I'm still trying to work out the things that stop an enemy armies movement. Diplomats seem to do this, if left in a pass they generally seem to prohibit other armies... but not entirely sure if this works 100% for Allied armies too?
Similarly with Forts. I've never had one attacked, and not had one bypassed by allies yet. But do they stop everything, including foreign Diplomats? Are they attackable?
I want to take over a lot more of the world before addressing the Problem of the Bruti & Scipii, and having curtailed their expansion possibilities, would like to create some impassable areas for them.
Can you build forts close enough together to create a 'Wooden' Curtain'? Not tried that yet.
Would really like to buy some nice sewers too instead of bribing all their armies out the way all the time....