Years of insulting letters had passed between Timur and Bayezid. Both rulers insulted each other in their own way while Timur preferred to undermine Bayezid's position as a ruler and play down the significance of his military successes. Finally, Timur invaded Anatolia and defeated Bayezid in the Battle of Ankara on 20 July 1402. Bayezid was captured in battle and subsequently died in captivity, initiating the twelve-year Ottoman Interregnum period. Timur's stated motivation for attacking Bayezid and the Ottoman Empire was the restoration of Seljuq authority. Timur saw the Seljuks as the rightful rulers of Anatolia as they had been granted rule by Mongol conquerors, illustrating again Timur's interest with Genghizid legitimacy.