before the Black Death, and continued long after, and plague is only one of the many factors in the economic developments of the fourteenth century. Likewise the symptoms of economic 'crisis' are not always what they seem to be. True, many ports on the Mediterranean showed a dramatic drop in through trade. But as some towns, industries, and trade routes declined, others sprang up. The Mediterranean saw in the fourteenth century not uniform crisis but rather the beginnings of shifts in emphasis, of which more were to follow in the fifteenth.
One of these shifts was started by another 'plague from the east'. On its eastern flank thirteenth-century Byzantium had had to contend with a number of Turkish tribes. The early fourteenth century saw the rise to prominence of one of these, the Osmanlis or Ottomans, named after their first leader, Osman. The rise of the Ottomans was very rapid. When in 1302 Osman defeated the Byzantines in Bithynia he seemed just one of several tribal leaders. In 1326 his son Orchan captured Bursa, just across the sea of Marmora from Constantinople itself, and in 1329 he defeated the Byzantine forces twice near Nicomedia. In 1331 Nicaea fell, and in 1337 Nicomedia. In a short time the Byzantine Empire had lost all its possessions in Asia Minor, and by the terms of a treaty made with Orchan in 1333 even had to pay him an annual tribute. But that was only a first taste of Ottoman might. By the time they had captured Gallipoli ( 1354) they were already involved in military enterprises in Europe, often in alliance with Byzantium. Next, all this was rapidly consolidated by Orchan's successor Murad I. Adrianople was taken, and the Turkish court set up there. There was victory over the Serbs at the River Marica in 1371, and in 1387 the second largest Byzantine city, Thessalonica, fell. Murad was killed in battle at Kossovo in 1389, but the Serbs themselves were defeated, and with that the empire was completely encircled. In 1394 Bajezid I turned to Constantinople itself.
From the capture of Gallipoli onwards the prevention of engulfment by the Ottomans had been the Byzantine emperor's dominant concern. The Emperor John V became the first of a series of emperors to humiliate themselves by making journeys
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