Bursa: The First Capital City of the Ottoman Empire

Orhan Bey, also referred as Orhan Ghazi (Turkish for "military man"), is the son of Muslim scholar Sheikh Edebali and Malhun Hatun. According to several historians, he was born to Bala Hatun, the daughter of Seljuk vizier mer Bey, or that Malhun Hatun and Bala Hatun were the same person. Orhan Ghazi was born in 1281, the same year that his grandfather Erturul Ghazi died. In Turkish, his name Orhan means "city judge."

Orhan Bey, who was brought up by his father as the future ruler, began with the establishment of a state. During his father's reign, he served as a commander in several decisive battles. He was the governor of Sultanönü, Eskişehir's modern-day central province. He married Holofira, the daughter of Yarhisar tekfur, when he was 17 years old (Byzantine lord or governor). Holofira became a Muslim and became the "Nilüfer."

Before dying of old age, Osman waged his final campaign against the Byzantines in the city of Bursa. Osman I enlarged his power south of the Marmara Sea, besieging the Byzantine city of Prusa (Bursa) in northwestern Asia Minor. The Ottomans had never besieged a city before, so the city fell after nine years due to a lack of experience in this type of warfare. On the 6th of April 1326, Osman's son Orhan Gazi led the final attack and delivered the news of Bursa's fall to his dying father.

Bursa became the first Ottoman capital, facilitating the formation of military, financial, and administrative institutions. In Bursa, for example, Ottoman coins were used for the first time. Between 1331 and 1338, Turkish forces conquered the other major Byzantine cities of Iznik, Izmit, and Üsküdar. Orhan's marriage to the Byzantine emperor's daughter gave him a free hand in the region, and in 1354, Orhan's son Süleyman landed at Gallipoli across the Dardanelles, a strait in northwest Turkey that connects the Sea of Mamara with the Agean Sea. Süleyman died in 1360, and his son Murad I (ca. 1326–1389) succeeded him as Sultan. During Murad's reign, Anatolia's peaceful acquisition of lands continued, as did war against Europe.

The Ottoman dynasty's founders, Osman and Orhan Gazi, were laid to rest in two ancient Byzantine structures that were drastically altered or completely rebuilt after the 1855 earthquake. Two Ottoman sultans from the seventeenth century were also buried in a Byzantine structure. Sultans Mustafa I and Brahim now rest in coffins in a baptistery converted into a tomb near Istanbul's Hagia Sophia.