The Ottoman Empire first reached Bosnia in 1388 where they were defeated by Bosnian forces in the Battle of Bileća and then were forced to retreat. After the fall of Serbia in 1389 Battle of Kosovo, where the Bosnians participated through Vlatko Vuković, the Turks began various offensives against the Kingdom of Bosnia. The Bosnians defended themselves but without much success. The Bosnians resisted strongly in the Bosnian Royal castle of Jajce (the siege of Jajce), where the last Bosnian king Stjepan Tomašević tried to repel the Turks. The Ottoman army conquered Jajce after a few months in 1463 and executed the last King of Bosnia, ending Medieval Bosnia.