Except...Oligarch was formed from an unsanctioned secession from Sirion. That's pretty much as aggressive as they can get.
It depends very much how you view it. In the original plan 2 more dukes were supposed to join as several in the council thought it was a good idea, of course that backfired :p
But even then Oligarch offered an alliance to Sirion, which puts the seccession in a bit of a different daylight I'd say. But to every their own of course
