III
The Byzantine Empire did not recover, even temporarily, from the effect of Murad’s first campaign in Europe. The fall of Demotika and Adrianople, followed so closely by that of Philippopolis, removed within eighteen months the last hope of retrieving the fortunes of the empire. There were still many places remaining to the Byzantines in Thrace. But the surrender of the fortresses in the valleys of the Ergene and the Maritza had destroyed the military prestige of the Byzantines, and foreshadowed the speedy subjugation of the whole country. The loss of the revenues of Thrace and of the great plain south of the main Balkan range reduced the imperial treasury to dependence upon the port duties and city taxes of Salonika and Constantinople. For ninety years the shadow of the empire remained. But whatever power, whatever influence was left to the successors of Constantine, it was rather in western Europe than in the Balkan peninsula. The impress of one thousand and thirty years of continuous existence from the renaming of old Byzantium to the fall of Adrianople was too deep to vanish in a few years. The decay had been going on for centuries. The final extinction would of necessity take several generations.
The complete abasement of the Byzantines is revealed in the treaty that John V Palacologos was compelled to conclude with Murad shortly after the capture of Philippopolis. In the fall of 1362 or the spring of 1363, John bound himself to refrain from any attempt to win back what he had lost in Thrace, either by a separate attack or by joining the Serbians or other enemies of the Osmanlis. In addition he promised to aid Murad against his Anatolian enemies, the Turkish emirs.[268]
After this treaty was signed, Murad withdrew to Brusa in order to provide for the organization of the new possessions that had come to him by a successful expedition against Angora. His letters, written at this time to announce to his Anatolian neighbours and to the Moslem princes of Asia the victories in Thrace, show clearly that he did not yet feel himself strong enough to assume the position of overlord to the other great emirs of Asia Minor. While he was in Brusa, in the spring of 1363, an event happened which led Murad to make the momentous decision that shaped the destinies of the Ottoman Empire. The first coalition against the Osmanlis was formed in Europe.