Battle of Nicopolis
In 1388, the Ottomans invaded Sratsimir's lands and forced him to become their vassal. In 1396, he joined an anti-Ottoman crusade led by the King of Hungary, Sigismund, placing his resources at the crusaders' disposal. The crusade ended in the disastrous Battle of Nicopolis at Nikopol, Bulgaria, with the Ottomans capturing most of Sratsimir's domains shortly thereafter, in 1397.