 In September 1345, after a long siege, Serres fell to Dušan. The Serbian ruler, who by now controlled about half of the pre-1341 Byzantine realm, was spurred by this success to lay his own claim on the Byzantine throne. Consequently, on Easter Sunday, 16 April 1346, he was crowned "Emperor of the Serbs and the Romans" in Skopje, thereby founding the Serbian Empire. This development prompted Kantakouzenos, who had only been acclaimed Emperor in 1341, to have himself formally crowned in a ceremony held at Adrianople on 21 May, presided over by the Patriarch of Jerusalem, Lazaros. Lazaros then convened a synod of bishops to excommunicate the Patriarch of Constantinople, John Kalekas. Not long afterwards, Kantakouzenos' ties with his new ally Orhan were cemented through the marriage of his daughter Theodora Kantakouzene to the Ottoman emir at an elaborate ceremony in Selymbria.
