Agios Nikolaos (Tekfur Of Inegol)
Agios Nikolaios (Old Anatolian Turkish: Aya Nikola) was the Tekfur of İnegöl.
Battle of Mount Armenia
Agios Nikolaios perceived Turkish infiltration in Bithynia as a violation of Byzantine sovereignty. Hence, he was determined to reverse the encroachment of the Turks upon Bithynia and started plundering Kayi markets. When Osman Bey moved towards İnegöl seeking retribution, he was ambushed at the Battle of Mount Armenia by Nikola and his retinue. The Kayi were vastly outnumbered so sustained heavy casualties. Even Bayhoça, son of his brother Savcı Bey and a renowned warrior, was killed. The Turkish cavalry managed to escape with their sword high to break the Byzantine line. There was no winner to this battle as both sides had to retreat back into their own lands and regroup. Osman Bey sought to avenge this attack by besieging Kulaca Hisar.
Siege of Kulaca Hisar
As revenge for all those slain on the mountain, Osman attacked the Byzantine-held Kulacahisar Castle, which is 5 kilometers away from Inegöl and located on the outskirts of Emirdağ to protect the city. A few men snuck into the fortress disguised as Romans, neutralized the guards and opened the gates. As a result of a night raid with a force of 2,000, the castle was captured by the Turks. This is the first castle conquered in the history of the Ottoman Empire. Since the captured Christian people of Kulaca Hisar accepted the rule of Osman Bey, they were not harmed.
Battle of Domaniç
When the Ottomans conquered Kulacahisar in 1285, the local tekfurs of Bithynia gathered for an emergency meeting. Therefore, they sent a message to the tekfur of Karacahisar:
Displeased with the growing strength of the Kayıs, especially their capture of Kulacahisar, the tekfur of İnegöl, Aya Nikola, continued to incite his neighbor, the tekfur of Karacahisar, against the Kayıs. This led to an alliance between the İnegöl and Karacahisar tekfurs. Shortly afterward, the two tekfurs launched an offensive against the Kayıs. Aya Nikola, in alliance with the Karacahisar tekfur, gathered a large army and appointed Kalanoz, the brother of the Karacahisar tekfur, as their commander.
The combined Byzantine army and the forces of the Kayıs set out from İnegöl and clashed at Domaniç İkizce. Ultimately, the combined Byzantine army was routed. Although the Kayıs emerged victorious in the battle, Osman Bey's elder brother, Saru Batu Savcı Bey, was killed. On the enemy side, Kalanoz, the brother of the Karacahisar tekfur and commander of the army, and many others were killed, while the rest fled.