One thing I notice since for a long time is that it appears to me that you are only really at war with one nation.
Aka that while you are technically maybe in war with many nation the game only generates missions against one.
Alliance warfare seems to be the biggest weakness of the game right now, in terms of campaign.
Wars escalate fast into constant war worlds, because the way one war always effects everyone relation ships. then we don't really have proper alliances because we don't end wars together but every nation (and AI nation rarely seem to end wars with each other) makes separate peace (something that was ironout during the 19th century, since no one was keen to accept that anymore).