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In page Coronation of the Hungarian monarch:

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After the death of King Albert in 1439, his widow, Elizabeth of Luxembourg, ordered to one of her handmaidens to steal the Holy Crown that was kept in the castle of Visegrád, and with it she could crown her newborn son as King Ladislaus V. The relevance of the strict conditions from the coronation were fulfilled without questioning, and for example King Matthias Corvinus ascended to the throne in 1458, but he could be crowned with the Holy crown only in 1464 after he recovered it from the hands of Frederick III, Holy Roman Emperor. Only after this, Matthias started with internal and institutional reforms in the Kingdom, having been considered as the legitimate ruler of Hungary.