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How to Play: Hearts of Iron IV

Posted: Tue May 31, 2016 12:22 pm
by aphrochine

This thread will be for linking guides, references, wikis and will house discussion on how to play HOI4. I'll try to compile all things here in the OP.

(note: some content may not be available until release)


HOI4 Guides (paradox)
Battle Planner
Politics (not a "how to", general info only)
Division Designer
Air Force Management

War College Video Series: ... 9K-hT94a2s

Let's Play
Quill18 as Italy ... S1hvUIflCL
Arumba as Germany ... ELL5bQFcwC
DDRJake as El Salvador ... C8PiszcvRC



Re: How to Play: Hearts of Iron IV

Posted: Mon Jun 06, 2016 9:13 am
by aphrochine
Production Tips & Info

Hey guys, so here is some information about production.


The firsts thing, which is wildly different than any other HOI, is that you no longer "produce" divisions. Instead you produce equipment, which when married with manpower, creates divisions. Equipment encompasses all things you will use to fight a war. In a production sense, battleships are even equipment.

Equipment is produced via "lines". Each Line can have up to 15 Factories or Naval Yards assigned. Each piece of equipment has it's inherent IC cost, and production speed is based off of the IC cost. Each factory produces X amount of IC, which varies with technology. So the amount of IC applied to a line each day, is determined by the number of factories * factory IC output. When enough IC has been applied, equipment will roll off of that assembly line.

All equipment consumes Resources. Resources are available from a "per day" amount of resources. There are no stockpiles any longer. Unused resources are considered to be used somewhere else. When a production line is suffering from insufficient resources, it's IC efficiency is reduced by the amount of missing resources.


A Fighter might need 1xAlum, 1xRubber, 1xOil per factory. We are using 5 factories, for a total need of 5 each of Alum, Rubber & Oil. Let's say we are short 3 rubber and 3 oil. So we have 5/5 Alum, 2/5 Rubber and 2/5 Oil. So we are missing 40% of our total resources. Our efficiency is reduced, and we only receive 60% of our IC for that Line.

Reinforcements, Upgrades, Constructions & Stockpiles

When equipment is produced, except for Ships, that equipment is sent into one of 4 areas:
  • Replacements: Units which are under their ToE, will request Reinforcements.
  • Upgrades: Units who have old equipment, will request Upgrades for the newer, shinier stuff.
  • Construction: Units which are currently being trained will request equipment until their ToE is full.
  • Stockpiles: If the 3 needs above are met, the equipment will go into a stockpile and wait for it to be needed.
There are prioritization levels for equipment.

For Land:
Deployment Screen: Prioritize Replacements, Upgrades and individual deployment groups.
Theaters Window: Set priority for individual theaters.
Division: There is no method of prioritization that I'm aware of for the division level.
Template: Templates can have a priority set, which is a sub-priority of the above priorities. This applies globally.

For Air Wings: Priority is set at the Air Wing level, from the airbase window.

Division Training & Deployment

How you "build" a division is completely different than previous HOI games. In HOI4, you must actually Train your divisions. This is done from the deployment screen. You choose a Template, an determine how many you want to train.

Training is capped, however, based on how much equipment the Division has received. Last I checked, I think a division can only train about 5% or 10% higher than it's current equipment level. A division is automatically deployed at 100% training, and will then appear on map.

NOTE: You can no longer withold units in some magical queue. Once production is finished for Land and Ships, they are popped out onto the map, and may be attacked.
  • Deployment Tips:
  • Because training takes time, and because you do not need to be full ToE to begin training, it's highly advisable to begin training divisions even before you have all of the equipment.
  • Always selected where produced ships are to be deployed, this is done in the Production screen. You might not like where the AI plops them down under "Auto".
  • Deploy units early if needed. While units which are not fully trained suffer combat penalties, they are still units and have Soft Attack, Defense and Org. This also goes for under equiped units.
  • Manpower does not "grow" like it did in other HOI games. Manpower primarily comes from the % of the population your conscription laws draw from. So do not use all of your manpower for deployment. Keep appropriate amounts in reserves.


Production comes from 3 primary factory types
  • Civilian Factories (CIC): This is the "base" of your industrial might. The more Civilian Factories you have, the more you can trade for, and the more you have to produce other things, like Military Factories and Naval Factories.
  • Military Factories (MIC): Used to produce Land and Air equipment. Build as many as your industry and resources can handle.
  • Naval Dockyards (NIC): Obviously used for ships only.
Consumer Goods is represented in HOI4 as a % of Factories not available to the player for construction. Democracies, and the US especially, suffers from very high Civilian Factories. An important note here is that Military Factories and Civilian Factories are totaled to create your Consumer Goods factory number.


Military: 20
Civilian: 30
Consumer Goods: 50%
Consumer Goods Factories = 25
Available Civilian Factories: 5 (30 - 25)

So if your Economics Law demands high Consumer Goods, be wary of Military Factory Spam. It's probably better to build Naval Factories, and some additional Civilian Factories until you can unlock better Economic Laws.

This being said, the most important production queue in the game, is your Construction Queue. This uses your available Civilian Factories (after Consumer Goods), to build more stuff...primarily more Factories.

Factory Slot Limit:

Each state has a limit on how many slots you can build stuff on. This is based off of the type of state, and modified by your Industry Technology level. This creates a theoretical limit to the size of each nation's industry. Keep that in mind for long term planning.

Strategies: Civilian Factories is more expensive than Military Factories and Naval Dockyards. This makes it not always appropriate to build more CIC. Building up more IC can take a longer time. Aggressor nations often use war to expand their CIC base, which building MIC mostly. Democracies, with fewer early war options and higher CGs, will often build more Naval Dockyards to produce larger navies and project, while building additional Civilian Factories.

Oil & Rubber:

These are hands down the most difficult to get resources for many nations. Production of these resources is largely confined to the USA and ENG, with some additional production by other minors and SU. Luckily, a player may research and produce Synthetics plants, which product +5 Oil and +2 Rubber per level. Note that Synth plants cost as much as Civilian Factories, and since you can trade +8 of a resource with 1 CIC, it's ALWAYS more efficient to build a Civilian Factory and trade, than it is to build a Synth plant. Synth plants should be used after war start, and trading options are no longer available.

Rubber: 90% of the worlds rubber production comes from Malaya and the DEI. Be aware of this. Rubber is only produced at +2 per Synth and will largely be controlled by either UK or (later) Japan. Plan accordingly. Fortress Malaya is a solid strategy for UK, just for holding on to Rubber for as long as possible.

Oil: It is more likely to satisfy a high Oil need with Synth's for nations like GER or ITA. Add in access to Romanian Oil fields and it's still possible for a successful GER to have all/most of it's oil need satisfied.


Trading is different in HOI4. Now, each nation has a Trade Law setting which determines the % of produced resources which are traded out to the market. This market trade is completely out of the owning players hands. If GER wants 80 Oil from USA, it gets it. The only way to adjust this is through consumption, war, changing trade laws or embargoes.

Note that each potential trade partner has a trade relations value. The higher the value, the more likely that nation is going to get all of its requested resources if competition arises.

Re: How to Play: Hearts of Iron IV

Posted: Wed Jul 27, 2016 12:12 pm
by aphrochine

Re: How to Play: Hearts of Iron IV

Posted: Thu Jul 28, 2016 8:57 am
by Altaris
These are handy. Thanks!

Re: How to Play: Hearts of Iron IV

Posted: Thu Aug 18, 2016 12:25 pm
by aphrochine
Updated with the War College series. Overall very good.

Re: How to Play: Hearts of Iron IV

Posted: Fri May 25, 2018 7:40 pm
by Altaris
I think we should majorly resurrect this thread. Start putting lessons learned from the games played and such, as a central place we can all learn from.

I'll start us off.

Port Protection
In our Game 3, I lost the advantage of a strong position by too weakly and inefficiently guarding my ports. HOI4 does a much better job of simulating coastal defenses and invasions than earlier iterations, you really need more than just the ports themselves defended to hold off a determined naval invasion. For key ports, consider having 80 width (at least 40 width) infantry divisions dug in and waiting, and it's important to have other units fanned out in the coastal provinces neighboring it. Otherwise, the enemy can just land along 3-4 beaches, flank your port, and have a bunch of additional combat width to wilt your defense down. A mobile reserve of light tanks/motorized would be good to have on hand as well for quick reinforcement in areas with multiple beaches.

Everything except Marines gets pretty hefty penalties to their attack values when attacking a beach. This includes adding firepower to a Marine unit via artillery brigades or such (though not from support companies - an important distinction). These penalties go away once the units are landed though, so a smart naval invader is going to try to capture and secure beaches adjacent or close to a port, encircle it, and attack with as many units as possible to get maximum flanking combat width and overwhelm the position.

There's two ways to try and counter this. First, you can contest the beach-heads, but this is expensive in terms of manpower needed, since there are so many beaches. However, contesting beach-heads can also be done using pretty much straight infantry, at least to hold the position while a mobile reserve can get in to reinforce it. Second option is to beef up the port itself and hope it can hold out against an encirclement attack, depriving the naval invasion force from a point of supply and eventually forcing it into a supply attrition point of having to retreat or die of starvation.

The important aspect of both these approaches, you need a mobile reserve fairly close by that can help contest beach invasions, or help reinforce/avoid encirclement of a port if the forces land. The mobile reserve can be used to mask multiple landing points to maximize it's coverage, but it's important to have one and it be sufficient. I can safely say after Game 3 you will spend far less troops masking the beaches than trying to reform the line after a major naval invasion :)

Re: How to Play: Hearts of Iron IV

Posted: Mon May 28, 2018 11:54 am
by Altaris
Here's a link to a super-helpful listing of battalion costs and statistics:

It really pays to get an idea of what types of units you're going to have fielded, and how much they're going to cost, before the game starts. Once war breaks out, the time in-game that can be committed to reviewing builds is minimal, and it's often difficult to compile all the data from the UI alone, this can greatly reduce the number-crunching task.

There's also a link in this wiki to export the list to Excel.

Re: How to Play: Hearts of Iron IV

Posted: Mon May 28, 2018 1:00 pm
by harbringerxv8
As a supplement to Altaris' notes on port defense, it's important to note really just how important it is to have some form of strategic reserve. Breakthroughs are going to happen, one way or another, and there is basically no such thing as an impenetrable defense. When that happens, you need to be prepared with enough troops to either A) blunt the attack entirely or B) buy enough time for you to redeploy forces from elsewhere to fulfill A). As he said, light armor and motorized troops are the best for this type of task, given their speed. Infantry can accomplish this as well, but they will need to be deployed closer to potential breakthrough points, and as such are much less flexible.

Of course, as the attacker in this situation (as I was in Game 3), when faced with a heavy defensive position, it is always good to consider three-dimensional thinking. Altaris had level four forts behind the Dnieper River, stacked to the teeth with men and guns over about a 1,000 mile front. That is a very tough nut to crack, and I would have taken considerable losses against it in a direct assault. Always be looking for alternative offensive avenues to catch your opponent off guard. A surprise attack in an unsuspecting location with 10 divisions is often more useful than a well-planned but obvious attack with 100.

Re: How to Play: Hearts of Iron IV

Posted: Mon May 28, 2018 5:56 pm
by Altaris
I severely underestimated how difficult it would be to play a fluid defensive war. Especially at Speed 2, there's just not enough time to react across the entirety of the Russian front to multiple crises situations. This means, for practical purposes, there needs to be layers of troops so a German spearhead can't just break through one line and then cut off a force.

For Soviets, this means a huge number of infantry need to be fielded. They are the only units realistically cheap enough to deploy across this front and stack 3-4 regions deep.

Basically, for a 1 man show to run the Soviet Union, it needs to have enough defense in depth to withstand a few punches so a serious breakthrough gives enough time to react appropriately.

Initiative makes a huge difference in this game, Germans have it with their land doctrine. Key to Soviets is mitigating this advantage. Layers, and layers, and layers of bodies go along way towards this.

Re: How to Play: Hearts of Iron IV

Posted: Sun Jun 03, 2018 3:42 am
by Altaris
Researching some template builds, came across a really nice one.

Rocket Artillery allows you to build Rocket Artillery support companies, which stack with the regular Arty support companies (you can put both on one division). This essentially allows you to double-up your support artillery, which with the arty nerfs in WTT, is a much better return on investment IC-wise for soft attack than adding arty battalions. Also very important for things like Marines and Paratroopers, who need as much firepower without impacting their base function as possible, and tanks, which don't get a speed penalty from companies.

It is a 1940 tech, so not useful for the early war, but helpful nonetheless to know.

If you combine this with Superior Firepower doctrine, which gives a total of +50% soft attack to support companies, this becomes even better and puts the arty companies close to the firepower of a regular arty battalion. And for about 1/3 of the cost in equipment.

Could be a really good build for a low manpower, long front country like UK or Italy or Japan in the later war.

Re: How to Play: Hearts of Iron IV

Posted: Sun Jun 03, 2018 7:52 pm
by aphrochine
Rocket Arty damage is buffed by rocket techs, but the buff techs between rocket and tube are about the same once all completed.

Re: How to Play: Hearts of Iron IV

Posted: Mon Jun 04, 2018 9:06 am
by Altaris
Understood but my point is you can stack regular arty support and rocket support in the same division. With superior firepower giving each +50 percent that's close to 2 full sized batallion arty pieces without using combat width and about one third the equipment cost. that's pretty nice.

Re: How to Play: Hearts of Iron IV

Posted: Mon Jun 04, 2018 1:43 pm
by aphrochine
Altaris wrote:
Mon Jun 04, 2018 9:06 am
Understood but my point is you can stack regular arty support and rocket support in the same division. With superior firepower giving each +50 percent that's close to 2 full sized batallion arty pieces without using combat width and about one third the equipment cost. that's pretty nice.
I wasn't arguing, adding...

Re: How to Play: Hearts of Iron IV

Posted: Mon Jun 04, 2018 5:48 pm
by Altaris
It is a lot of research, though I think it might very well be worth it for the Soft Attack. That's pretty hard to come by in WTT.

Re: How to Play: Hearts of Iron IV

Posted: Mon Jun 04, 2018 10:36 pm
by aphrochine