Despite strong resistance, the Ottomans seized a number of important towns and fortresses in 1388, and five years later they captured Tarnovo after a three-month siege. Ivan Shishman died in 1395 when the Ottomans, led by Bayezid I, took his last fortress Nikopol. In 1396, Ivan Sratsimir joined the Crusade of the Hungarian king Sigismund, but after the Christian army was defeated in the battle of Nicopolis the Ottomans immediately marched on Vidin and seized it, bringing an end to the medieval Bulgarian state. Resistance continued under Constantine and Fruzhin until 1422. The former was referred to by king Sigismund as the "distinguished Constantine, glorious Emperor of Bulgaria".