Hearts of Iron 4 (HOI4) – How to Declare War

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What most players probably want to do in Hearts of Iron 4 is declare war on every one of their neighbors and fulfill their power fantasies. However, this is impossible if you don’t meet some special requirements.

As long as you are playing as a Democratic or Non-aligned country, you will have to keep an eye out on a lot of things to make sure you can actually even think about war (unless someone wants to attack you).

Recommended Read: How to Fix Paratroopers Not Launching in HOI4

Declaring war is relatively easy in HOI4, as you just need to press a button. However, the button will be grayed out until you manage to do all the necessary steps beforehand.

To declare war in HOI4, players will first need to get a War Goal on their enemies. Once they do, if they are a Fascist or Communist country, they can declare war by opening the diplomacy menu with that country and pressing the Declare War button.

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How to Declare War in HOI4

To declare war on any country in HOI4, you will need a War Goal. There are two simple ways to get a War Goal in HOI4:

  • Go Through the Focus Tree
  • Justify War Goal

The first option is what most players will go through, as most interesting countries will get War Goals just by fulfilling special national focuses.

Most countries have a Fascist or Communist national focus path and you can gain a lot of War Goals on neighbors by completing those.

However, the easiest way to actually get a War Goal on a country and declare war is to open the diplomacy menu with them by right-clicking on their country and pressing the “Justify War goal” button.

You will then have to select what War Goal you want to create. The most common one is Conquer, where you select which state you want to annex. It will usually take around 6 to 9 months to justify a War Goal.

Once you have the War Goal, you can open the HOI4 diplomacy menu with that country again and press the “Declare war” button, which shouldn’t be grayed out anymore.

So, the easiest way to declare war on a country in HOI4 would be to follow these simple steps:

  1. Right-click on a country and press the “Justify War goal” button.
  2. Select the Conquest War Goal and then choose the state you want to take. Usually, it doesn’t matter since you will likely conquer everything.
  3. Wait for the War Goal to be justified around 200 days.
  4. Once the War Goal is justified, right-click on the nation again and press the “Declare war” button.

Conditions for War Declarations in HOI4

Fascist and Communist countries can Justify War Goal at any time during the campaign without any limitations. Once they get the War Goal, they can attack whichever country they wish to annex.

Unfortunately, Democracies and Non-aligned countries have to meet some criteria first.

Democratic countries in HOI4 can only justify War Goal and declare war if the World Tension is 100%. Democracies also cannot justify War Goals against countries that haven’t created World Tension.

You can see the World Tension at any time by looking at the top right of the screen at the globe. The number shown under the small globe is the World Tension.

Non-aligned countries can justify War Goals and declare war if the World Tension is at least 50%.

A method that Democratic countries can use to get involved in wars before World Tension hits 100% is to Guarantee the independence of countries that Fascists or Communists might attack.

You can do this once World Tension has reached 25%, and it costs 25 Political Power. Guaranteeing someone’s independence will lower World Tension by 1.7%.

That’s everything you need to know about how to declare war in Hearts of Iron 4!

Have any input or suggestions for this guide? Let us know in the comment section below.

Adrian Oprea

Based in London, United Kingdom, Adrian Oprea is a Guides Writer. As a professional single-player RPG player, Adrian has often been stigmatized. He has decided to pour his frustration into writing guides!

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