Building forts

[Xepheon]

When I am looking at Japanese held islands for example, I see many of them are connected by red lines indicating they can be traveled between without ships, right?
So would I want to build coastal defenses AND land forts? Does crossing between two islands connected by the red lines count as a land attack, or naval?

If the US captures one of the islands, then is able to travel via the red line to the next island, my coastal fort would offer no additional protection, right?

[drewbstar]

Red lines count as naval IIRC so you should build naval forts to hold.

[Xepheon]

Originally posted by drewbstar:

Red lines count as naval IIRC so you should build naval forts to hold.

Naval bases offer protection? I thought they just repaired ships and allowed supplies to be sent and received? Thats what it says in game anyway.

The red dotted lines indicate a strait, and according to the wiki land units can travel between the two areas as long as they have naval superiority.
So im assuming it means that counts as a land attack, so I should build land forts in areas like that as well as coastal.

[TasteDasRainbow]

I'm still not certain whether or not land or coastal forts affect that situation, but I would say regardless that it's rather pointless because of the massive penalties they would take if landing off of the port and instead on a connecting island. Crossing penalties, supply deficiencies that will only worsen, etc. that largely negate the benefits of forts by means of overkill.

In that respect, sticking with coastal forts to simply ensure holding the port against direct naval invasion is all that's really necessary.

[drewbstar]

https://hoi4.paradoxwikis.com/Construction#Province_buildings
Costal forts:

Inflicts an attack penalty of -15% for each fort level on the attacker in naval invasion and 'strait crossing' combat.

Just to recap:
Naval bases (or 'ports', it's easy to get them confused with forts, lol) are what ships use to dock and where they repair. This repair process "consumes" a dockyard which would otherwise be used to build a new ship..

Land forts affect land combat, which does not include strait combat. So if it's a 1-tile-only island (e.g. Midway) then you should build naval forts, as the only way to attack the island is via invasion. If you're in an area where there could be both types of combat (due to geography or borders, like Hong Kong) then build both.