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The Counts of Celje became the most influential noble family in the Slovenian lands from the Late Middle Ages. The Counts are still part and parcel of the collective memory of Slovenians, so much so, elements of their coat of arms are on the Slovenian national flag.^[1]

From the fourteenth century, the family’s political connections reached such a degree that the emperor Louis the Bavarian elevated them to the status of the Counts of Celje. Charles IV of Luxembourg bestowed them the same status. The foundation of their power was the vast property in Styria, Carinthia, and Carniola. By maintaining a close connection with the Luxembourg court, their king Sigismund of Hungary, who later became the German and Bohemian king, as well as the Holy Roman emperor, the Counts of Celje managed to acquire additional territories and titles in the area of today's Croatia. But by the mid fifteenth century (approximately 1457) the political ambition of the family brought about its demise. Seeking higher title in competition with the neighbouring Hungarian king, Ladislaus the Posthumous, led to King Ladislaus’ soldiers silencing Ulrich II of Celje, the last male descendant of the Celje family.

The House of Celje was the last important medieval dynasty which rose to the heights of European aristocracy. When the Counts of Celje became a serious threat to the interests of Habsburgs, particularly Inner Austria, a peace treaty was used against them. Specifically a clause of the treaty stipulated mutual inheritance, which later enabled the Habsburgs to acquire all of the property of Celje within the Holy Roman Empire.

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