Bayezid I, also known as Bayezid the Thunderbolt, was the sultan of the Ottoman Empire from 1389 to 1402. He adopted the title of Sultan-i Rûm, Rûm being the Arabic name for the Eastern Roman Empire. In 1394, Bayezid unsuccessfully besieged Constantinople. Two years later, he defeated the crusaders at the Battle of Nicopolis in what is now Bulgaria in 1396. Bayezid vanquished all the Anatolian beyliks and proceeded to conquer and vassalize the entirety of Anatolia. In 1402, he once more besieged Constantinople, appearing to find success, but he ultimately withdrew due to the invasion of the Turco-Mongol conqueror Timur. Bayezid was defeated and captured by Timur at the Battle of Ankara in 1402 and died in captivity in March 1403, which triggered the Ottoman Interregnum between his sons.