Lopadion (modern Uluabat, Bursa) was a fortress in northwestern Asia Minor on the Rhyndakos River (Çapraz Stream), about 20 km south of the Sea of Marmara. Lopadion was important for its bridge that carried the main highway eastward from Kyzikos. It first appears as the site of a xenodocheion in the letters of Theodore of Stoudios. A strategic point and substantial market town, Lopadion was the scene of fighting between Alexios I Komnenos and the Turks; it rose to prominence in 1130, when John II Komnenos built a powerful fortress that became the base for his campaigns in Asia Minor. The French and German contingents of the Second Crusade met there in 1144; the Latins held it in 1204 and 1211-1220. In the early 14th century, it was a frontier post against the Ottomans; Orhan took it in 1335. Lopadion, not previously attested as a bishopric, became an archbishopric in the early 12th century. The surviving walls are the work of John II Komnenos.
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Oxford Dictionary of Byzantium