As most of us have probably noticed already, war in mostly boils down to there only being two sides that compare the number of damage they can output spread out over any number of battles. There is a lot of managing, coordination and trying to outplay the opposing side etc. going on in the background, one of the core reasons i enjoy this game, but that reality does not change.
Since you can deal the dmg you have available anywhere on the map - something the movement update will hopefully fix - politics inadvertently move into a two block war. Those two blocks try to get more dmg than the other side and once you succeed you gain 100k gold weekly income from taxes, furthering your position of power.
In order to fix that I suggest giving players a dmg debuff depending on how far away from their countrys core regions they are fighting. That would:
Prevent hegemonies, as it becomes increasingly difficoult to defend the largest territories.
Allow for more than 2 blocks, as eg germany or the netherlands fighting in south africa would be wasted dmg, giving them less reason to interfere.
Decrease the trend towards MercEra, as you cannot simply sell your dmg anywhere without consideration of your regional position.
Give the existence of proxies a cost, as they are away from your core regions and thus at a disadvantage when defending you.
If you disagree or have something to add I invite you to to discuss in the comments.
Ps.: https://app.warera.io/user/6813b758efecdf9bab195068 i really like your game, unfortunately there are some problems with the balancing rn. If you can fix that WarEra imo has the potential to become one of the best war sims there are. You have a large community of people really invested in this game, use that, ask for feedback, try to see what people want. Of course that wont always be the best, but at least show us you care about our oppinions