Mortal Combat

In this episode, {Galvatron} and {Optimus Prime} have a battle over leadership. Hotshot and the united army of AutoBots and Decepticons attack Unicron once more. During the battle, Optimus was slashed by Galvatron's dagger. Galvatron was urging him to get up after he fell. Optimus struggles to get up and a blast from one of the ships sent the two rivals out of Unicron. In the end, Optimus thinks he was failed as a leader and exiled himself to parts unknown.

From Teletraan I: The Transformers Wiki, a Wikia wiki.