spirit of Arab apostles, to force their creed and dominion on all the world.  Both in Asia and Europe, from first to last, their expeditions and conquests have been inspired palpably by motives similar to those active among the Christian powers, namely, desire for political security and the command of commercial areas.  Such wars as the Ottoman sultans, once they were established at Constantinople, did wage again and again with knightly orders or with Italian republics would have been undertaken, and fought with the same persistence, by any Greek emperor who felt himself strong enough.  Even the Asiatic campaigns, which Selim I and some of his successors, down to the end of the seventeenth century, would undertake, were planned and carried out from similar motives.  Their object was to secure the eastern basin of the Mediterranean by the establishment of some strong frontier against Iran, out of which had come more than once forces threatening the destruction of Ottoman power.  It does not, of course, in any respect disprove their purpose that, in the event, this object was never attained, and that an unsatisfactory Turco-Persian border still illustrates at this day the failures of Selim I and Mohammed IV.

By the opening of the fifteenth century, when, all unlooked for, a most terrible Tartar storm was about to break upon western Asia, the Osmanli realm had grown considerably, not only in Europe by conquest, but also in Asia by the peaceful effect of marriages and heritages.  Indeed it now comprised scarcely less of the Anatolian peninsula than the last Seljuks had held, that is to say, the whole of the north as far as the Halys river beyond Angora, the central plateau to beyond Konia, and all the western coast-lands.  The only emirs not tributary were those of Karamania, Cappadocia, and Pontus, that is of the southern and eastern fringes; and one detached fragment of Greek power survived in the last-named country, the kingdom of Trebizond.  As for Europe, it had become the main scene of Osmanli operations, and now contained the administrative capital, Adrianople, though Brusu kept a sentimental primacy.  Sultan Murad, who some years after his succession in 1359 had definitely transferred the centre of political gravity to Thrace, was nevertheless carried to the Bithynian capital for burial, Bulgaria, Serbia, and districts of both Bosnia and Macedonia were now integral parts of an empire which had come to number at least as many Christian as Moslem subjects, and to depend as much on the first as on the last.  Not only had the professional Osmanli soldiery, the Janissaries, continued to be recruited from the children of native Christian races, but contingents of adult native warriors, who still professed Christianity, had been invited or had offered themselves to fight Osmanli battles—­even those waged against men of the True Faith in Asia.  A considerable body of Christian Serbs had stood up in Murad’s line at the battle of Konia in 1381, before the treachery of another body of the same race gave him the victory eight years later at Kosovo.  So little did the Osmanli state model itself on the earlier caliphial empires and so naturally did it lean towards the Roman or Byzantine imperial type.