What is the purpose of interdicting ports?

[AlbertN]

I noticed that even if a Port goes down to 0, the relevant town associated retains its supply capability.
It happens in China, with their starting coastal town that gets isolated - the port goes down to 0 but the Settlement still supplies to 5.
It happens in New Guinea, where Port Moresby keeps supplying at 5 level. And so forth.

So what's the point of having ships sitting out of a port, and reducing the port down to 0, if the town still supplies the troops fully, and the town does not degrade over time as well?

[Feinder]

I'd say that interdicting ports is more important in PBEM than in vs. AI.

At the very least, if you interdict a port that has a convoy out of it (like New Zealand), it will completely shut down the convoy. That's kind of big deal when you consider that if you paste the port at Sarawak, Japan loses 23mpps per turn, until it's repaired.

If you want to invade an island, you'll need to bomb the town/supply, and also bomb/blockade the port. A unit on a small island that remains in supply because the port is open, is probably going to win any protracted attack by an invasion force.

Also, esp in PBEM, if you're going to invade somewhere, you'll probably need to destroy or in the least blockade the port. If you don't destroy or blockade the port, your opponent can simply land reinforcements at the base, which will throw your invasion plans into disarray.

[Tanaka]

I noticed that even if a Port goes down to 0, the relevant town associated retains its supply capability.
It happens in China, with their starting coastal town that gets isolated - the port goes down to 0 but the Settlement still supplies to 5.
It happens in New Guinea, where Port Moresby keeps supplying at 5 level. And so forth.

So what's the point of having ships sitting out of a port, and reducing the port down to 0, if the town still supplies the troops fully, and the town does not degrade over time as well?

Follow this to see good examples:

https://www.youtube.com/watch?v=b68KCfv ... BF&index=1