The Beast Wars were waged on prehistoric Earth, eventually leading to the discovery of the buried Ark. The beast Megatron, following the original Megatron's instructions in a desperate gambit, attempted to change history by killing Optimus Prime, who was still lying in The Ark in stasis lock. Megatron hoped that this would result in the Decepticons winning The Great War and the eventual rule of Cybertron by the Predacons, the descendants of the Decepticons. Megatron unleashed a full-power weapon blast at Optimus Prime's face, delivering a near fatal blow. Optimus Primal, however, took Prime's spark into his body to protect it from surgical trauma while his injuries were repaired. The subsequent power increase caused by Prime's spark's connection to the Matrix augmented Primal into the large, transmetal "Optimal Optimus" form with three alternate modes (jet, land vehicle, and transmetal gorilla). Then, with the repairs complete, Prime's spark was restored, and he briefly activated before sinking back into normal stasis.
Optimus later led a convoy in search for a building site for Autobot City, which ran into a Decepticon ambush. Rodimus Prime remembers the Transformers greatest battle on Earth. He sent off several Autobots to get help, knowing this was the only chance of victory. Transformers Combat Data Those several Autobots were seen again, but Prime... wasn't.
The Autobots United 5 Pack includes another redeco of Voyager Class Evasion Mode Optimus Prime. This release features the faceplated headsculpt and, unlike the rest of the set, which strives for screen-accuracy, features a heavily Generation 1-inspired deco. Deco changes include replacing most of the blue & grey plastic into red, with blue paint applied on it, and his dark grey plastic is now a lighter shade. His Ion Cannon is now painted black to resemble his Generation 1 toy's blaster, color-wise.
If Optimus ordered his troops to come to the humans’ aid, they found themselves taking part in a struggle in futility, as the entire town was near-weightless, meaning they couldn’t put the humans anywhere where they wouldn’t float away once more. Then, the Autobots heard Decepticons approaching. Helpless in their current position, the Autobots were quickly eradicated by the Decepticons.