In April of Imperial Calendar 489 (Space Calendar 798), the Galactic Imperial Fleet led by Admiral Kemp suddenly appeared in the Iserlohn Corridor. An extremely fierce assault on Iserlohn Fortress began. At that time, Yang, the commander of the Iserlohn Fortress garrison fleet, was absent due to attending an inquiry. As a defensive battle centered around Caselnes, who served as acting commander, unfolded, news of the Imperial Army's surprise attack also reached the capital Heinessen, where Yang had been summoned...