Great Schism: A Chance for Unity... Denied!
Last year Pope Urban the 6th in Rome was seriously hurt after a fall. Now he has passed away. Due to the split in the Church, there are two Popes: one in Rome and one in Avignon but with Pope Urban dead, the Church has a chance at reunification. Rome is still in the grip of several warlords so it is impossible for any Pope to live there year round. It would make sense to turn to Pope Clement the 7th in Avignon (in the south of present day France) but 14 Roman Cardinals decide to elect another Italian... Pope Boniface the 9th... and keep the Great Schism going. Pope Boniface has no training in Church Law nor administration but he will manage to fortify the Roman defenses so that he can live in Rome at least most of the time. A large part of Europe and England will accept him as Pope with the obvious exception of France and a minority of Italians. In the modern day Pope Boniface is considered the legitimate Pope, but if you had asked Pope Clement the 7th in Avignon, he would have told you sincerely that he is the legitimate Pope.    
Ottoman Turks: The Battle of Kosovo
While the Europeans have been fighting amongst themselves, the Ottoman Turks have been chewing their way through Bulgaria. Sofia has already fallen and the terrain makes the Ottoman's turn toward Moravian Serbia obvious. The key region here is Kosovo so Prince Lazar leads a blocking force to meet the Turks. All the chips are on the table as the Battle of Kosovo turns into a death match. Prince Lazar breaks through the line and kills Sultan Murad the 1st. The sultan's son rallies and kills the Prince in turn. When the smoke clears, almost everyone is dead on both sides, but the Ottoman reserves will be brought forward from the east to blow through what is left of Kosovo and threaten Hungary.    
This Year on Wikipedia
Year 1389, Wikipedia.
- Norwich, John Julius. Absolute Monarchs: A History of the Papacy. New York: Random House. 2011. Chapter 16 "Laetentur Coeli!" (BOOK)
- Pope Boniface IX - Wikipedia, 2014 [last update]
- Pope Urban VI - Wikipedia, 2014 [last update]
- Antipope Clement VII - Wikipedia, 2014 [last update]
- 1389: Saint Tsar Lazar, after the Battle of Kosovo, ExecutedToday.com, 2009-Jun-15.
- Matthias, John and Vuckovic, Vladeta (translators). The Battle of Kosovo (Serbian Epic Poems), kosovo.net, 2009 [last update]
- Emmert, Thomas A. The Battle of Kosovo: Early Reports of Victory and Defeat (from Kosovo: Legacy of a Medieval Battle, 1991). 2014 [last update]
- Battle of Kosovo - Wikipedia, 2014 [last update]
- Archduke Franz Ferdinand of Austria - Wikipedia, 2014 [last update]