Alright. Someone earlier in this thread mentioned the red orchestra 2 style multiplayer campaign. Im going to expand on that considering I also thought this was an amazing idea.
If you don't know. In red orchestra there is a multiplayer campaign map for both the WW2 German/Soviet front and Pacific Theater with Japs/Americans. As seen in these screenshots:
How it works is that one team (depending on whoever won the battle) will choose to attack a territory( they can vote to defend if they wish). After the attacking team chooses the territory, then multiple maps will show up. These maps change depending on what territory you want to attack. The teams will vote on what map they want and then they will load in the map and fight.
Based on how many loses each team takes(in terms of tickets ie deaths) they will lose combat power. To be completely honest i don't know how the combat power works in the campaign so heres from the wiki:
So if the attacking team wins, they get the territory that they voted to take. If the attacking team loses then the DEFENDING team then gets to counter attack, they vote for what territory then once they pick the territory they then pick the map.
I drew up something quick in photoshop that could show how this looks like during the Napoleonic Wars. Im not extremely familiar with the specifics of the multiple coalition wars against France but I tried to base this map off the "War of the Seventh Coalition". Of-course Waterloo and many other campaigns took place during this time. Im not 100% sure this map is correct in terms of borders but it is purely as an example:
Obviously, UK(RED) will lose if they lose all their territories, and France(BLUE) will lose if they lose all their territories. UK would most likely attack, for example Wallonie, and if they lose then France gets to counter attack lets say an area in Holland.
Now the interesting thing about this is that naval invasions and naval battles could take place on this "multiplayer campaign". For example if the Coalition forces get pushed out in Holland then France has to defeat the British navy in the channel just to invade the Isles. Or the British navy could launch a new Invasion into Normandy or other coastal provinces(after beating the french navy of course).
If you would like to look at how its done in red orchestra 2 check here: http://wiki.tripwireinteractive.com/index.php?title=RO2_Multiplayer_Campaign
PS this will be purely multiplayer PVP with no AI. Each map would have to be an objective based one. Possibly add sieges to some provinces to add flavor.