This is intended as a beginner's tour of the interface and mechanics in Hearts of Iron IV. For more detailed information on the mechanics, including some of the detailed maths behind some of the computer's calculations, follow the links to the articles dedicated specifically to these concepts.
- 1 Starting the game
- 2 The interface
- 2.1 World tension
- 2.2 National information and development
- 2.3 Research
- 2.4 Diplomacy
- 2.5 Trade
- 2.6 Constructions
- 2.7 Production
- 2.8 Recruit and deploy
- 2.9 Logistics
- 3 Controlling your army
- 4 Controlling your navy
- 5 Controlling your air force
- 6 Supply
- 7 Special weapons
- 8 Winning the war
- 9 Tips to getting started
Starting the game
Once you start the game, you will see a menu with five buttons. The QUIT button closes the game. CREDITS will show you a list of everyone that worked on developing, producing and delivering Hearts of Iron IV. The most important buttons are the other three.
Single player is what you press if you want to play a game of Hearts of Iron IV by yourself. All other nations will be controlled by the computer. The Single Player menu allows you to continue or load previous games you have saved but not completed. This is also where the tutorial is.
It is highly recommended that you play the Tutorial. It will give you a quick run down
Press multiplayer if you want to play a game of Hearts of Iron IV online with other people. Up to 32 people can play Hearts of Iron IV at once. This menu will allow the host of the game to load a previous session that was not completed.
Press options to customize the sound and appearance of Hearts of Iron IV on your computer. You can adjust the monitor resolution, set your sound preferences, and other game details. The "game settings" in the first tab on the Options menu is very important.
Once you've gone through the basic setup, you will need to choose which scenario you want to play, and which nation within that scenario. You will then be in charge of that nation for the duration of your play session.
Choosing a scenario
Hearts of Iron IV has two scenarios - 1936 and 1939. Each presents a different challenge, and the scenario you choose will largely dictate what kind of game you will be asked to play from the opening.
The world in 1936
The 1936 scenario begins on January 1, 1936. The 1936 scenario is the one most likely to lead to alternate versions of World War II, since it starts with fewer alliances or wars to start. 1936 is the place you want to begin if you want to enjoy the organization and planning of an economy before the war opens. This scenario is more about laying the groundwork for your war plans, opening with a focus on factories, research and diplomacy.
The world in 1939
The 1939 scenario begins on September 1, 1939. Germany has consolidated its power in central Europe and is primed to attack Poland. If you want to play a game about World War II that will be more likely (but not certain) to evolve as the real war did, you should start here. This scenario is more about building, supplying and leading your armies.
Choosing your nation
Once you've picked your scenario, you will be shown a menu with the seven major powers to choose from (Great Britain, France, United States, Germany, Italy, Soviet Union, and Japan) as well as an option to pick Other Country. No matter which you choose, you will be shown a map of the world and giving an opportunity to change your mind. Then press play in the lower right hand corner.
The user interface of Hearts of Iron IV will be immediately familiar to veterans of Paradox strategy games. The left hand of the screen will be used to manage large national issues, alert tabs will appear at the top of the screen to warn you of things that need your attention, and the right hand side of the screen will be devoted to information about your troops. The very top border of the screen will include important summary information about the state of the game and the world.
Across the top left to center of the main play screen, you will see a row of numbers running from left to right.
- National unity
- A measure of the war-resolve of your country. A country with low national unity will surrender more quickly than one with high National Unity. National Unity is determined by National Spirit traits that can be assigned to certain countries (France, for example, starts with very low NU), but it can be modified through National Focus choices or recruiting government officials to modify it.
- Political power
- This is the amount of political capital your leadership has accumulated. You spend political power on completing national focus ideas, recruiting military and scientific advisors, changing trade and conscription laws, and some diplomatic actions. Each nation gets 2 points of political power per day, modified by certain traits, individuals, player actions or characteristics.
- The number of men you have available to create and reinforce military units. This is affected by a number of factors, primarily your conscription levels and number of units under construction.
- Three separate numbers, listing the military factories, naval dockyards and civilian factories available for new orders. We will deal with their roles in a future section.
- Army, Navy and Air experience
- As your units fight or, in the case of armies, exercise, they will gain experience. You can spend army experience in the unit designer to edit or invent land divisions. You spend naval and air experience on modifications for your ships and planes, giving them bonuses to speed, firepower, and so on.
- The number of convoys or transports you have available. Each trade you make for strategic resources will require allocating a convoy unit. Moving land units across oceans and seas requires an allocation of transports. You can increase the number of available transports by building new convoys in the unit production menu.
To the upper right of the screen you will see a glowing circle with a percentage below it, indicating the world tension. This percentage is the measure of how much tension is in the world. Some diplomatic and military actions, especially for democratic or neutral nations, require the world tension to reach a specific level. World tension is increase by historic events, declarations of war, and other hostile diplomatic actions.
National information and development
To the far left of the screen you will see your nation's flag. Click this flag to open a view of your national status. You will see a portrait of your leader, political support and parties, some active variables and factors for your nation, and three rows of items you can spend your political power on.
You will be prompted to choose a national focus for your country. It takes 70 days to complete a national focus, and it costs one political power point per day. National Focuses are similar to research tech trees in other games, except they are connected with choices your country is making about its direction. It may choose to, for the moment, focus on industrial growth, or, in the case of Germany in most games, push for expanding its borders at the expense of its neighbors. Some National Focus choices are mutually exclusive; the Soviet Union cannot be friends with both China and Japan.
From this menu, you can also spend political power on changing government laws or hiring political, military and industrial advisors. Most changes will cost a minimum of 150 political power, very powerful advisors may cost up to 250.
Laws and government
- Conscription law: affects how much manpower is available to your country
- Trade law: affects research speed, factory and construction speed and how many resources are available to be traded
- Economy law: affects how many factories are dedicated to consumer goods, manpower availability, and military production
You also have space for three political advisors you can hire to give you bonuses
Research and production
You can add a tank designer, ship designer, aircraft designer and material designer to earn bonuses to either production of the relevant weapon system, or affect its combat abilities.
You can also add an industrial concern and a theorist to improve certain types of research.
You can add a Chief of Army, Chief of Navy and Chief of Air Force to improve research or combat skills in the relevant field. You may hire up to three other members of your high command.
The gray button at the top of the screen marked with a beaker () opens your research menu. You will have three or four slots available to research particular technologies, but if you pursue specific national focus ideas you may unlock additional research slots.
There are eleven categories of research. Each nation starts with an historically appropriate level of technology and theory, depending on the scenario.
All the research trees (except for doctrines) are marked along an historical timeline. Researching a technology or unit before the historic date will take longer than it would if you researched it at or after the historic date. This penalty may be modified by pursuing certain National Focus ideas.
Infantry: researching better infantry weapons and different types of infantry divisions. This is where you will go to unlock mechanized infantry, paratroopers, marines, mountain troops and so on.
Support: researching support battalions that you can attach to your divisions. This is where you will find engineers, medics, mechanics, and so on.
Armor: research light, medium and heavy tanks, as well as variant tanks based on the chassis you unlock.
Artillery: researching artillery, anti-tank and anti-aircraft weapons.
Land doctrine: Most of the great powers will start with an initial land doctrine. You may change this, but all land doctrine paths are mutually exclusive. The land doctrine you choose will assign major combat bonuses.
Naval: researching more advanced warships, submarines and convoy/landing craft.
Naval doctrine: Some of the great powers will start with an initial naval doctrine. You may change this, but all naval doctrine paths are mutually exclusive. The naval doctrine you choose will assign major combat bonuses.
Aircraft: researching different types of fighters, attack planes and bombers as well as carrier borne variants.
Air doctrine: Some of the great powers will start with an initial air doctrine. You may change this, but all air doctrine paths are mutually exclusive. The air doctrine you choose will assign major combat bonuses.
Engineering: researching electrical engineering for radars (for detection) and computers (for research and encryption bonuses), as well as researching nuclear and rocket technology
Industry: researching means to improve the efficiency, productivity and resource extraction capabilities of your country.
The gray button with a hand ready to be shaken () opens your diplomacy menu. Here you will see a list of nations and a number of filter buttons to narrow down the list.
When you click on a nation you want to interact with, you will see a portrait of the leader, and a little bit of information about what the nation is up to. In the upper right corner of the menu, you will see a couple of tiny flags with arrows indicating the relationship between your two nations. There are a number of actions you can take in the diplomatic menu, provided you meet the requirements. Democracies are especially limited in their abilities to undertake aggressive diplomatic actions unless the world tension meter has climbed to a high enough level.
Hover your mouse over each option for a description of the diplomatic action and what conditions must be met.
The gray button with box and curved exchange arrows () opens your trade menu. You will see a number of tabs and columns listing the major resources available, what you require and possible trading partners.
There are six major resources in the game: oil, rubber, aluminum, steel, chromium and tungsten. These are used to help in the construction tanks, battleships, planes and so forth. Each new production line of a major weapon system will require a certain amount of resources. Though you can build these units without the necessary resources, your production will be much slower and less efficient.
Resources are found in certain locations on the map and are not evenly distributed. You will almost always have to trade for what you need.
To trade for a resource, click on the name of the country and move the slider to determine how much you are trading for. Resources are traded in units of 4. Each trade, unless conducted over land, requires a minimum of 2 convoy vessels plus 1 for every additional 4 units of resource.
Every four units of a resource you import will also cost you a civilian factory, with that productive power going to the nation you are trading with. So, exports will make your industry stronger as you pull factory power from other nations, but a lot of imports will make you weaker. But you will need to import resources to keep your war machine going.
The gray button with the crane () opens your construction menu. This is where you will assign tasks to your civilian factories - building infrastructure, new factories, defenses, and so on.
Civilian factories make all the improvements to a territory. The number factories you have available for construction will depend on the size of your nation, how many factories are being dedicated to providing consumer goods for your country (your Economy Law), and how many factories you have “traded” for strategic resources. You can increase your number of civilian factories by building more, but be careful since each province can only support a certain number of productive structures. A maximum of fifteen factories will be devoted to a construction project, and any left over will work on the next item in the queue.
There are three categories of structure you can build with civilian factories.
- Infrastructure: Each territory has an infrastructure rating that determines how easy it is to supply units in the territory and how quickly military units can move through.
- Airfields: Airfields house your military aircraft. The larger the airfield, the more planes it can effectively field.
- Anti-aircraft: Defends a territory from enemy aircraft, and especially useful to protect industrial areas
- Radar stations: Help your aircraft detect and intercept enemy air fleets.
- Military factories: Used to produce weapons, equipment and vehicles
- Civilian factories: Used to produce and improve a nation's military/industrial capacity
- Synthetic factories: Produce synthetic oil and rubber, especially useful to nations that lack either
- Naval dockyards: Where ships are built
- Rocket base: Locations from which to launch rocket attacks on nearby nations
- Nuclear plant: Produces atomic weapons
The number of shared structures that can be built is limited by the number of slots available in that State. The number of slots can be increased by researching Industry technologies.
- Naval port: Assists in oversea supply limits and ship repair speed
- Forts: Hardens the defense of units
- Coastal fort: Hardens the defense against amphibious attacks
Province buildings are built on the smallest territory size in HoI4, the province.
The more factories you dedicate to building a specific item, the more you will produce. Infantry, armor and artillery units you make will then be assigned to the appropriate military divisions, either for new units you are constructing or reinforcement and upgrades for units in the field. Airplanes you produce will be deposited into a reserve pool. Naval units will be automatically placed in a port, though you can assign one if you would rather.
Factory output is dependent on the availability of strategic resources for higher end units, and on the efficiency cap of your industry. New production lines will take time to be perfectly efficient, and if you add factories to a production line, you will lose some of that efficiency. You can raise your factory productivity and efficiency in the Industrial research tree.
Recruit and deploy
The gray button with the tank () opens your army planner menu to recruit and deploy units. This is where you decide what types of divisions you want to train. These divisions will be filled by the equipment and vehicles you build in the production menu. You can see what is required to complete a new unit by hovering over the green progress bars.
You start with a few default divisions you can build. You can spend army experience to design new division templates or edit ones that already exist.
The game starts with reinforcement and upgrades given equal weight with the creation of new units. If you would rather focus the energy of new tanks or artillery on fresh units, instead of trickling equipment to the field, you can set your reinforcement priorities on this menu as well.
The gray button with the paper and pen () opens your logistics menu. This menu gives you an overall summary of your stockpiled equipment, whatever shortages you might have, as well as a rundown of how many strategic resources you are missing from your production lines.
Controlling your army
You move your units by selecting them with the left mouse button and then clicking their destination with the right mouse button. If you draw a box around a group of units, you can give orders to all of them. You can move troops across the ocean to a friendly territory, by starting the units in a province with a naval port and then clicking on a destination port.
Your forces are more effective when they are grouped into armies under a general's command and given plans to execute.
Creating command groups/armies
You can create armies of units by selecting a group of them and then clicking on the silhouetted portrait or green plus sign that you will see at the bottom of the screen. Then, go to the selected unit profile in the upper left and click on the silhouetted portrait. This will open up your list of generals that you can assign to the army. There are two types of military leaders – generals (who can effectively command a maximum of 24 units) and field marshals (who have no limit on the number of units they can effectively command). Generals may also have attributes that give them bonuses in certain types of combat situations. If you promote a general to field marshal, they lose their attributes.
Experience and giving orders
You will gain army experience mostly through combat, but you can start a trickle of early experience by having your soldiers "exercise". To do this, select the army group and, in the unit profile in the upper left of the screen, click the exercise button in the upper right of the menu.
You can spend experience to promote generals, giving them the ability to command greater numbers of units, or to create and edit new division types in the unit production menu.
An army group can be commanded like any other group of units and simply giving a right-click move order to a destination. However, they fight better if they are given "battle plans" – a general order that is coordinated along a front, either to advance or defend.
When you select an army group, you will see a row of general orders appear at the bottom of your screen. Each of these has rollover text that explains in detail how to use this instruction. This guide will focus on the most important ones.
Naval invasion: Use this for amphibious attacks on enemy territory. (You can move into friendly territory this way, but it is more efficient to simply use port to port movement as described above.)
When you select naval invasion, you will be asked to left-click on an origin point. This is where your army will gather for the assault. Right click on the enemy province you want to invade. Note that you will need to have some naval intelligence of every sea lane you will be crossing, so you will have to have warships patrolling or controlling those sea areas.
All plans take time, and amphibious invasions take a lot of time to plan. Once the weeks (or months) of preparation are ready, the grey arrow above the army group will turn a faded green. Press that arrow to activate the plan.
Land operations: To make a battle plan for offensive land operations, you must first define your defensive front – this is the point from which your army group will begin operations. Select the defensive front button and, on the map, draw a line to indicate where your army group will start. (In many cases, this will be a national border or the current line dividing enemy armies). Then, click the offensive front button (a line with an arrow) and draw the front to which you want your armies to advance.
The army group units will begin to organize themselves along their defensive front. When they are in place and you are ready to begin, press the green arrow and the units will begin to execute the plan.
You can research doctrines and hire advisors that will reduce the time for a military plan to be prepared or add bonuses to units that are operating with a plan.
Your ships will be automatically grouped into fleets at ports as they are constructed. If you do not like the way your fleets are organized, you can drag-and-drop silhouettes of ships from one fleet to another.
Assign commanders to your fleets by clicking on the silhouetted portrait and choosing from available naval commanders. You can spend political power points to recruit new admirals for your fleets. Like general, admirals may have skills that are assets in particular battle situations or while commanding certain types of vessels.
If you select a fleet, you will see a row of different orders appear above it. These range from simple patrol missions to convoy escort duty. Choose a mission for your fleet (submarines, for example, are best used to interrupt convoys), and then right-click on up to three contiguous sea zones, i.e., sea zones that touch each other. This fleet will then carry out that mission over these areas. You can remove these orders by returning the fleet to port and assigning a new mission.
So long as you have a fleet operating in a sea zone, you are understood to have enough intelligence about that zone to both route supply overseas through that region or to order an amphibious assault across that space.
Controlling your air force
Unlike other units, airplanes that you construct are sent to a reserves hangar. You can mobilize them by clicking on an airfield, then the create new air wing button to the upper right of the resultant menu (it has a plus sign). The larger the airfield, the more planes it can efficiently use.
Like naval units, air units operate over regions and are given specific missions relevant to the type of aircraft. Fighters can do air superiority or interception, strategic bombers can target industry or infrastructure, tactical bombers can do close support of land attacks, and so on. To assign an air wing to a region and a mission, click on an air field. This will open the air information map mode.
Left click on an air wing and then right click on the region where you want it to operate. Once it is airborne, you can decide what mission it will perform. Planes have limited range depending on their type (strategic bombers have a much greater range than interceptors) and design (dependent on technology you have researched or experience you have spent to edit their abilities).
Armies in the field will require supplies to remain in fighting shape. An army out of supply can take no offensive actions at all, including simple movement, even if unopposed. Supply is determined on a territorial basis – each territory is able to support a specific number of troops. However, the effectiveness of this supply is modified by the infrastructure of a province. If a territory can support 10 units easily, but your army is in a province with very low or damaged infrastructure, a supply bottleneck will develop, so not every unit in that army will get what it needs.
Overseas supply is done through convoys and sea ports. Larger ports can funnel more supply across the ocean, though this will also require more convoy ships. For your overseas convoys to be most effective, you will need to assign some of your naval vessels to Escort duty in the regions that they will cross.
You can check the supply lines and capacities by clicking on the Supply map mode in the menu to the lower right of the main screen.
If you have researched and built nuclear reactors, you will slowly acquire atomic weapons. To deploy an atomic bomb, you must have complete air superiority over the target province. Select the province you want to attack and press the nuclear strike icon in the lower left of the province information menu. An atomic bomb will greatly weaken the infrastructure and industry of the target, and damage any units in that area.
If you build rocket sites, you can launch attack rockets at distant provinces. These will damage the infrastructure of the target region.
Winning the war
Once a country has reached its breaking point (based on its national unity level), it will sue for peace. The peace conference proceeds in stages based on the war effort expended by the victorious powers. So, if the Allies defeat Germany and the United States achieved the most in the war, it will have the first chance to make demands on the Germans. Then, the next most significant victor will make its demands.
This continues until the victors are satisfied with the peace or no nation can afford to make additional demands on the defeated powers.
Tips to getting started
As you are learning Hearts of Iron IV, remember these important steps as you formulate your plans for world domination.
- You will start the game with a few production lines of weapons already active. The most important of these will be your infantry equipment, so, until you have more military factories, put most of your energy here.
- When you are training new units, have multiple lines of infantry going at once – either in the same territory or in different ones. If you don't, you will fall behind in army size.
- Plan out your national focuses early in the game. If you are Germany, you will want to move fast along the lines that get you claims on Austria and Czechoslovakia. The USA will need to get itself out of the Great Depression. France has to watch its political stability. Have a long term goal in mind.
- Each nation has access to extra research slots if they activate specific national focuses. These are easily identified by the beaker icons on the names. The sooner you can unlock these, the better your army will be.
- When researching, try not to rush too far ahead since there are significant penalties to pursuing technology too early in the timeline. However, if you research computing in the electrical engineering track, you can reduce your total research time by a hefty margin.
- If a powerful navy is not central to your war plans, you can usually ignore this aspect of the war and research tree. However, convoys are always useful for trade and supply, so have whatever dockyards you own focus here.
- If you are not yet in the war, let your armies exercise so they can train and earn you experience. Adding an extra brigade or support battalion to an existing division design is an easy way to beef up your forces – if you have the equipment on hand to reinforce what you have.
- In wartime, it is often better to let the new equipment fall into the hands of new units instead of reinforcing and upgrading old ones. Adjust the reinforcement and upgrading of your troops with an eye to what you need now – more active units in the field now or a stronger punch in a few months time.
- Democracies should change their economic laws as soon as they can so they can in order to free up civilian factories that are dedicated to producing civilian goods.
- Don't forget to rest your armies once they have reached their objectives. A few days of inaction will help with organization, reinforcement and supply.