Britannica Sources used in this answer

Which Byzantine cities in northwestern Anatolia did Orhan capture?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

This map shows the territorial expansion of the Ottoman Empire from 1300 to its greatest extent in 1683-99, highlighting different periods under rulers such as Mehmed II, Selim I, and Süleyman the Magnificent, and marking key cities, seas, and geographical boundaries in Europe, North Africa, and the Middle East. — Ottoman Empire Map showing the expansion of the Ottoman Empire from about 1300 to 1700. The empire reached its greatest extent between 1683 and 1699.

During his reign, Orhan captured several key Byzantine cities in northwestern Anatolia, which were instrumental in transforming the Ottoman principality into a powerful state. These conquests included:12

Bursa (formerly Brusa): Captured in 1324 (though some sources cite 1326), this city became the first Ottoman capital and a major Islamic center.12
Nicaea (modern İznik): Captured in 1331.12
Nicomedia (modern İzmit): Captured in 1337.12
Üsküdar: Captured in 1338.2

These victories allowed Orhan to consolidate control over the region and provided the administrative and military foundation for further expansion into the Balkans.12