Battle of Kosovo, Kosovo also spelled Kossovo, (June 28 [June 15, Old Style], 1389), battle fought at Kosovo Polje (“Field of the Blackbirds”; now in Kosovo) between the armies of the Serbian prince Lazar and the Turkish forces of the Ottoman sultan Murad I (reigned 1360–89). The battle ended in a Turkish victory, the collapse of Serbia, and the complete encirclement of the crumbling Byzantine Empire by Turkish armies.
Murad captured many fortified places near Constantinople (now Istanbul) and used internal troubles in Byzantium and the Slavic states to extend Turkish conquests in the Balkan peninsula. Moving into Serbia, he marched as far as Kosovo, where he met Lazar’s army.
At first, victory appeared to be on the side of the Serbs when the sultan was killed by a Serbian noble, Miloš Obilić, who made his way into the Turkish camp on the pretext of being a deserter and forced his way into the sultan’s tent and stabbed him with a poisoned dagger. The confusion that followed was quickly quelled by Bayezid, Murad’s son, who succeeded in surrounding the Serbs and inflicting a crushing defeat on their army. 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.