This is the most important battle in the history of Serbs.
And very dear victory for the Albanians.
In 1354, Islam invaded Europe. In that year, the armies of the Ottoman Turks moved west and conquered the Aegean port city of Gallipoli. By 1389, much of the Balkans (Bulgaria and Serbia) were vassal states of the Ottoman Empire (see the map at right from The Ottoman Empire: 1326-1699, Stephen Turnbull, Osprey, 2003).
The first counterattack was launched in 1363. Serbs, Bosnians, and Wallachians joined a Hungarian army (under the Hungarian king, Louis the Great) and marched to Edirne (formerly Adrianople). There they planned to attack Sultan Murad and the Turks. Disaster struck when the Christian force was ambushed by Turkish cavalry at the river Maritza. The Christians were routed and fall back in defeat.
Again, in 1371, the Serbs attacked the Turks, and again the Serbs were defeated. This second defeat came on 26 September 1371, at the battle of Cernomen. All the Serbian leaders were killed. This battle, also known as the second battle of the Maritza, is known in the Turkish chronicles as "Sirf sindigi" (the destruction of the Serbs).
The Turks could not be thrown back. In 1385, they captured Sofia and, the next year occupied the Serbian town of Nis.
In 1389, a Serbian leader, Lazar, raised an army to drive the Turks from the Balkans. Lazar raised contingents from Serbia (included forces led by his son-in-law, Vuk Brankovic), Bosnia, Wallachia, Albania, and Hungary.
This Christian force met the Turks at Kosovo Field (Kosovo Polje), the Field of Blackbirds, on St. Vitus's Day, 1389.
The battle and its aftermath:
The Kosovo battle resulted in heavy losses on both sides, but was a devastating loss for the Serbs. Most of the Christian leaders and nobility were killed or driven into exile. Sultan Murad was assassinated behind his lines by a Serbian knight, Milos Obilic, and Lazar was captured and beheaded by the Turks.
Serbian epic songs give two contradictory reasons for the Serbian defeat: the treachery of Vuk Brankovic-- which seems to have no basis in fact--and Lazar's decision before the battle to sacrifice his earthly kingdom for a heavenly kingdom, to lead his men into battle knowing what the tragic outcome was to be.
Complete Turkish domination of Serbia was achieved very slowly by Sultan Murad's successors. A second battle of Kosovo was fought in 1448. The final and conclusive battle was not fought until 1439 for the fortress at Smederevo on the Danube, Nonetheless, it is Kosovo which has lived in the Serbian tradition as the moment of annihilation and enslavement.