Four million years ago, Cybertron, shaken from its orbit and drifting through space, became threatened when it floated into the path of an asteroid field. Prime led a group of elite Autobot warriors on the Ark, the Autobot starship, on a mission to destroy the asteroids. Although the mission was successful, during the aftermath of this mission, the Ark was attacked by Decepticons hoping to overpower their weakened foes. Intent on keeping the secrets of the Ark from the Decepticons, Prime set the craft on a suicide course, crashing it into the then prehistoric planet Earth.