I suggest removing the peaceful and non-peaceful towns system and making all towns in nations siegable. Towns would be divided into two categories - fort and not a fort. When non-fort towns are sieged pvp is enabled, but destroying blocks by the opponent wouldn't be possible and the town itself will not be able to fire cannons and artillery from within its claims, while destruction of blocks will be possible when forts are sieged. Forts would still maintain their importance as the foundation of a nation and the necessary element of its existence (a nation can't exist when it doesn't have at least 1 fort town). When a fort is occupied by an invading force after winning an offensive siege, all surrounding towns of the defeated nation are not occupied. If the attacker wishes to occupy the nation completely, they'll have to siege every individual town. A nation whose forts have all been occupied will not be able to expand (recruit new towns), participate in other sieges to help allies, withdraw money from the nation bank.

Such a change will completely erase the need for siege bases, battles and conflicts between nations will spread across vast areas of territory instead of being local in only 1 fort, will introduce urban warfare to nations and will overall just make wars more realistic.