Which Ottoman sultan was known as 'Yıldırım' (the Thunderbolt)?

Bayezid I was the Ottoman sultan known as Yıldırım, meaning “the Thunderbolt.” The nickname reflected his speed, aggressive campaigning, and reputation as a formidable military commander.

Bayezid ruled from 1389 to 1402, succeeding his father, Murad I, after the Battle of Kosovo. During his reign, he expanded Ottoman authority across much of Anatolia and the Balkans. He defeated a major European crusading army at the Battle of Nicopolis in 1396 and repeatedly pressured Constantinople through lengthy campaigns and sieges.

His rapid expansion eventually brought him into conflict with Timur, the Turco-Mongol ruler of Central Asia. At the Battle of Ankara in 1402, Timur defeated and captured Bayezid. The sultan died in captivity in 1403, and the defeat plunged the Ottoman dynasty into a succession struggle known as the Ottoman Interregnum.

The title can be confused with other powerful Ottoman rulers, particularly Mehmed II or Murad I, who also achieved major conquests. However, Yıldırım is specifically associated with Bayezid I. His reign helped transform the Ottoman state into a major regional empire, even though its expansion temporarily fractured after his defeat.