 After a four-year struggle, he was finally captured by Mehmed's grand vizier Bayezid Pasha and hanged in the city of Serres, a city in modern-day Greece, in 1420.The reign of Mehmed I as sultan of the re-united empire lasted only eight years before his death, but he had also been the most powerful brother contending for the throne and "de facto" ruler of most of the empire for nearly the whole preceding period of 11 years of the Ottoman Interregnum that passed between his father's captivity at Ankara and his own final victory over his brother Musa Çelebi at the Battle of Çamurlu.He was buried in Bursa, in a mausoleum erected by himself near the celebrated mosque which he built there, and which, because of its decorations of green glazed tiles, is called the Green Mosque.