The Battle of Nicopolis took place on 25 September 1396 and resulted in the rout of an allied Crusader army of Hungarian, Croatian, Bulgarian, Wallachian, Polish, French, Burgundian, German, English, Knights Hospitaller, Iberian, Italian, Bohemian, Serbian and Byzantine troops at the hands of an Ottoman force, raising the siege of the Danubian fortress of Nicopolis and leading to the end of the Second Bulgarian Empire. It is often referred to as the Crusade of Nicopolis as it was one of the last large-scale Crusades of the Middle Ages, together with the Crusade of Varna in 1443–1444. By their victory at Nicopolis, the Turks discouraged the formation of future European coalitions against them. They maintained their pressure on Constantinople, tightened their control over the Balkans, and became a greater threat to Central Europe.

The Kingdom of Hungary was a monarchy in Central Europe that existed for nearly a millennium, from the Middle Ages into the 20th century. The Principality of Hungary emerged as a Christian kingdom upon the coronation of the first king Stephen I at Esztergom around the year 1000; his family led the monarchy for 300 years. By the 12th century, the kingdom became a European power.