I had a thought on this for quite sometime now (hopefully no trolls will come and ruin this).
My thought was have every port to have 10 sectors and each sector will have an important building there that will supply resources, like a fish port on one sector will give X food every min or so to your ware house.
A factory that will give you X gold coins every hour and so on.
The next thing is that, how do one take control of a sector, well, I was going and thinking on, that a war will take place, lets say, you hire 1 mill people to protect this sector of the port and you can also hire crew from other ports and dump them on to a sector to protect it.
And when someone attacks the sector, he will need an army ready, which I was thinking of just have you hire them and call them to attack.
The port with the most sector owned by the person of the nation, eg. 7 spain : 2 Midway : 1 Egypt. Spain owns the port.
Population of the target port will also play a roll and so on.
Give me your opinion on this, and please, for the love of god, don't ruin this for me.
Also, to make it so that a problem will not happen, the lower the population of the port, the more expensive it is to hire more "army".