How do you defend against a Naval Invasion?

[Warhammer]

Back in the HOI 2 days, it was fairly simple to put a infantry/garrison division on a province that can be invaded (sand graphic). In HOI 3, I made cheap 2 brigades of militia and/or garrison divisions and just sprinkled them along the coastline, more to serve as a early warning system and a speed bump while I rush defences there.

From what I see in HOI 4, you can carry out a naval invasion anywhere and there isn't any warning if its about to commence (in a DD they did talk about a invasion pop up but I've not seen it). How would you defence your coastal provinces? Make 'cheapo' divisions of 2 infantry battalions each and just line your coast? Perhaps stagger them so every other coastal province has a division?

The scenarios I'm thinking off are protecting Nat Chi's coastline from Japan and a German occupied France from a D-day event. Also I've heard that all you need is Naval Superiority for the invasion to go ahead or is Air superiority also needed? Thanks for any information.

P.S. Has there been any WWW where an AI is seen reacting to a invasion or were the provinces just bare and undefended?

 

[Sotahullu]

Well my idea is simple.

1. Keep watch on enemy forces and try to predict possible invasions.
2. Rather then focus on all of the coastlines it's better to hold on major ports and cities. Invading armies need supplies and they need ports for that.
3. Mobile reserves absolutely. These may just have second grade equipment (older tanks and captured equipment) but it's better then nothing.
4. Aerial supremacy. Successful invasions need air superiority but contesting that can give you a edge.

 

[Sorime]

Step 1 : Have a navy
Step 2 : Use a little ressources to put real units on each port, fortifiy them a bit and have some reaction forces
Step 3 : ???
Step 4 : Profit


Without access to a port quickly they won't have much units because supply will kill them and without much units they won't get access to a port. Naval invasions are easy to start, not easy to finish sucesssfully.

 

[Scutatus]

Air power would be an asset I would think. Naval bombers on patrol would give warning - and hopefully do early damage. Similarly, submarines on patrol would give similar early warning one hopes. You would at least know it is coming. As to protecting the beaches- I don't know, without knowing where they are actually landing, guarding against invasion on the coast itself will be tricky. However, any beachhead established by an invasion will be initially quite weak, so perhaps a response force slightly inland that can envelop and overrun the beachhead quickly might be a better approach than trying to guard every inch of coast? In addition, for any invasion to succeed a port must be secured very quickly to establish supply lines. So perhaps if you make sure ports are very heavily defended and untakeable, you might be lucky enough to just sit back and watch as the invaders wither away from lack of supply?

 

[kviiri]

You can also build coastal forts. I think these are best used on ports and cities, to make it harder for the enemy to pierce a location they can immediately begin to supply.

 

[Kevonfor]

Yeah, as previously said, you can prevent naval invasion by having naval supremacy (You can't launch operation Neptune without naval superiority) + Invasion troops won't have a lot of supplies and they will need to take a port for this. if you successfully defend your ports, ennemy troops will run out of supplies and you'll crush them easily !

Or you can defend the province where the invasion take place herself. Enemy troops will have a huge disadvantage (if they're not marines) with amphibious assault. You can also build coastal fortifications to have even more bonuses !

 

[Warhammer]

Hmm ok, lots of good ideas though I'm thinking from the perspective of a country that can't build a navy or have a weak navy, so Naval supremacy is harder to achieve. I guess simply dotting the coast with 'speed-bump' divisions would be a waste and its better to just properly garrison cities and ports?

 

[Kevonfor]

Depends on your strategy I guess. You can let the enemy troops starve until they're easy to crush under your boots while you're sitting comfortably in your fortified ports, or you can maintain a sort of "front line" on the coast with a lot of divisions & coastal forts. I don't know if both strategies will be viable but it may be worth investigating !

 

[CyberianK]

A decent number of cheap forces all around your territory on garrison duty.
Plus a small but potent tank or motorized force in reserve.

Ports and important cities are automatically defended by garrison orders. Then when the enemy landed drive them out with your reserve. Hopefully you also have air superiority that should help a lot.

 

[Jamey]

Hmm ok, lots of good ideas though I'm thinking from the perspective of a country that can't build a navy or have a weak navy, so Naval supremacy is harder to achieve. I guess simply dotting the coast with 'speed-bump' divisions would be a waste and its better to just properly garrison cities and ports?

I think that the usefulness of speed bump units will depend on details of the game and your resources. If the speed bump is big enough that you can get higher quality units to the beaches before a landing is complete, you could wind up fighting with your enemy having the naval invasion penalty.

 

[panzerzombie]

I prefer the - I call it so - Matchstick tactics. Ports are heavily guarded and fortified ( beaches are not ) and like the stick from the matchstickhead a short line of fortifications leading inland are constructed and garrisoned to keep up a supply line to the ports and to prevent an envelope.

Lots of small but artilleryheavy units as defenders.

 

[Sir Garnet]

Is it certain there is no means for a trickle of supply along the coast outside of those ports important or strategic enough to appear on the map? It is a rather severe simplification in HOI3 to force limits on gameplay, but HOI4 has different mechanics.

 

[Red Roo]

I love the attention city and port tiles are getting, it makes it much more realistic as you have to actually aim for them, giving them strategic value. That being said, garrison ports/cities, have a mobile reserve and have a few extra troops in the region in the event that a successful landing occurs.

 

[kviiri]

Is it certain there is no means for a trickle of supply along the coast outside of those ports important or strategic enough to appear on the map? It is a rather severe simplification in HOI3 to force limits on gameplay, but HOI4 has different mechanics.

I'm not sure if that's very realistic. The thing is, either you can land a ship to provide supplies or you can't - it's not binary but quite close. Sure old Gaston might have a small pier near his manor in Bretagne where you can moor a rowboat, but a rowboat can't carry supplies for ten men to last ten days, let alone an entire division, nor cross an area as large as the English channel.

 

[panzerzombie]

I'm not sure if that's very realistic. The thing is, either you can land a ship to provide supplies or you can't - it's not binary but quite close. Sure old Gaston might have a small pier near his manor in Bretagne where you can moor a rowboat, but a rowboat can't carry supplies for ten men to last ten days, let alone an entire division, nor cross an area as large as the English channel.

Not entirely true, the landing boats that ferry the troops could - in an emergency - ferry supplies as well.....but ofc much less so than a directly moored merchant at a proper port facility with cranes and stuff.

Almost every landing in the Pacific - not counting tiny islands - had to make do with inadequate facilities ( e.g. Guadalcanal, NewGuinea )

 

[Sir Garnet]

Steering clear of discussion of logistics (which are banished to their own sticky thread):

My question is focused on the operational considerations of invasion and resisting invasion, and in this case whether a port (meaning one shown on the map, or in some cases pre-built or built on site (e.g., mulberries)) must be acquired within a specific (or variable) time window after landing as an absolute prerequisite to (a) maintaining a lodgment, or (b) expanding from the lodgment.

Consider the invasions of Turkey at the Dardanelles in 1915 (Gallipoli), where Commonwealth forces maintained a beachhead engaged with the Ottoman enemy for an extended period of time without benefit of a port until it was decided to give up the invasion. They had a large fleet with naval supremacy, and air attack was not an issue.

In HOI4, would they just waste away in Org, fleet or no fleet? From another thread, it sounds like they could not be withdrawn or retreat to transports if in combat in HOI4, meaning that the enemy pinning them in combat with air or land attacks would in the long run ensure their destruction unless relieved by fresh forces that force the enemy to cease attacks. So this is the "port-or-die" situation.

One alternative design would be that a certain size fleet be enough to maintain over time a lodgment of a force of a certain size only, or for defensive purposes only after its offensive capabilities are exhausted, but failure to take a port quickly enough would mean the landed force is going nowhere.

From the defensive perspective in WW2, keeping the enemy on the beaches and trying to drive them into the sea was a prime goal of the defensive and counter-attacking forces, since a beachhead of any significant size might be reinforced and break out. In the port-or-die situation, once the clock ticks down the invaders can do nothing and the defenders can stand easy and harass the landing force to keep it n combat until it weakens enough for easy destruction. Unless fresh troops are landed, of course, and can expand the lodgment enough to make it possible for worn troops to be withdrawn.

The key operational point is that an invader force fails if it does not connect to a friendly-controlled working port within the time window, and defending forces can be used accordingly. This greatly simplifies coastal defense strategy, which may be the objective.

 

[jcd000]

Well, if i can land a big enough stack on a beach, then use this stack quickly enough (remember to include armor) to capture the adjacent port before going out of supply (within 1-2 days), job's going to be easy.

I mean, if the USA goes for a real invasion, 3 German divisions on each port won't be enough to stop a real invading 12 unit-stack with armor from doing that, and the reaction forces won't be able to react, unless you got them close enough = you got many of them around.

Unless ports are fortified by land with lvl5+ forts - which is costly as well...

There seems to be an advantage for the invader here?

 

[Sir Garnet]

There seems to be an advantage for the invader here?

Yes, along with any coastline being OK for amphibious landings of any size, rather than a more limited set of good and adequate amphibious invasion sites that would let the defender prepare better, in which case maybe the port-or-die imperative might not be needed as a counterweight.

 

[KalZakath]

Another thing from Da9l's WWW as Japan is that if you land and can grab enough land to gain 51% of a state/area, you're able to use the supply from the state. That probably isn't going to be enough to launch a major offensive from there or anything, but it could make it enough for the invader to be really difficult to be pushed out. With some of the smaller states/areas this might be a quick thing that will let you be more leisurely about the taking of the ports to get the full supply in.

 

[geogus]

Is it true that EVERY coastal pronvice can be invaded by sea.

The beaches are removed?
I domt like it