War Within is a Transformers canon theme. Taking place on the planet Cybertron, two factions of transforming robots — Autobots and Decepticons — duke it out for supremacy of their home planet. A little bit about the activities that occurred during that time:
Eons ago on Cybertron, the Great War is in its early stages, with the vicious Megatron cutting a swath through the ranks of the Autobots. When the previous Prime is killed, the High Council chooses a common data entry bot to step up and become the new leader: Optimus Prime. But not everyone is happy with the new choice, as his initial command decision is to surrender Cybertron to the Decepticons. Meanwhile, Megatron works to activate planetary scale engines which could remake the face of Cybertron. He needs one thing to power them… and Optimus Prime has it.
The Dark Ages sees the Autobots and Decepticons split into multiple factions following the loss of their leaders, Optimus Prime and Megatron. The destructive combiner teams are neutral by treaty agreement; and the conflict has simmered down to a low boil. Into this conflicted milieu comes the evil Fallen, who employs the Chaos Trinity to help him bring back an old friend, using the sparks of four genetically unique Transformers.
The Age of Wrath finds the various factions on the brink of signing a peace accord, with the Autobots coming out on top after the Border Wars. The ceremonies are rudely interrupted by the arrival of Megatron, however; soon the Decepticon leader has conquered the entire planet with an army of drones, with most of the Autobots enslaved. A band of Autobot freedom fighters captures one of the drones to study, while searching for the lost Optimus Prime.