Diplomacy: penalty for attacking an invading faction

[Septentrionalis]

I found myself recently in a situation in which a previously peaceful faction that I had not provoked directly started amassing troops within lands that I controlled. Okay, I had conquered the area from a mutual enemy, which could also in real life be considered a hostile action. I was naive and let them do that, as I was expecting them to just move their units through my area to attack the mutual enemy. I was wrong. They attacked us.

Once bitten, twice shy. Now I face the same situation with another faction. I need to make a quick decision and end the threat before they have time to build up a force to be reckoned with. My spies tell me that there are plenty on their way towards my settlements, and the expeditionary force is already right outside my border settlement, deep within my area. As I am reinforcing my position as much as I can, they refuse to siege for the time being but await reinforcements of their own.

Is it so that there will be a diplomacy penalty to me even if I attack a neutral faction within my own area? In real life, amassing troops within someone else's lands would be a declaration of war in itself, but the game seems to merit starting a war to whoever initiates violence. Do I suffer diplomacy penalties if I attack, or should I somehow provoke them to attack first at my own disadvantage?

[nvm]

That's just how Total War works. AI is not exactly subtle with this. The golden rule for most mods is - if you are neighbouring a faction, expect the possibility of going to war with them sooner or later. Of course there are exceptions, such as some mods making allies or factions with very high relations avoid doing that, or every faction ever ganging up on you immediately like in original M2TW 1.0 even if you play as England, but this seems to be standard for EB.

As far as I know, there's no diplomacy penalty in EB2 for declaring war. Not right now, at least. Diplomacy is also somehwat incomplete.

[Septentrionalis]

As far as I know, there's no diplomacy penalty in EB2 for declaring war. Not right now, at least. Diplomacy is also somehwat incomplete.

Thanks a lot for help. I mainly try to stay out of conflicts, build, and conquer only those that I have had to fight in self-defence.

Just to be sure we are talking about the same thing. No penalty means that the other factions won't feel any worse about us even if we attack another faction? Out of curiosity, if we were to attack an ally, would that also not affect?