In 1986, the Ultrasaurus was released, and billed in-story as the machine that would defeat the Empire. It nearly succeeded, but Zenebas and his forces fled to the Dark Continent Nyx, soon returning with new-model Zoids like the Death Saurer. The Republic was driven back and forced to hold the Empire off with guerrilla warfare in the mountains, paving the way for the brief 1/24 scale line (notable for featuring the Battle Rover as the winner of a fan design contest). The Republic's counterattack came in the form of the Mad Thunder, and as Zenebas again turned to the Dark Continent for help, he was betrayed by Guylos, whose new "Dark Army" Zoids attacked and absorbed the Empire Army.