Meltdown Riots

The exact circumstances of the Meltdown Riots remain unclear. After the creation of new pint-sized Transformers using the Micromaster process, the Autobots and Decepticons initiated a joint training program for the new recruits. Both factions ran separate training sequences and combat preparation exercises for the new Cybertronians, while simultaneously attempting to impress their own dogma on the Micromasters, so that the Micros would choose to side with either the Autobots or the Decepticons when the time came.

For whatever reason, the Meltdown Riots were that time. Many Micromasters, possibly the majority of them, took up arms and officially chose sides by the time the riots were over. Although it is unclear whether there was global ceasefire between the 'Bots and 'Cons during the training phase, if it DID exist, the ceasefire ended after the Meltdown Riots. Specifically, it's known that Big Daddy and the Hot Rod Patrol first teamed up as a group and joined the Autobots during the Riots. Additionally, Barricade (the Micro formerly known as Runner) gathered his Race Track Patrol during the Riots and convinced them and several other Micros to join up with Shockwave and the Decepticons afterward. Victims of the Revolution

Still, the location, circumstances, and participants of the Meltdown Riots remain unknown.