The leading commanders such as Akcakoca, Karamursel, Abdurrahman Ghazi received the qualifications Kandira, Aydos and Semendire . Thus, the borders of the Ottoman Empire extended to the Black Sea and the Bosphorus. Since the age of 15, Orhan Bey, who has been living with wars and victories, has made a military arrangement and founded an army in 1328, giving the name "Yaya". The Ottomans taking the castles of the peninsula of Kocaeli and coming to the Bosphorus. The Byzantine Empire was alarmed. Emperor III.Andronikos prepared an army to take back the conquered castles and save the besieged Iznik. Orhan Bey stepped into action against the Byzantines leaving some force in Iznik. Two armies met at Palekonon. The Byzantine army was defeated at the Battle of Palekonon (1329). After this important victory, Orhan Ghazi continued to siege Iznik. He informed that the commander of the Iznik, who cut off his hope from the Byzantine Empire, would surrender under certain conditions. Orhan has promised to comply with the alleged conditions and to treat the public well. Iznik, one of the most important cities of Christianity, thus entered into Turkish domination in 1330. Orhan Bey continued the conquests and added Tarakli, Goynuk and Mudurnu in 1331 and Gemlik in 1333 to the Ottoman lands. Orhan Bey conquered Izmit and its surroundings (Koyunhisar, Hereke, Yalova, Armutlu), an important commercial center in 1337. The administration of this place was given to his son Suleyman Pasha. In 1342, when the Kirmasti, Mihalic and Ulubat settlements belonging to the Greeks near Balikesir were conquered, they were bordered by the Karesi sons's Principality. Took advantage of fights of the throne, Orhan Ghazi seized the lands of Karesi sons's (1345). Haci Ilbey and Evrenos Ghazi from the sons of Karesi entered the service of the Ottoman State and the fleet of the Karesi participated in the Ottoman State. Marmara Islands, Uskudar and Kadıkoy were conquered (1352). In 1354, Gerede was seized and Ankara was conquered for the first time. Orhan Bey transferred the state lands, which he received from his father Osman Bey in 16000 km², to his son Murat Hudavendigar in 95000 km².
