The Great War was an event in the Shattered Beasts timeline.
The Great War raged on Cybertron (SB) for more than 10 millon years. The winners where the evil Autobots and they imposed an iron fisted rule upon the energy depleted plant. Eventually after many conquests they were forced to undertake The Great Upgrade (SB) which down-sized their bodies and gave them the abiltiy to scan DNA for alternate forms. Unbeknownst to the newly created Maximals a small pocket of Decepticons had survived and mimicked the process coming forth as the Predacons. After this the Predacons used guerilla tatics and began strikeing back at their oppressors, starting the war once again in a new form known as the Beast Wars.