The following groups have made attempts at taking control of the empire by force or have commited armed attacks inside the ICS.
The People's Republic of Continentis Septentrionalis (PRCS) is a communist rebel group with roots dating back to 1950. At one point it managed to take control of most of the empire but lost it due to internal and external issues.
They currently carry out attacks on military bases and small towns.
The PRCS is Kill On Sight, collaborating with them can lead to death or worse.
The New Way is a rebel group that is attempting to make the ICS democratic, they did not start violent but over the years they have started to take more radical actions to send their message.
Their leader is choosen through votes with them needing to have majority to become the leader.
Currently TNW is Arrest On Sight, collaborating with will lead to harsh punishment but not the death penalty.