Complex sentence: Ultimately they were able not only to influence the affairs of state but also to choose who became the next emperor, they used their wealth to build their own armies and had a loyal band of men who did their bidding.
Split into simpler sentences: Ultimately they were able not only to influence the affairs of state but also to choose who became the next emperor. They used their wealth to build their own armies and had a loyal band of men who did their bidding.