Most Allied countries in Hearts of Iron 4 are really far from Europe. This is why most of them will have to use naval invasions to actually set foot on mainland Europe and defeat the unstoppable Axis powers.
However, to naval invade in HOI4, you have to do more than just press a button to send your troops, as you would on a frontline.
Recommended Read: How to Increase Manpower in HOI4
Naval invasions are relatively complex and will require you to meet certain criteria for them to work.
To naval invade in HOI4, you have to select an army and create a Naval Invasion Order. Depending on the number of divisions, it can take at least 7 days for the troops to prepare. The troops can only start the invasion if you have Naval Supremacy in all the sea regions they have to go through.
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How Naval Invasions Work in HOI4
Naval Invasions in HOI4 are special operations where you send troops behind enemy lines by putting them on your transport ships and landing on their coastal territories.
The number of divisions you can use for a naval invasions at the same time is limited by the Naval Invasion Capacity stat, which you can see in the Officer Corps menu.
At the start of the game, most countries have 0 Naval Invasion Capacity, meaning they can’t launch Naval Invasions.
You can increase the capacity by researching Transports technology in the Naval Support category.
An invasion needs planning before it can be executed. If you planned a naval invasion with one single division, it would take 7 days for that plan to prepare. If you have 10 divisions, then it will take 70 days.
The more divisions you have in a Naval Invasion, the longer the preparation time. If you plan on attacking a country, make sure to start your Naval Invasion plans before declaring war.
There is no way to “cheat” the preparation time, as you cannot prepare 10 different invasions with one division each in 7 days. That would still take 70 days since the preparation time is shared between invasion plans.
You will also need a lot of Convoys to make the troops advance from your coast to your enemy’s. The number needed is based on the weight of the divisions that you want to use.
Naval invading forces receive a huge 70% debuff to Attack and Breakthrough, making naval conquest very hard.
You should aim to conquer provinces that don’t have a port and then quickly make your way to capture one once the troops reach land.
How to Naval Invade in HOI4
Here is how to successfully naval invade in HOI4:
- Select one of your armies and press the Naval Invasion Order button (anchor icon with an arrow).
- Left-click on the province where you want your troops to leave from.
- Right-click on the enemy province where you want your troops to land.
- Activate the execution of the plan.
In theory, if you manage to meet all the necessary requirements, your troops will start leaving once they finish their preparation, and you can watch them as they make their way toward enemy lands.
Here are the two most important requirements you need to meet for a Naval Invasion to actually start in HOI4:
- 50% Naval Supremacy in all sea regions where the troops will have to navigate.
- Enough Convoys to carry the troops.
- Enough Naval Invasion Capacity.
Naval Supremacy is hard to attain in a lot of regions at the same time, as you would have to use more fleets for the various sea provinces.
Most of the naval missions help with getting Naval Supremacy. However, the best ones are:
- Strike Force
- Naval Invasion Support
Usually, you should select the Naval Invasion Support mission, as the fleets will also protect the naval invasion divisions from attacks.
The worst thing that could happen to you while launching a Naval Invasion is to get your troops destroyed by enemy fleets.
Large ships have better scores for getting Naval Supremacy, so make sure to use Battleships to control the waters properly for your invasion.
You can tell you don’t have enough Convoys for your Naval Invasion in HOI4 if the troops assigned to the plan get the red exclamation mark (!) next to them.
Hovering over the arrow showing the invasion plan will tell you if you need more Convoys for the troops to leave.
The number of Convoys you need for a Naval Invasion is based on the weight of the divisions. Usually, normal divisions are relatively light, as support companies, infantry, and artillery aren’t that heavy.
The heavier types of battalions in HOI4 usually also have the word “Heavy” in their title. Modern Tanks are also three times heavier than normal battalions.
Naval Invasion Capacity
One of the most common reasons why Naval Invasions don’t work is the lack of Naval Invasion Capacity.
You can always check your current Naval Invasion Capacity by opening the Officer Corps menu (button with officer cap under Convoys) and going down to Navy Command.
That number tells you how many divisions can participate in Naval Invasion plans at the same time. You can quickly research the Transport Ship technology to increase the capacity to 10.
The next Naval Invasion Capacity upgrade comes around 1940, so you will have to make do with these 10 divisions.
If you assign more divisions than the Naval Invasion Capacity, then you will get an error similar to the one with Convoys, with a red exclamation mark. You can see the error appear on the arrow showing the Naval Invasion plan.
That’s everything you need to know about how to naval invade in Hearts of Iron 4!
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