(Planet of the) Apes travel back in time from the far, far, faaaaar future to conquer pre-Apocalypse earth with their giant lizard cyaborg.
We are saved by the real giant lizard and — ironically — Caesar, from whom the Ape founder took his name.
Also explains the Apes’ desire to get control of the King.
This totally factual historical event is chronicled in the always awesome Godzilla vs. Mechagodzilla.