Mehmed I, also known as Celebi Mehmed, was the 5th sultan of the Ottoman dynasty. He was born in Bursa in 1389 and died in Edirne in 1421, he was buried in his mausoleum at the Green Tomb in Bursa. His father was Yildirim Bayezid and mother was Devlet Hatun.
After the defeat of sultan Yildirim Beyazit by Tamerlane in 1402, the Ottoman territories were divided among three of Bayezid's sons and thus Mehmed ruled in Amasya area. Mehmed fought with his brothers between 1402 - 1413 and after winning the battles he reunified the dismembered Ottoman territories, ruling the Empire until 1421. Therefore he's known as the "second founder" of the Ottoman Empire.
During his rule, Mehmet I faced several problems and risks such as his other brother, Mustafa, fighting against him. Then his nephew Orhan organizing a plot for overthroning Mehmet, and then rebellions against the throne. Between 1414-1420 he captured Karaman Principality and Candar Principality, captured some parts of the Balkans and fought against Venetians.
Reign:
After winning the Interregnum, Mehmed crowned himself sultan in the Thracian city of Edirne that lay in the European part of the empire (the area dividing the Anatolian and European sides of the empire, Constantinople and the surrounding region, was still held by the Byzantine Empire), becoming Mehmed I. He consolidated his power, made Edirne the most important of the dual capitals, and conquered parts of Albania, the Jandarid emirate, and the Armenian Kingdom of Cilicia from the Mamluks. Taking his many achievements into consideration, Mehmed is widely known as the "second founder" of the Ottoman Sultanate.
Soon after Mehmed began his reign, his brother Mustafa Çelebi, who had originally been captured along with their father Bayezid I during the Battle of Ankara and held captive in Samarkand, hiding in Anatolia during the Interregnum, reemerged and asked Mehmed to partition the empire with him. Mehmed refused and met Mustafa's forces in battle, easily defeating them. Mustafa escaped to the Byzantine city of Thessaloniki, but after an agreement with Mehmed, the Byzantine emperor Manuel II Palaiologos exiled Mustafa to the island of Lemnos.
However, Mehmed still faced some problems, first being the problem of his nephew Orhan, who Mehmed perceived as a threat to his rule, much like his late brothers had been. There was allegedly a plot involving him by Manuel II Palaiologos, who tried to use Orhan against Sultan Mehmed; however, the sultan found out about the plot and had Orhan blinded for betrayal, according to a common Byzantine practice.
Furthermore, as a result of the Battle of Ankara and other civil wars, the population of the empire had become unstable and traumatized. A very powerful social and religious movement arose in the empire and became disruptive. The movement was led by Sheikh Bedreddin (1359–1420), a famous Muslim Sufi and charismatic theologian. He was an eminent Ulema, born of a Greek mother and a Muslim father in Simavna (Kyprinos) southwest of Edirne (formerly Adrianople). Mehmed's brother Musa had made Bedreddin his "qadi of the army," or the supreme judge. Bedreddin created a populist religious movement in the Ottoman Sultanate, "subversive conclusions promoting the suppression of social differences between rich and poor as well as the barriers between different forms of monotheism."[10] Successfully developing a popular social revolution and syncretism of the various religions and sects of the empire, Bedreddin's movement began in the European side of the empire and underwent further expansion in western Anatolia.
In 1416, Sheikh Bedreddin started his rebellion against the throne. 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.
Death:
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.
Before his death, to secure passing the throne safely to his son Murad II, Mehmed blinded his nephew Orhan Çelebi (son of Süleyman), and decided to send his two sons Yusuf and Mahmud to be held as a hostage by Emperor Manuel II, hoping to ensure the continuing custody of his brother Mustafa.
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. Mehmed I also completed another mosque in Bursa, which his grandfather Murad I had commenced but which had been neglected during the reign of Bayezid. Mehmed founded in the vicinity of his own Green Mosque and mausoleum two other characteristic institutions, one a school and one a refectory for the poor, both of which he endowed with royal munificence.