If you capture an enemy city or port, the enemy can amass forces in that city and press the Revolt button. This happens instantly, and you immediately begin the battle.
If you need to destroy the enemy's accumulated forces yourself, you must remove the army/navy from the city/port and then attack again.
Under the standard scenario, this takes 30 minutes without bombers/carriers, or 1 hour with them.
During this time, the enemy can successfully load their troops and sail off to an unknown destination.
This mechanic contradicts reality and makes destroying the enemy online impossible.
Imagine this in real life: an army besieges a city, wants to kill the remaining troops. It withdraws everyone from the city, then attacks again, instead of storming the city.
I propose:
Introduce an "Assault City" button for the player who has occupied the city or blockaded the port.
After the attacking player presses the button, the battle immediately begins, just like when the defending player presses the Revolt button. A limitation should be introduced: for example, a player can only attack Assault once per day.
This will equalize the playing field between attackers and defenders. It will make online battles more interesting.
It will add variety to the gameplay.