Shadow,
Let me parse your latest version from my viewpoint as an outsider:
>>>When a journalist gets assigned to a military unit fighting in the second US civil war...
I would view this as the setup. I don't see it as the inciting incident. Because his assignment by itself is not a game changer. It's just another reporting assignment with the usual requirements and expectations -- whatever those are is in the context of the situation.
>>>he will have to fill the unlikely role of diplomat
Entailed in this is his life changing decision at the end of Act 1 that thrusts him into a new role -- one he did not expect, a role he would not assume if he could avoid it. Right?
And why must he play this unfamiliar role? What has triggered this new direction in his story?
>>>to prevent the war reaching his home town.
It seems to me that entailed in this phrase is the inciting incident. Something totally unexpected -- and unwanted -- happens that changes everything for him, that forces him to respond. Only the inciting incident is stated rather generally and comes at the end of the logline when it should come as near as possible to the start of the logline.
So it seems to me that the inciting incident that changes his role, and his life, needs to be stated with more clarity and should be the kick off of the logline instead of the kicker.
Hope this helps.