Complex sentence: Unsuccessful at trying to establish peace, the Autobots are forced to fight them until they use Megatron's space bridge to bring through the Decepticon Dreadwing and his Combaticon minions.
Split into simpler sentences: Unsuccessful at trying to establish peace, the Autobots are forced to fight them. They evenutally use Megatron's space bridge to bring through the Decepticon Dreadwing and his Combaticon minions.