Having destroyed Optimus Prime, Megatron believes that his victory over the Maximals has been accomplished, until Prime's life is saved by a very unlikely source. The Maximals rush to save their ancestor, which means putting his spark into the body of Optimus Primal, thus upgrading him to 'Optimal Optimus.' In this state of vulnerability, Megatron orders the destruction of the Maximal base, thus forcing the Maximals to move into the Ark to forever protect their ancestors.