But though the provinces of the corrupt and effete Byzantine Empire were falling into the hands of the Turks, the Slavs were still unsubdued.  Lazar the Serb threw down the gauntlet to Murad.  On the memorable field of Kossovo, in 1389, the opposing forces met—­Murad supported by his Asiatic and European vassals and allies, and Lazar with his formidable army of Serbs, Bosnians, Albanians, Poles, Magyars, and Vlachs.  Few battles in the world have produced such a deep and lasting impression as this battle of Kossovo, in which the Christian nations after long and stubborn resistance were vanquished by the Moslems.  The Servians still sing ballads which cast a halo of pathetic romance round their great disaster.  And after more than five centuries the Montenegrins continue to wear black on their caps in mourning for that fatal day.

In the next two centuries the Ottoman Empire moved on toward the zenith of its glory.  Mohammed II conquered Constantinople in 1453.  And in 1529 Suleyman the Magnificent was at the gates of Vienna.  Suleyman’s reign forms the climax of Turkish history.  The Turks had become a central European power occupying Hungary and menacing Austria.  Suleyman’s dominions extended from Mecca to Buda-Pesth and from Bagdad to Algiers.  He commanded the Mediterranean, the Euxine, and the Red Sea, and his navies threatened the coasts of India and Spain.

But the conquests of the Turks were purely military.  They did nothing for their subjects, whom they treated with contempt, and they wanted nothing from them but tribute and plunder.  As the Turks were always numerically inferior to the aggregate number of the peoples under their sway, their one standing policy was to keep them divided—­divide et impera.  To fan racial and religious differences among their subjects was to perpetuate the rule of the masters.  The whole task of government, as the Turks conceived it, was to collect tribute from the conquered and keep them in subjection by playing off their differences against one another.

But a deterioration of Turkish rulers set in soon after the time of Suleyman with a corresponding decline in the character and efficiency of the army.  And the growth of Russia and the reassertion of Hungary, Poland, and Austria were fatal to the maintenance of an alien and detested empire founded on military domination alone.  By the end of the seventeenth century the Turks had been driven out of Austria, Hungary, Transylvania, and Podolia, and the northern boundaries of their Empire were fixed by the Carpathians, the Danube, and the Save.  How marked and rapid was the further decline of the Ottoman Empire may be inferred from the fact that twice in the eighteenth century Austria and Russia discussed the project of dividing it between them.  But the inevitable disintegration of the Turkish dominion was not to inure to the glorification of any of the Great Powers, though Russia certainly contributed to the weakening of the common enemy.