The occupation of Adrianople and Philippopolis was as severe a blow to the Bulgarians as to the Byzantines. In spite of the fact, however, that Greek and Bulgarian had a common interest in driving the Osmanli from Thrace, or at the very least in checking his advance, there was no move made at this time for an alliance. On the contrary, even when the Osmanlis were engaged in the Thracian campaign, war arose between John V and Alexander. The Byzantines captured Anchiale, and tried desperately to take Mesembria by assault.[309] The Greek patriarch wrote to Czar Alexander, reminding him of the sacredness of harmony and the necessity of accord at that critical moment, but the letter was not backed by the good faith and good will of the Byzantine emperor. Neither John nor Alexander attempted to give assistance to the Serbian and Hungarian crusade that ended so disastrously on the banks of the Maritza. The conquest of Bulgaria up to the main Balkan range imposed itself upon Murad as a corollary to the Ottoman dominion in Thrace, and the undisturbed possession of Adrianople and Philippopolis. For the Bulgarians, through centuries of varying fortunes, had grown accustomed to fighting for the right to live in Thrace. Often had they been beaten back to the Balkans, and as often pressed forward again to the Ergene. To win and lose Adrianople and other Thracian cities was old history with them. They always came back. Between 1362 and 1365, Murad had experience with Bulgarian persistence and tenacity of purpose. They were masters again of Kirk Kilisse, Midia, Bunar Hissar, and Viza when Murad made his change of capital from Brusa to Adrianople. Yamboli had been strongly fortified by Alexander. Bulgaria seemed as formidable and as forbidding to Murad’s dream of empire as the emirates of Asia Minor. Fortune again favoured the Osmanlis. Czar Alexander died in 1365,[310] leaving three heirs. To John Sisman fell middle and southern Bulgaria from the Danube to the Rhodope Mountains and the Bulgarian pretensions in Thrace. Old Tirnovo was his capital. Stracimir inherited western Bulgaria, with Widin for capital, and the Bulgarian pretensions to the valley of the Vardar and western Macedonia. (The Bulgarian remnant of eastern Macedonia was in the hands of an independent Bulgarian prince, Constantine, whose stronghold was Kustendil.) Dobrotich became master of the Dobrudja and the upper Black Sea coast, where Bulgarian, Cuman and Alan lived together with hardly any distinguishing characteristics. The division of Bulgaria, at the moment when union was essential, proved fatal. The sons of Alexander never joined to face the common danger. So marked was the division of Alexander’s kingdom that thirty years after the conquest the conquered territories were known as ‘the three Bulgarias’.[311]