The  Battle of Kossovo was fought in 1389 at Kosovo Polje in present Yugoslavia, between the armies of the Serbian prince Lazar and the Turkish forces of the Ottoman sultan Murad I, ending in a Turkish victory; the collapse of Serbia; and the encirclement of the Byzantine Empire by Turkish armies.

At first, victory appeared to be on the side of the Serbs, when the Sultan was killed by a Serbian noble who made his way into the Turkish camp on pretext of being a deserter. The confusion that followed was quickled ended by Bayezid, the Sultan's son, who inflicted a crushing defeat on the Serbs.

Lazar was taken prisoner and executed; the Serbs were forced to pay tribute to the Turks and promised to do military service in the Sultan's army.