The Dragon King War or War of the Dragon King (fl. A.R. 281) was a conflict that took place on the planet of Earl 50 years prior to the time depicted in the Mai-Otome anime. The war is noted as the last time that Otomes fought in anger. Many Otomes were involved and Masters even took Garderobe's students for Meisters during the campaigning.
Casualties include Monica Julen from Cardair, who died at the hands of her best friend, an Otome from Florince, as well as Sylvie Mosse, possibly said best friend. Also among the dead were many members of the Ho clan from An Nam, leading to the clan's affiliation with the Schwartz. Masters who lost their lives include Argos XII, the young emperor of Cardair (Monica's Master) and Marc Antoine, the Master of Sylvie.