Hello Draticus, welcome to the Org

The
"whole faction turned rebel"
thingee ('feature', the devs call it) happens because you are too successful, in my experience. Turn 99 -113 is approximately in the game experience where you (the player), having played a few rounds now, have mastered income accumulation and troop deployment, so the game algorithm decides to throw you a curve: faction-wide rebellion.

It happens to other factions as well, rest assured. The key is watching the morale ratings. Starting around turn 80, if you keep track, even though income seems OK and you've won the battles and provided bread and circuses to the natives, troop morale can start declining - slowly at first, then cascading near the 100th turn/year.

It's not intended to stop you, but to make you 1) watch the morale settings more closely and 2) make good decisions about which side to back, after the rebellion starts. Sometimes, it's best to back the Old King, sometimes it's better to back the rebel step-son. Carefully look at the stats presented, and make your choice. If your choice doesn't work out, pick a replay and go the other way.

Again: welcome to the Org

MTW2 fans hang out here: https://forums.totalwar.org/vb/forum...hp?131-Citadel, where you can also find other tips and tricks.