The first Turkish invasion of Europe occurred in 1341, when Orhan crossed the Bosporos to intervene in the civil wars of the Eastern Empire. Several minor raids followed, while the Emir Orchan (1326-1360), who may be regarded as the founder of the Ottoman power, established his capital at Brusa. In 1358 his son Suleiman again invaded Europe, and the Chersonnese was soon filled with colonies of Ottomans.[288] In 1359 Gallipoli, “the key of Europe,” was occupied and rebuilt as a Turkish town. In 1360 both Orchan and his son Suleiman died, and his second son Murad succeeded to the throne. The latter in the following year captured Adrianople, which henceforward was to be the seat of the Turkish Government, and the headquarters for the attacks on the Greek Empire, the Serbs, and the Bulgarians. In 1370 a Turkish army of 70,000 men under Murad spread into Macedonia, but was driven back by the Serbs under King Vukašin and his brother Ulješa. He advanced again the following year, and encountered the Serbs at Černomen,[289] on the right bank of the Marica, a day’s march from Adrianople. The Serbs won in the first instance, but during the night the Turks rallied, and inflicted a terrible defeat on them. Vukašin and his brother fell with the flower of the Servian chivalry.[290] The Turks now overran Macedonia and Servia, and forced Marko Kraljević, Vukašin’s eldest son, and other Slave princes to pay tribute to them. The vassals who had hitherto obeyed Vukašin now rebelled against his son, and the Servian Empire was definitely broken up, while the Turks became ever more powerful.