Amongst ali the Beyliks (provinces) founded with the downfall of the Seljuk Empire, the Ottoman Beylik rapidly developed, assimilated the surrounding provinces and grew in strength and territory. in 1299, inegöl, Bilecik and Yenişehir were added to the Beylik's territories.
The feudal lord of Bursa, Atranos, reacted with suspicion to the conquests of Osman Gazi, and, supported by the feudal lords of Kestel and Kite and help from Byzantium, met the Ottoman army in Koyunhisar. This battle of 1301 was won by the forces of Osman Bey. In the year 1307, following the collective attitude of the feudal lords, the Ottoman army, under the command of Osman Gazi, besieged the city of Bursa. During the long siege of the city, Osman Bey became ill, and, passing the command of the siege to his son Orhan Bey, left for Yenişehir.
In the year 1321, Mudanya, Gemlik and Orhaneli were assimilated into Ottoman territory and the Bursa siege narrowed down considerably. On the April 6th, 1326, Orhan Bey took possession of the city. The surrender of Bursa was a turning point for the Ottoman Beylik. Following this success, Ottoman units were dispatched to Nicaea (İznik), considered to be an important Byzantine fort. Byzantine Emperor Andronicus III fınally gave up the struggle with the defeat of his armies at Pelecano. As a result of Orhan Gazi's stubborn siege, Nicaea was handed over in 1331, and the capital for the became fıve years. In 1334, Cius (Gemlik) was added to the Ottoman territory. The capital was transferred to Bursa in 1335, and important construction work began. Orhan Gazi carried the city out of the boundaries of the fort and founded the Orhan Gazi mosque complex. Turcoman families were brought to the city from Central Anatolia, whereas the population increased in relation with the minorities. When Orhan Gazi died in the year 1360, he was succeeded by Murat I Hüdavendigâr. Concentrating his activities on Rumelia, in 1366 this sultan had the capital transferred to Edirne.
In 1389, Yıldırım Bayezıd succeeded Murat I, who was murdered during the great victory achieved against the Crusader armies in Kosovo. Yıldırım Bayezıd's first task was to smother the revolts in Anatolia. He added the Beyliks of Aydın, Saruhan, Menteşe and Karaman to his country. In 1396, he besieged Istanbul and was victorious in the Niğbolu war. But when he lost the battle against Tamerlane in the valley of Ankara in 1402, Bursa was captured by Timur. Not being able to accept this defeat, Yıldırım Bayezıd commited suicide. Tamerlane divided the territory into Beyliks again, and thus initiated a long period of civil war in the once unified country.
Of Bayezıd's sons, Mehmet Çelebi proclaimed his independence in Amasya, Isa Çelebi in Balıkesir and the environs of Bursa, and Süleyman Çelebi in Thrace.
Musa Çelebi, captured by Timur during the Battle of Ankara, was released upon the death of his father and handed over his corpse. Musa Çelebi travelled to Bursa, banished Isa Çelebi to Balıkesir and proclaimed his independence.
Nevertheless, Isa Çelebi rapidly regained confidence and retook Bursa under his control. These conflicts were messengers to further bloody battles between the dead sultan's sons.
Çelebi Mehmet, who was in Amasya at the time, tried to reach an agreement with his brother Isa Çelebi. When Isa Çelebi violently turned him down, the two brother's armies met at Uluabat. Isa Çelebi was defeated and sought shelter within the Byzantine Empire. Süleyman Çelebi, wanting to profıt from the situation, agreed with the Byzantine emperor, and called his brother to his side. Süleyman gave his brother strong units and sent him towards Bursa. As Isa Çelebi was attempting to conquer the city deceitfully, he was hindered at the last minute by Çelebi Mehmet, who dispersed his army. Isa Çelebi was killed in Eskişehir. He was buried in his father's tomb.
Süleyman Çelebi, who considered the strength of Mehmet Çelebi in Anatolia threatening, crossed over to Anatolia with his armies and conquered Bursa and Ankara he whereby, later settled down in Bursa. After completing his military preparations, Çelebi Mehmet advanced towards Bursa, but the two armies could not face abattle.
Çelebi Mehmet was extremely uneasy about his brother's presence in Anatolia. Wanting to solve the situation without any bloodshed, he chose to agree with his brother Musa Çelebi. He sent Musa Çelebi over to Rumelia with his units. As a response to Musa's strengthening position in Rumelia, Süleyman Çelebi left Bursa for Rumelia. Having waited for this moment patiently, Çelebi Mehmet was then able to reattach Ankara and Bursa to his territory. in Rumelia, Süleyman Çelebi defeated Musa Çelebi. However, Musa Çelebi rapidly regained control of the situation, and met Süleyman's armies in Sofia and this time he was victorious. His brother died in the battlefield, his corpse was buried in the Murat I tomb in Bursa. Although Musa Çelebi had passed over to Rumelia under an agreement, gaining confidence from his victory, he proclaimed his independence. Mehmet Çelebi then defeated Musa Çelebi with a strong army, and finally ended the battle raging among the siblings and proceeded to reunify the Ottoman state. On the other hand, taking advantage of the absence of Çelebi Mehmet while he was in Rumelia fıghting Musa Çelebi, Karamanoğlu Mehmet Bey advanced towards Bursa, but was not able to overcome the successful defense of Hacı İvaz Pasha. He attempted several tricks, including setting fire to neighbourhoods and mosques outside the fortification walls and waiting for the population to come out and fight the fire to attack them. Ali his tricks were discovered, and he was unsuccessful in his attempts. in the meantime, having received news of Musa Çelebi's death and Çelebi Mehmet's return to Bursa, he hastily drew back. Upon his success, Çelebi Mehmet commenced important construction activities in Bursa.
Upon his death at the age of 34 in 1421 in Edirne,Murat II became sultan.Following the death of Tamerlane in 1405,Yıldırım Bayezıd's son Mustafa was released from captivity, travelled to Anatolia, and from there, with the support of Byzantium, crossed over to Rumelia. When the Ottoman leaders and military forces of Rumelia joined forces with him, the Ottoman territory was once again divided. At the same time,various unrests were unfolding in Anatolia. Murat II sent an army under the command of vizier Bayezıd Pasha to fight Mustafa, but Bayezıd Pasha was captured when part of his army deserted and joined the enemy lines.Gaining confidence, Prince Mustafa crossed over to Anatolia with a strong army and advanced towards Bursa. The two armies met in the vicinity of Lake Uluabat. But when an important part of Mustafa's supporters deserted him upon the negotiations of Ottoman rulers, he prefered to escape. He was followed, captured and killed.
At the same time Murat II's brother Mustafa was also waiting for an appropriate instant to attack. While Murat II was busy fighting Prince Mustafa, he assembled an army and advanced towards Bursa. Failing to conquer the city, he withdrew to Nicaea, but he was captured in 1423. Being a quiet and peaceful person by character, Murat II left his throne to his son Mehmet II three times. Alas, because of various dangers, he had to reascend the throne each time. During this period, he resided in Bursa. Upon his death in 1451, he was buried in his tomb in Muradiye. After the conquest of Istanbul by Mehmet II the conqueror, Bursa's importance in history will greatly diminish.
Compared to other cities, Bursa was subject to very important developments during the fırst 200 years of the Ottoman Empire. The city was decorated with many architectural works of art, and became the cultural centre of the scientific world through renouned madrasas.
The city gained economic strength from it's lively trade.
When Murat I transferred the capital to Edirne, he took with him the economic and cultural resources, thus condemning Bursa to be a city of secondary importance. Later on, with the conquest of Istanbul, Bursa would lose further importance. in addition to the worsening economic situation of the Ottoman Empire at the end o the sixteenth century and the degeneration of the Bursa Madrasa youth, the destruction of agricultural land in and around Bursa due to numerous locust plagues, endengered bringing an starvation, which, in turn, encouraged banditry and crime. These developments resulted in the Celali Rebellions, Bursa and environs were under the command of the rebel leader Kalenderoğlu. Nevertheless, in 1606 the incident was solved successfully suppressed by the Ottoman Empire.
In the meantime, the rebellion of Abaza Hasan Pasha in Konya grew to frightening dimensions, and became a strong pillaging force. The forces advancing westwards captured Bursa. The people of Bursa refusing to side with them were banished to Edirne. But Köprülü Mehmet Pasha soon put an end to this rebellion, captured the leader and ordered to kill him.
The progressively weakening regional administrations and incidents of brigandage in the years following 1753 caused the population of Anatolia to flee towards big cities such as Bursa Istanbul and Edirne, and engendered new problems in these cities in the nineteenth century, Bursa was again a favored city of the Ottoman Empire.
Economically, the city grew considerably stronger. Sultan Abdulmecit visited the city of Bursa in 1844. In the meantime various Construction projects were commenced in Bursa. But in 1855, a violent earthquake turned a significant part of the city to rubble, and the subsequent fire to ash.
