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17 Pro Tips For Hearts Of Iron 4

Tips, tricks, and strategies that will have you playing Hearts of Iron 4 like a seasoned pro.

Like most games developed by Paradox Interactive , Hearts of Iron 4 may seem intimidating to a beginner. Leading a country through the 20th century's greatest conflict is no easy task after all. One bad mistake can lead to certain doom for a nation that isn't careful. Myriad decisions, both large and small, need to be planned in advance in order to avoid catastrophic failures.

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Knowing the keys to success before starting the game can help immensely. Hearts of Iron 4 possesses many layers. Coordinating those layers, especially in the midst of war, can often be difficult. However, with the right information in hand, conquering Hearts of Iron 4 can become less of a headache and more of a breeze.

Updated October 24, 2022 by Mark Hospodar: Hearts of Iron 4 recently released its latest expansion, By Blood Alone. This DLC focuses primarily on Italy, which got a much-needed revamp to bring it on par with the other major nations. An Aircraft Designer was also introduced, allowing players the opportunity to experiment with different plane designs.

With every new DLC and update, Hearts of Iron 4 becomes a more complex game. Since the game continues to evolve, players could always use a few new tips to reflect the updated meta. As such, this list has been expanded to include several additional pieces of advice.

17 Guard The Coasts

One aspect of the gameplay that many beginners tend to overlook and pros never ignore is coastal defenses . The attention this task entails obviously depends on which country the player is controlling. Landlocked nations need not worry about this problem.

Any country occupying a coast needs to implement some form of defense sooner rather than later. Unguarded shores easily invite enemy naval invasions . Build plenty of coastal forts and garrison the perimeter with second-line troops . Don't feel the need to construct a colossal chain of defenses. Even modest preparations can defeat enemy amphibious assaults.

16 Build A Variety Of Ships

When playing as a major nation, it's vital not to neglect the navy . After all, why throw away a helpful resource? The key to any proper naval buildup is variety . New players learning the ropes may be tempted to just focus on one type of ship. However, that strategy isn't always very efficient.

A proper task force meant to engage the enemy should contain a healthy variety of ship types. Veteran players all have their preferences, but a good composition to aim for is around 4:1 . In other words, there should be 4 screening ships for every 1 capital ship . Here's the breakdown of what constitutes screen and capital ships:

Screen Ships

• Light Cruisers

Capital Ships

• Aircraft Carriers
• Super Heavy Battleships
• Battleships
• Battlecruisers
• Heavy Cruisers

The reason for this variety is that each ship type has its own strengths and weaknesses. A task group only composed of one ship type can be outmaneuvered/outgunned by a superior enemy navy. A variable collection of ships, on the other hand, is ready for anything. In addition, submarines can be grouped separately to form "wolfpacks" to terrorize enemy convoys.

15 Close Air Support Is Essential

When it comes to deciding where to allocate military factories, players should never neglect close air support (CAS) . Close air support directly aids the player's ground troops in combat by inflicting damage on enemy forces and also provides a bonus to Breakthrough and Defense.

Players will still need to produce enough fighters to defend their CAS, but focusing on the latter should ultimately be the priority. Building radar stations will also increase the effectiveness of all aircraft in range. With the new Aircraft Designer introduced in the By Blood Alone expansion, fans can make their CAS even more effective by experimenting with the different aircraft modules.

14 Train Special Forces According To Your Needs

In the race to churn out as much infantry and guns as possible, it's easy to forget about Special Forces units. Special Forces come in three varieties: paratroopers , marines , and mountain troops . To maximize the efficiency of these troops, it's best to look at the map and plan ahead. Play to each unit's strength and watch them go to work.

Let's use a naval invasion of Great Britain as an example. A German player will want both air and naval superiority over the English Channel (use that variable navy!). Marine battalions may want to secure the ports in preparation for the arrival of the main army. Paratroopers can also be dropped behind enemy lines to cut supply routes and hold major cities.

In this example, mountain infantry will not be very useful overall due to England's terrain. It's important to remember that players are limited to the amount of Special Forces units they can train . A cap limit is instituted, whereby Special Forces can't exceed more than 5% of the player's total battalion strength. As such, don't waste resources on training units you won't need!

13 Occupation & Collaboration

Occupation is now a more complicated endeavor in Hearts of Iron 4 than it was at the time of release. Players hoping to directly occupy every single territory they conquer are going to have to invest extra time and resources to make sure it's secure.

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A territory that's successfully occupied will yield more resources and factories for the player. However, clamping down on resistance effectively is essential. Otherwise, habitual sabotage by the angry populace won't do the player much good. A worthwhile alternative involves setting up collaborationist governments . Although players won't directly administer the territory, the headaches of collaboration will be passed on to a semi-independent puppet government.

12 Invest In The Intelligence Agency

Utilizing one's Intelligence Agency effectively is yet another handy tool in a nation's repertoire. There are quite a few different avenues players can invest in, however, it's useful to decide ahead of time what kind of spy agency a player wants.

For example, if the player knows that they'll be occupying a lot of territories, it's beneficial to focus on the Defense branch. This specialization grants bonuses to anti-partisan activities and makes one's operatives more effective at rooting out resistance. As with all aspects of managing a country at war, the key is to play to one's strengths and stick with them .

11 Unlock Those Extra Research Slots

Research is vitally important in keeping pace with other nations in Hearts of Iron 4 . Among other things, research makes industry more efficient and combat units more deadly . The faster a country can conduct its research the more of an edge it will have over its enemies.

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Large, more developed countries tend to start with three or four slots already unlocked. Small and less developed nations only start with two, thus suffering from a disadvantage. Regardless of the initial count, smart players should always prioritize National Focuses that grant an additional slot . Outproducing and outgunning one's opponents ultimately result in victory and research serves as the linchpin.

10 Always Prioritize Production Technology

Now, what to do with all those research slots? Technology that benefits the military should never be neglected, but neither should production. Efficient production is imperative for keeping those tanks and planes rolling off the assembly line in short order. Research plays a key role in maintaining that efficiency .

At least one research slot should always be kept open for an industry technology. Playing as an Axis country , it's typically a good idea to choose the Dispersed Industry tree considering the threat of being bombed is quite high. Allied countries, like the United States, can get away with Concentrated Industry. In addition, always prioritize Production, Construction, and Fuel/Rubber technologies whenever possible to stay ahead of the curve.

9 Save That Fuel

20th-century warfare cannot be conducted without fuel. Nearly every unit in the game requires some degree of fuel, whether it be tanks, half-tracks, artillery, ships, or planes. If a nation's entire fuel reserves are depleted , units will still move but will start to suffer massive combat and speed penalties .

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As such, players always need to keep an eye on their fuel levels. Building synthetic refineries help, but fuel silos also need attention . Larger fuel silos mean larger amounts of oil that can be stockpiled for future use. Invading and occupying countries with large amounts of oil is also a helpful strategy. Don't let those tanks run dry!

8 Keep Training The Troops

Although there are diplomacy mechanics in Hearts of Iron 4 , World War II will eventually break out at some point. A nation's military is going to play a pivotal role when it comes to either victory or defeat. Whether or not a player's military is already large or small at the start of the game, more is going to be needed regardless.

Starting in the 1936 bookmark is favorable considering it gives the player about four years to build up their forces. Infantry and artillery are vital , but tanks also need to be given some early consideration if practical. When upgrades are made make sure they go to the principal front-line troops that conduct most of the fighting . Garrison units don't need all of that fancy new equipment.

7 Exercise Those Troops

Countries that start the game with significant military forces (like Germany) should never be kept idle. Likewise, newly trained divisions should never just sit on their hands waiting on the front line. Assuming there is no imminent danger, land units should conduct military exercises . The same holds true for air and naval units as well.

Exercising consumes equipment, which can potentially slow down the training of new units and rolling out upgrades. Nevertheless, units that exercise will eventually reach the "Regular" experience level, making them more deadly on the battlefield. Exercising also accrues a small amount of Land, Air, or Navy Combat Experience , allowing for additions to be made to the divisional templates.

6 Consider Terrain When Deciding Combat Width

The old debate regarding the pros and cons of 20 vs. 40 combat width is no longer applicable. The optimal combat width of a division isn't a cut-and-dry affair. Deciding on the best combat width for divisions now hinges predominantly on the terrain as well as the Reliability and Organization stats.

Some terrain types are better suited for smaller divisions, while others cater to larger formations. A player's chosen nation will play a role in this decision. For example, Japan and the United States will do a lot of fighting in the Pacific, where jungle terrain is common. Conversely, a country like Germany won't have to do much fighting in the jungle. This guide is extremely helpful for giving players a better idea of where to focus their efforts regarding optimal division templates.

5 Bank Some Extra Political Power Early

Political Power acts as a sort of currency in Hearts of Iron 4 . Spending Political Power is necessary when a player wants to perform an action such as changing a law or appointing a new advisor . A nation accrues political power gradually, but there exist other factors that can help speed up the process.

Generating large amounts of Political Power early can be extremely beneficial. Appointing an advisor that grants a bonus to Political Power accrual is a great first step. With more Political Power, more advisors can be appointed, which will benefit other sectors of the economy as well as war production. Draft and economy laws can be changed faster to a more war-centered footing , giving the player an edge over his opponents. There's no such thing as too much Political Power in the early game.

4 Get On A War Footing As Quickly As Possible

World War II is going to erupt whether the player likes it or not. Being unprepared usually results in getting steamrolled by a tougher neighbor . Luckily, players have the benefit of hindsight when it comes to World War II. They have until about the start of 1940 to get their houses in order.

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Having extra reserves of Political Power can really come in handy here. Moving towards a war economy should be done at the player's earliest convenience to scale back consumer good consumption. Tougher conscription laws also need to be passed so that manpower doesn't become an issue. Appointing a political advisor that increases a nation's war support can be beneficial when trying to enact these changes.

3 Go For The Encirclement

When it comes to defeating enemy forces, encirclement is the ideal scenario . Enemy divisions cut off from supply and fuel can't last. To achieve impressive encirclements, players may want to consider producing a few armor divisions with enough Breakthrough to overcome an enemy's Soft Attack.

Players may also want to consider that their tanks have enough Piercing to neutralize enemy tanks. By the same token, players should ensure the Armor value of their tanks exceeds their enemy's Piercing capabilities, although these considerations tend to be more applicable to multiplayer. With enough tanks to make a breakthrough and enough CAS in support, fans will be able to make substantial gains on the battlefield against the AI.

2 Prioritize Military Factories

Players have two basic choices when it comes to factories: civilian or military . Civilian factories increase the speed of construction and can also be used for trading with other nations. Military factories, on the other hand, produce all the necessary war material needed for the army.

In the end, military factories are going to have to take priority . Pumping out the vital equipment needed to win a war makes or breaks a campaign. This holds especially true whenever playing as a country where time is of the essence. Build enough civilian factories to fulfill the basic needs of trading and construction, then move forward with the military buildup.

1 Don't Forget To Trade (To Some Extent)

Trading in Hearts of Iron 4 is a pretty straightforward process. Players can give up some of their civilian factories in exchange for the resources they may need. Resources, like oil and rubber, play an important role in production. Not having enough resources imposes a penalty on production in certain cases .

Thus, it's a good idea to have some extra civilian factories so some trading can be accomplished. However, some deficiency in resources is still okay, even with the mild penalty . It's more important to use the civilian factories to construct other things one's country may need. Just keep things above water and don't feel the need to go overboard when it comes to trading.

Hearts of Iron 4 is currently available on PC.

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• HOI4 Console Commands
• Research_on_icon_click Command

HOI4 Research_on_icon_click Command

General information.

This command will instantly research any technology when its icon is clicked in the technology tree. This command is also known as the 'instant research' cheat.

This command can be toggled off by executing it a second time (it is a toggle command). You can research all technology with the research all cheat .

research_on_icon_click

The only way this command can be executed. This will toggle (enable or disable) the research on technology tree icon click feature.

• Hearts of Iron IV

When is it worth researching with an "ahead of time" penalty?

• Thread starter Gort11
• Start date Jan 4, 2017

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Field Marshal

• Jan 4, 2017
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I basically never research ahead of time - it feels like I'm "wasting" research days, even if it means I research something less important instead. In what situations have people found it worthwhile to research technologies ahead of time, despite the penalty, or by cleverly using national focuses and other effects to reduce the ahead of time penalty?  

I will sometimes research 1939 Inf Equip a little early so I can start producing it before WW2 breaks outs on Historical Focus. If you are every going to do a tech early make sure to save up 30 days of research progress first, because that's a month of ahead of time penalty lost without loosing any tech progress.  

Sleight of Hand

Retired modder.

Capital ships, due to how long it takes to build them and the advantage it then gives you.  

Secret Master

Covert mastermind.

Panthers in production by the end of 1940? 1944 Light Fighters and 1944 strategic bombers in production by early 1941? Production and IC techs in place before the year they become available so you can produce those Panthers or planes? If you are using NFs properly, researching ahead of time can be a real boon. Note that even if you get a -50% reduction in research time, researching something three years in advance takes a long time. But the difference in performance is quite noticeable. (The cost in resources is as well.)  

Lt. General

And definitely most of the production techs youll be researching ahead of time, other than construction. Ill usually give it 6 months or so between Concentrated II and Prod.Eff II before I start on the 1940 versions in 1938. Then ill finish the '41s in mid/late 39. Im always finished with the '37s before Jan '37. ~33% extra production out of your Prod.Eff and +20% output for concentrated are some of the most powerful technologies in the game. No matter who I play im getting those ahead of time, every single game. A couple people with the -50% industry focuses, ill use that to cut down the time of the '41 concentrated to get it even sooner, in late 38. Depending on who I play, I might get Mech, Medium Armor, or Arty II ahead of time, simply because they are expensive and theyre a huge boost over what you had before, so getting them early is crucial. USA, Italy and Japan, I might consider researching ships ahead of time because of the advantage they bring. Getting early Carrier IIIs or Super Heavy IIs can be really powerful depending on what your opponent is doing.  

First Lieutenant

Panzer III tanks for Germany is one. It's a 1939 tech with a base cost of 200 days that you can research starting in June 1937 for only 168 days using an armor design company and the 100% ahead of time penalty reduction from the Treaty with USSR national focus. 50% bonuses can also be used to blunt the ahead of time penalty- I've used those on other armor or air models, but not too far ahead. I'm curious about when certain industry, say concentrated industry for +20% output, might make sense to go a few months early. Not the 37 one since why rush building more 36 hardware. But maybe the 39 or 41 versions. But I haven't tested that out. But in general, I'm with you on trying to avoid penalties. There's so many techs and so few research slots / years so you want to maximize what you do. For reference, I just posted on another tip on switching days that can help a bit on earlier research: https://forum.paradoxplaza.com/foru...ogy-swapping-another-min-maxing-trick.992705/  

Krafty said: And definitely most of the production techs youll be researching ahead of time, other than construction. Ill usually give it 6 months or so between Concentrated II and Prod.Eff II before I start on the 1940 versions in 1938. Then ill finish the '41s in mid/late 39. Im always finished with the '37s before Jan '37. Click to expand...

Krafty said: And definitely most of the production techs youll be researching ahead of time, other than construction. Ill usually give it 6 months or so between Concentrated II and Prod.Eff II before I start on the 1940 versions in 1938. Then ill finish the '41s in mid/late 39. Im always finished with the '37s before Jan '37. ~33% extra production out of your Prod.Eff and +20% output for concentrated are some of the most powerful technologies in the game. No matter who I play im getting those ahead of time, every single game. A couple people with the -50% industry focuses, ill use that to cut down the time of the '41 concentrated to get it even sooner, in late 38. Depending on who I play, I might get Mech, Medium Armor, or Arty II ahead of time, simply because they are expensive and theyre a huge boost over what you had before, so getting them early is crucial. USA, Italy and Japan, I might consider researching ships ahead of time because of the advantage they bring. Getting early Carrier IIIs or Super Heavy IIs can be really powerful depending on what your opponent is doing. Click to expand...

• Jan 5, 2017

Krafty- Looking at your notes, I'm not sure I'm reading it right. I can't see how to replicate. Here's my most recent early plan. Bank 30 means I transfer 30 days saved tech from a previous placeholder. For example, I start Concentrated Industry I in June 36 with 30 days already saved even though the prereq 1936 Basic Machine Tools doesn't finish til near end of May. I also get a Industrial Concern on 3/11/36 for a 10% reduction in industrial techs. This is as early as possible using Rhineland PP bonus. Date Tech Slot 1 Tech Slot 2 Tech Slot 3 Tech Slot 4 Jan 36 1936 Electron Mech (-2% tech) 1936 Basic Machine (+5% max prod eff) 1936 Construct I placeholder (typically 1936 Maint, but I use to hold 30 days) Apr 36 placeholder to bank 30 1936 Mech Compute (-3% tech) (w/ bank 30) Jun 36 1936 Con Industry I (w/bank 30) placeholder to bank 30 Jul 36 1936 Excavate I (w/ bank 30) Land Doc #2 Nov 36 placeholder to bank 30 placeholder to bank 30 Dec 36 placeholder to bank 30 Jan 37 1937 IND 2 (w/bank 30) 1937 Con Ind 2 (w/bank 30) 1937 Construct II (w/bank 30 & 50% bonus from focus) Feb 37 1937 Excavate II (w/ 50% bonus from focus) Mar 37 finish IND 2 finish Excavate II May 37 finish Con Ind 2 Effectively, I start 1937 Con Ind 2 on 12/1/37. I could move that up to 11/1 (or 10/1 with banking 30 days), but it still wouldn't finish until March or April 37- a month or so early. Effectively, I start 1937 IND 2 on 12/1/37. I could be moved up even sooner to end of May 36, and it would take 208 days instead of 128 and finish by 1/1 instead of 3/31. So starting six months earlier would get the 10% prod efficiency increase ~ 3 months earlier. How are you able to finish 1937 Con Ind 2 before 1/1/37? Are you on another country who has a industry tech bonus available from a focus? Or is there something else I'm missing? 1939 IND 3 (prod eff +15%) and 1939 Con Ind 3 (output +20%) seem more attractive to rush since they'd apply to more factories at higher efficiency producing better kit. 1941 even more so. When do you tend to start those? mid-38 for the 39s? When for the 41's? You mentioned 39- are you taking > 1 year of penalties on them and tying up two research slots? Thanks- Marty  

csgdzjtpxj said: Panzer III tanks for Germany is one. It's a 1939 tech with a base cost of 200 days that you can research starting in June 1937 for only 168 days using an armor design company and the 100% ahead of time penalty reduction from the Treaty with USSR national focus. 50% bonuses can also be used to blunt the ahead of time penalty- I've used those on other armor or air models, but not too far ahead. I'm curious about when certain industry, say concentrated industry for +20% output, might make sense to go a few months early. Not the 37 one since why rush building more 36 hardware. But maybe the 39 or 41 versions. But I haven't tested that out. But in general, I'm with you on trying to avoid penalties. There's so many techs and so few research slots / years so you want to maximize what you do. For reference, I just posted on another tip on switching days that can help a bit on earlier research: https://forum.paradoxplaza.com/foru...ogy-swapping-another-min-maxing-trick.992705/ Click to expand...

Yeah im using two research slots. Construction 1, Machine Tools, mechanical computing, ??? to start. Then Concentrated, Prod Eff. Then Concentrated, Prod Eff after 30 days of saving after the first two are done. Industrial concern. Then other focuses, eventually getting the industry 50% (tho not all nations have that readily available and in mp priorities might shift), then Con + Prod Eff. If Eff is already maxed, I use the bonus on that, if not, concentrated. I dont usually get Construction 2 or Factory repair until just before or just after the war starts, and sometimes not at all as Germany. Two slots are always on industry, though ill generally get heavy SPGs with one slot at 47 days I think, to let the higher cost of Prod Eff die off to about 1.7 years ahead of time, before saving another 30 days to start it when it takes less than 300. Any time industry is less than 300 days, im starting it immediately. Though if its 450 or so and will still be finished before the actual date of the tech, ill do that too. I cant think of any two techs that cost 225 days a piece that id rather have over industrial techs. It works well if the USSR player is known to not do tank and molotov. You just brute force the industry to have more than them and get logi bdes to not be over supply. This is mostly MP buy basically anything works in SP. Hungary is going to build my good planes so I dont need fighter IIs that early. I wont have mediums, so I dont need to put slots on that either. I get Heavy SPGs, and as many 12km speed divisions as I can get, and double down on arty+inf divisions. Also with this if you want, you can start with basic rifles, throw out a ton of troops, and get Anschluss, Rhineland and Chechs pretty quickly, maximizing how much those bonuses do for your overall industry. That wont work in MP tho because of WT. Once you have mainland europe before 40, and your 40 industrial techs are already done, you more than rival the combined allies and WT is just starting to get up to 70-80. You can build all the planes or whatever else you skipped then, and still conquer the world. If you're in MP, you have allies that filled your gaps. Hungary built your planes, Italy has your navy, Romania has your paratroopers, it drastically cuts down on what you need to research so you can devote two slots continually to industry, or waiting for industry. Once you have europe, you're in a much, much better position industrially than if you had simply built an elite army first. You can easily beat the AI and player France with an out of date army.  

Comrade110 said: You can get King Tiger (1943 heavy) before 1940, about november 39 or so. Tell me, who can oppose such a force ? Click to expand...

Walderschmidt

It would be lovely if you could chain research so that you don't have to micro (set up an automatic research follow up, whereby once a tech slot finishes one technology, it automatically gets on a second tech that you designated ahead of time). Would be nice if you could do this to national foci, as well. Wald  

Secret Master said: Bomber Command? Click to expand...

Secret Master said: Panthers in production by the end of 1940? 1944 Light Fighters and 1944 strategic bombers in production by early 1941? Production and IC techs in place before the year they become available so you can produce those Panthers or planes? If you are using NFs properly, researching ahead of time can be a real boon. Note that even if you get a -50% reduction in research time, researching something three years in advance takes a long time. But the difference in performance is quite noticeable. (The cost in resources is as well.) Click to expand...

deckard6 said: I will sometimes research 1939 Inf Equip a little early so I can start producing it before WW2 breaks outs on Historical Focus. If you are every going to do a tech early make sure to save up 30 days of research progress first, because that's a month of ahead of time penalty lost without loosing any tech progress. Click to expand...

Krafty said: At least everything but Space Marines. Hence them being banned in like, every MP game ive ever played since August. PDX could fix space marines by not allowing Heavy Tanks to EVER (EVER!!!!) get river crossing bonuses. Theres no legit reason why engineers or marines are going to make KV-1s into Riverine Battleships. Click to expand...

Nasr said: Panthers by end of 40? You're not doing it right. Easy to get Late 39 - Early 40. Click to expand...

Hearts of Iron IV

Originally posted by spike2071 : I always look for a focus, tech, or something that gives 50% off the research time of what you want to research ahead of time. I don't think tanks are worth researching ahead of time, but give it a shot and see. I usually rush fighters, as I think they're worth their weight in gold.

Originally posted by |H|H| Fr3ddi3 : Against AI, it's not worth it. The AI can't keep pace with you to offer up a challenge. Against a Human, it can be highly beneficial depending on strategy. Panthers by 39 for the war with Russia is a common tech path for Germany players.

Originally posted by BloddyK : Btw you should never take industrial companies or arty/infantry -10% research time

Originally posted by direweaseltjw : In the case of German Armor, there are national foci which will very much speed up your ability to get advanced armor ahead of time. If you make the technology deal with the Soviets, you will recieve (among other things) a 100% penalty reduction in PZIII research. In other words, you can research it in 1936 as if it were 1939, with no early research penalty. You will also get a 50% bonus on another armor (the PZ4), so it makes the early penalty on it much less painful. Using those, it is quite possible to have PZIVs in full production by 1939. There are other similar cases where a well used national focus will get you way ahead in a critical tech. For instance, when playing as the Brits, I have 1944 fighter planes going before the war starts.

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However, the mountings above the portrait are additional slots for customizing the class, and contain no mandatory elements. These are divided into three sections for the ship -- front, middle, and rear, with up to two front and rear slots and three middles ones. As an example, the Early Destroyer Hull only has one middle and one rear slot above-portrait, but the 1940 Destroyer Hull has a middle, rear, and front.

Exactly what can go in the optional slots also changes from ship class to ship class. Cruisers and battleships can only mount main guns or AA in their front slots, but destroyers can mount depth charges in theirs (as the 1940 technology bracket also unlocks the Depth Charge Mortar). A wide variety of equipment exists that can produce highly specialized ships.

• 1.1 Destroyer hulls
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