On June 28th 1389, at Kosovo Polje, an army of the Serbian Prince Lazar made a stand against the advancing Ottoman forces of Sultan Murad.On June 28th 1389, at Kosovo Polje, an army of the Serbian Prince Lazar made a stand against the advancing Ottoman forces of Sultan Murad.On June 28th 1389, at Kosovo Polje, an army of the Serbian Prince Lazar made a stand against the advancing Ottoman forces of Sultan Murad.