The Eternal City
The Crisis of the Third Century was a very real and debilitating event in the history of the Roman Empire. The outside threats and then internal turmoil was devastating and led to decades of pointless wars. Things were so bad at the end many Roman citizens (in Rome itself) appealed to Italian landowners to become in effect serfs in order to get protection and a daily meal that was no longer being provided by Rome.
I used this historical event in the campaign as an instance of having the coterie purely for their own motivations to create the circumstance that set off the crisis of the Third century. They knew the only way they could return safely to Rome would be to actually force the Senux to recall them and answer for something they had done. Engaging in economic warfare was a good way to accomplish this and such the crisis of the Third Century was born. This way they are still actors in a historical campaign instead of mere observers.