War Machine: Division Theory in Hearts of Iron IV

By Joe Robinson 11 Aug 2016 0

This article was written in collaboration with the Loresworn Order, who provided a lot of the theory-crafting behind today's piece. Also thanks to this Reddit thread, which has a lot of tips beyond what we talk about today. Additional thanks to reddit user 'billguncrash' for writing int with some additional tips and pointers.

If you're a wargamer who's into his/her videogames, you'll most likely have seen (if not played) Hearts of Iron IV. The fourth iteration of their 'grand strategy wargame', Hearts of Iron manages to keep the classic Paradox grand-strategy scale, but focus it into a wargame context by having players navigate the political, and then military landscape of the world between 1936 – 1948.


An integral part of the game, as you can imagine, involves fighting in the wars that erupt during this era. While history is directed a bit more than it is in other Paradox games, there's actually more flexibility here than previous iterations. So while you're always fighting, in a very general sense, the second 'War of the World' the nature and course of that war can be radically different every time.

Land, Sea and Air... And then more land

While HoI IV has dedicated mechanics and systems for fighting in the air as well as at sea, at its heart (… of iron?) this is a game about land wars. To fight the land wars, you need to create divisions using the wonderfully flexible, and slightly impenetrable Division Designer. What does it all mean? What do all those stats do? What defines the effectiveness of one Division vs. another? That's where we come in.

First off, you'll want to watch this video. TJ's done a great job at breaking down what all the stats mean, even if he is dropping F-bombs like its the Battle of Britain. With a basic understand of what everything does, you're ready to start looking at how to craft divisions.

There are a few basic things to remember:

  • General consensus is that Combat Width of a division should be kept at or below 20 (see section below).
  • Research & Doctrines will affect some of the basic principles laid out here, as will more advanced models of things. Always check the tool-tips.
  • Always keep in mind the production capacity of your nation. If you're a smaller, poorer country you will need to scale down considerably.
  • Changing division templates costs XP, which can be hard to get in the early game depending on who you are. Try to plan ahead how you want to set up your divisions, as you won't be able to afford too much trial and error.
  • A good way to get XP while at peace is to train divisions, and send volunteers to other wars (which is dependant on ideology and World Tension). Training divisions costs equipment, but the combat bonus units get when they reach level 3 is invaluable, so you get dual benefits.
  • A Division is made up of Regiments, which are in turn made up of Battalions. Regiments are columns, so the more battalions a regiment is the more troops it has to cycle though, but generally speaking you want to be as 'deep' as you are wide, especially at the 20 Combat Width size. A 3X3 grid or a 4/3/3 set-up usually works.
  • In very general terms, Infantry provide a Division with HP, Defence and Organisation, while Armour provides the hitting power in terms of Hard Attack, Soft Attack (although infantry are good on this as well) & Breakthrough.

hoi iv 02 2

Combat Width

The basic combat width of a province (without any modifiers) is 80, which means each side can field up to 80 widths worth of Divisions (not account for any modifiers). In addition, an extra 40 width is applied per additional ‘front’. So if you’re attacking one territory from three, that’s a width of 160. In practice and sticking to the 20 width per division, you’ll be attacking with 4 divisions on the main thrust, and then two per flank. It’s worth noting that in this 3 v 1 scenario, only you get the extra width - the enemy has to stick with the 80 they get from their one province.

The reason you should stick to a combat width of 20 is down to how the game handles someone being ‘over’ the limit of a province. In simple terms, 4 x 20 = 80, but 4 x 21 is  84. This means an entire division gets sent to reserve resulting in you actually only attacking with 3x21, which is 63. If your enemy has stuck to 20 combat width, and assuming they've designed well, you’re at a 17 point disadvantage and will probably lose.

Support Vs. Line

Support Battalions are a key part of a division's make-up. You'll notice certain types, like towed Artillery & Anti-Tank guns, can also be put in as 'Line' Battalions as part of dedicated Regiments. The main differences between whether a battalion is 'support' or 'line' is:

  • Support slots don't change the speed of a division, which is set to the slowest unit. This means you can put support artillery with a motorized infantry division and it will still go as fast as the motorised units, for example.
  • Support regiments can be air dropped along with paratroopers, which allows you to give some much needed backbone to these divisions.
  • Support regiments require less equipment and manpower. But in the case of, say, artillery or AT, they also have less of an effect on the division's stats in comparison to a full regiment of the same type.

With this in mind, it's only really worth putting 'Line' versions of things like Artillery and AT on foot-infantry divisions. The speed penalty won't affect things as much, and you can give Infantry a lot more firepower. To keep within the 20 combat width limit you'll need to sacrifice an Infantry Regiment, but the trade-off in terms of HP and Organisation are worth it.

For armoured/combined arms divisions, generally you want to give them support battalions until you unlock the self-propelled tank chassis versions of Artillery & AT, so as not to be hit by speed penalties.

Combined Arms

While you can create divisions that work for a specific purpose, you generally want to mix things up. Depending on the role your division will be filling will dictate the make-up. As we mentioned above, Infantry provide a lot of HP, Organisation and Defence, while armour provide a lot of the punch.

Again TJ does some great videos talking in depth into general theory crafting for Infantry and Armour divisions:

There's also one for more motorised divisions, but it generally covers elements from the other videos, and until you get to mechanised I would personally advise against having all motorised infantry divisions because they cost 200 extra manpower per battalion, plus have severe terrain penalties. All you get in return is really the extra speed, but there are better combinations you can use.

A 'Light Armour W/ Motorised', for example, is a more rounded unit, but Light Armour has its own drawbacks - they cost as much 'Medium' tanks but aren't as good, some one school of thought is to wait until you hit Medium before adding tanks to divisions.

Make sure you check out this video on special forces design as well, including a dedicated Anti-Tank division. TJ also covers a land-based AA template, but we're getting conflicting reports over whether division-based AA actually has any effect right now. Personally, I never bother with it. Also worth keeping in mind is that Marine and Mountaineers are considered vastly superior to regular infantry due to the stat distribution (lower HP, but better organisation), so one option is to switch out all of your infantry for a specialist unit where possible.

We won't repeat too much of what TJ talks about, but there are some important lessons to always keep in mind when building and trying out new division templates:

  • Organisation is important. You'll run of organisation a lot sooner than you'll run out of health, and you'll lose 99% of battles due to low organisation.
  • Engineer and Recon support battalions are auto-include. If you've got motorised or amour, Maintenance is also a must, with Field Hospital being good for infantry divisions. If you're fighting outside of mainland Europe, Logistics can also be a life saver.
  • Signalling support is a secret weapon – use it more.
  • You'll want separate Divisions for attack and defence, although it's possible to design all-rounders as well. Generally Infantry are better on defence than they are on attack, but Mechanised Battalions change this dynamic some-what.
  • Standard Division templates for Infantry is 4/3/3, same for Infantry. Working towards the 20 Combat width, you then add and subtract other Battalion types from there. E.G., 3/3/4 Tank/Tank/Infantry (Motorised or Mechanised).
  • With regards to trying to fight armour, a single AT battalion/support AT per division is enough at a minimum: "A division's piercing is equal to 40% of the highest piercing in the division plus 60% of the weighted-average piercing of all battalions in the division" - HoI4 Wiki  

Final Thoughts

There are exceptions to all the things above – terrain, who you're fighting, the production capacity of your nation, research... these will all dictate or otherwise change what your 'optimum' regiment builds will be. You won't need much AT fighting against China, but you'll want a f***ton for Russia. The mountains of Italy are going to be problematic for armour or combined arms divisions, so the Mountaineer special forces troops will shine here. Also, we're told to avoid mud at all costs, apparently.

If you've yet to dive into the game, don't forget to check our our review of Hearts of Iron IV, which James split into two parts covering the civilian and military aspects. For my part, I think it's infinitely more accessible than Hearts of Iron III was, but still suffers from the peculiar problem of the planning and preparing for war being more fun than fighting the war itself. Still it's worth getting and will only get better over time, so for now at least consider yourself armed and ready for whatever is thrown at you.



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