Regent George Mouzalon and his brothers are killed during a coup headed by the aristocratic faction under, paving the way for its leader, Michael VIII Palaiologos, to ultimately usurp the throne of the Empire of Nicaea.
George Mouzalon (Greek: Γεώργιος Μουζάλων, romanized: Geōrgios Mouzalōn; c. 1220 – 25 August 1258) was a high official of the Empire of Nicaea under Theodore II Laskaris (r. 1254–1258).
Of humble origin, he became Theodore's companion in childhood and was raised to high state office upon the latter's assumption of power. This caused great resentment from the aristocracy, which had monopolized high offices and opposed Theodore's policies. Shortly before Theodore's death in 1258, he was appointed regent of Theodore's under-age son John IV Laskaris (r. 1258–1261). He was assassinated only a few days later by soldiers, as the result of a conspiracy led by the nobles under the soon-to-be emperor Michael VIII Palaiologos (r. 1259–1282).