Pocus wrote:To be clear you are speaking of land forces moving using the order 'river move' and not using actual transport units, right?
Correct. Certainly so when it is my own troops exhibiting the "immunity to gunboats" feature, and when it is enemy troops immune to my gunboats, both the replay graphics and the end-of-turn intelligence seem to indicate only land forces.
I agree with the other recent comments that the "river move" abstraction is a good thing so long as the river movement in question is both timid and fragile. If the theatre commander hasn't specifically arranged a concentration of naval forces to support a move, he's presumably using merchant shipping chartered as available. Which is quite practical if there is a surplus of shipping, but it gets you riverboats in ones and twos carrying a battallion or battery at a time over the two-week turn, and not commanded by resolute naval officers.
Approximately the same end result as a whole-unit move if there is no opposition, and reasonably abstracted as such in the game. But if there are gunboats or entrenched artillery in the way, the most likely result would seem to be,
A: The first few riverboats turn back rather than try to press through.
B: Particularly if facing gunboats capable of pursuit, there's a good chance that they and their cargo are lost.
C: All the rest of the riverboats in the queue, upon hearing of this, retire to the safety of the nearest port and await more sensible orders.
So, catastrophic destruction of the moving force would be rare. But the whole force patiently waiting mid-river one region away, and always evading the actual naval forces pursuing them, should be similarly rare. Mostly, modest casualties and retreat to a safe port. If for reasons of game mechanics this cannot be implemented, I'd prefer catastrophic destruction of the moving force and a stern warning to the players to Not Do That.
Where actual transports are concerned, everything seems to be working about as I'd expect.