The Irish

The Irish are a group of survivors, taken in from inside (and outside) the prisons by the cartel. They are a couple hundred people within the group.
Their objective is to find as many of their irish brothers and claim a piece of land they are going to call New Ireland. 
They are introduced after the fall of the White power, when they claim that territory and the community is under their juristiction. They are generally calmer than the rest of the empire, and sometimes kind. Over time, their leader and William come close, and the leader comes to trust William and reveals his plans. He says he joined the empire only to save his fellow IRA people imprisoned throughout the US. Also, he fears of what the empire has become, and makes great efforts to prove to William that he is not like the nazis or the empire.  
A while later, the irish collaborate with the community and turn against the empire.  
The Irish trick the community during the war and attack a stadium where people fought for the amusement of others. The Irish thought other irish people were in there, that's why they tricked the community, and burned the stadium down, burning lots of Empire people within it. William was frustrated with this, but he did not move against them. 
There is a snitch within the irish, who informs the empire of the coming betrayal. The empire strikes, and destroys the New Ireland, killing many families and people. Maybe the empire will do to the Irish something bad that happened to them during their story (gonna have to look that up)