In the real timeline, the Ottoman Empire had won the Battle of Kosovo in 1389. In this timeline called Timeline Heliopolis, the Serbs had won the Battle of Kosovo instead of the Ottomans. After the Turkish counterattack aimed at the Serb heavy armor that was charging at the Turkish wing command, the Serbian forces regrouped at the upper hill that overlooked the battlefield, and harassed the incoming Ottoman army. Repeated Serb counter attacks had led to the Ottoman forces retreating from Kosovo all the way into northern Greece.