Excerpts from Books and Wikipedia
The Battle of Kosovo was fought on June 28, 1385 between the armies of the Ottoman Turkish Empire and a coalition of Christian armies from Balkan states under Serbia's Prince Lazar. The kingdom of the Serbs was absorbed by the Ottomans. However, the Serbs preserved their Orthodox Christian culture. "Kosovo became a cornerstone of Serb nationalism, and its anniversary was marked down the centuries." World War I began on June 28 with the assassination of Archduke Franz Ferdinand of Austria. "The Kosovan conflict of the 1990s between Serbs and ethnic Albanians was fueled by the potent issues that Kosovo has come to represent." [Furtado: 1001 Days] "After the battle Turkish empire continued to spread over the Balkans, to finally reach Vienna." [Wikipedia: Timeline of Middle Ages]