Battle of Kosovo Polje, (October 16–17, 1448).

Four years earlier the Hungarians were badly defeated by the Ottomans at Varna. Their leader, János Hunyadi, gathered a new army 25,000 strong, including knights from Transylvania, hussar cavalry, and Landsknechte infantry.

Hunyadi inflicted major casualties on a much larger Ottoman army led by Sultan Murad II. The key to initial Hungarian success was deployment of arquebusier infantry, which held the field on the first day. However, the next morning Hungarian lightly armed and armored hussars were overmatched by Ottoman sipahis (heavy mailed cavalry) on the flanks of Hunyadi’s infantry. That allowed the sheer weight of massed Ottoman forces, infantry and cavalry, to overwhelm the Hungarian and German infantry at the center of the line, which bent backward under heavy assault, then broke.

When Hunyadi saw the defeat of his flanks, he attacked with his main force, composed of knights and light infantry. The janissary corps were not successful and the cavalry made progress through the Turkish center, but were stopped at the Turkish camp. When the main attack was halted, the Turkish infantry regrouped and successfully drove the Hungarian knights back. The light cavalry, who were now without the knights' support were also overcome. Hungarian forces retreated to their camp. During the retreat, the janissaries killed most of the Hungarian nobles and Hunyadi fled. However, Serbs later captured him. During the night, Turkish infantry fired missiles at the Hungarians who replied with cannons. On the next day, a final assault totally annihilated the remaining Hungarian army.

Casualties were enormous: half the Hungarian army never rose from the field while over a third of Ottoman troops were dead or wounded by the end of the second day. But the Ottomans could more readily absorb such loss.

This battle demonstrated that the Janissary corps, even if their lines were broken through, would not run away from the field if defending the Sultan himself. Otherwise, one major defeat of the Turkish army could have caused only a short turmoil - it would have needed several defeats in a series to break the power of the Ottomans.

The Christian Balkan states were unable to resist the Ottomans after this defeat, eventually falling under control of the Ottoman Empire. Hunyadi successfully defended the Kingdom of Hungary against the Ottoman campaigns. Skanderbeg also successfully continued his resistance in Albania until his death in 1468, 10 years later the country fell to full Ottoman control.