The Architect’s Manual: Mastering Division Stats [v1.17+]

This guide focus on understanding the systemic gears. To navigate this complexity, I have established this technical dictionary. Consider it your reference *header* for the variables we will analyze.

• Battalions and Companies: The "building blocks" of your division. Battalions occupy the main columns and consume Combat Width. Companies (left column) function as support *plugins*: they grant specific bonuses without occupying physical space on the field.
  
• AA / AAA / SPAA: Anti-Air variants. Essential for mitigating the *debuff* from enemy air superiority and shooting down attack vectors (CAS).
  
• AT / TD: Anti-tank and Tank-Destroyer. Your "firewall" against armored units. Focused on maximizing the Penetration statistic.
  
• Armor: The cut-off value. If your Armor is higher than the enemy's Piercing, you filter 50% of the damage received.
  
• CAS (Close Air Support): Support Aviation. They inject damage directly into HP and Organization during the ground combat processing.
  
• Coordination: Defines the efficiency of damage focus. High coordination ensures your attacks are concentrated on a single target at a time, "deleting" enemy units instead of just spreading damage.
  
• Hardness: The proportion of the unit composed of metal and armor. It functions as a selector: it defines how much Soft Attack (low lethality against armor) and Hard Attack you will receive.
  
• IC (Industrial Cost): Industrial Cost. The "price" metric for each unit. Divisions with high IC are powerful, but their loss can cause a financial/industrial collapse.
  
• MIO (Military Industrial Organizations): Manufacturer bonuses (e.g., Krupp, Ford). They are passive multipliers that apply improvements to the base attributes of the produced equipment.
  
• Overrun: When the attacker's speed surpasses the defender's ability to retreat, resulting in the total annihilation of the unit (process exclusion).
  
• Soft / Hard Attack: Soft Attack (efficient against "flesh"/infantry) and Hard Attack (efficient against "steel"/armor).
  
• Sub-doctrine: Secondary specialization layers. They allow you to customize the army to give specific bonuses (e.g., an organization bonus exclusive to mechanized infantry).
  
• XP (Army Experience): The configuration resource. Necessary to edit *templates*, create equipment variants, and unlock doctrines.

For a scientific analysis, we will divide the statistics into three processing vectors. Understanding how they overlap is the key to battlefield dominance:

1. Sustainability Layer (Base Statistics): Represents the "Hardware" and the "Operating System." It defines whether the unit can move, remain active (Organization), and resist wear and tear (HP/Reliability).
   
2. Output Layer (Combat Statistics): The damage processing power. It defines lethality (Attacks), the filtering of enemy attacks (Defense/Breakthrough), and physical occupation (Combat Width).
   
3. Cost and Efficiency Layer (Auxiliary Statistics): The economy of the system. It defines the implementation cost (IC), the availability of human resources (Manpower), and energy autonomy (Fuel).

I have divided the statistics into the three classic groups.

• Maximum Speed: How fast the division moves (dictated by the slowest battalion).
  
• HP (Hit Points): The division's "life" and its capacity to absorb equipment losses.
  
• Organization: The "stamina" bar that keeps the division fighting.
  
• Recovery Rate: The speed at which Organization regenerates out of combat.
  
• Reconnaissance: Increases the chance to counter enemy tactics.
  
• Suppression: Capacity to police occupied territories and reduce resistance.
  
• Weight: Determines how many convoys are needed for sea transport.
  
• Supply Use: The "load" the division places on the local logistical system.
  
• Supply Grace: How long the division fights at 100% efficiency after supply is cut off.
  
• Reliability: Reduces equipment loss due to mechanical failure and environmental attrition.
  
• Trickleback: The percentage of casualties that return to the Manpower pool.
  
• Exp. Loss: How much XP the unit loses when replacing dead soldiers with recruits.

• Soft Attack: Number of attacks against targets with low hardness (infantry).
  
• Hard Attack: Number of attacks against armored targets.
  
• Air Attack: Capacity to shoot down planes and reduce air superiority penalties.
  
• Defense: The ability to avoid damage while being attacked (when on the defensive).
  
• Breakthrough: The unit's "defense" while it is attacking.
  
• Armor: If higher than enemy Piercing, you take 50% less damage.
  
• Piercing: The ability to negate enemy armor.
  
• Initiative: Increases planning speed and reinforcement chance.
  
• Coordination: Defines how focused the damage is on a single enemy target to destroy it faster.
  
• Entrenchment: Cumulative defensive bonus for remaining stationary in a position.
  
• Combat Width: The "space" the division occupies on the battlefront.
  
• Hardness: The proportion of the division composed of armor (partial immunity to Soft Attack).

• Manpower: Total soldiers required.
  
• IC Cost (Production Cost): The total cost in "Equipment" to bring the division onto the field. Essential for calculating ROI (Return on Investment).
  
• Training Time: How long the unit takes to be mobilized.
  
• Fuel Capacity: How much fuel the division carries "in the tank."
  
• Fuel Usage: Fuel consumption per hour while moving or in combat.

Summary: How quickly can this division transition between provinces and exploit gaps in the enemy system?

Speed is a geographical movement metric. While it doesn't add "damage points" in the combat panel, it is the statistic that defines the travel distance on the map, allowing you to incircle and destroy whole divisions rapidly.

The final speed of a division is strictly dictated by the slowest battalion in your division.

• Infantry (Foot): 4.0 km/h (The basic standard).
  
• Cavalry: 6.4 km/h.
  
• Motorized/Mechanized: 12.0 km/h (Can vary based on the model).

If you place a single battalion of foot infantry in a tank division running at 12 km/h, the entire division will be capped at 4 km/h. Do not "contaminate" your fast divisions with slow units.

The nominal speed you see in the designer is for flat terrain and ideal weather. The game engine applies severe modifiers based on geography (according to Wiki data):

Unlike in the past, you no longer just research "Light Tank III." You design the tank itself.

• Engines: You can increase speed by investing in better engines in the designer, but this costs Reliability and IC (Industrial Cost).
  
• MIOs: If you use an Industrial Organization focused on mobility (like Chrysler or MAN), your tanks can gain bonuses of +5% to +15% maximum speed.

Fast battalions (tanks, trucks) depend on fuel. If the division's fuel reaches zero, the speed suffers a massive penalty, dropping to values close to 1.0 km/h. Strategically speaking: a fast division without fuel is slower than a foot soldier and becomes an easy target for encirclement.

Contrary to popular belief, support companies can affect speed, depending on the company.

Summary: How much physical punishment can the division withstand before being destroyed, and how much of its equipment will be lost in the process?

HP (or Strength) represents the physical integrity of the unit: its soldiers and its machinery. It is crucial not to confuse HP with Organization. While Organization is a volatile resource that recovers over time, HP is a material resource; losing it means soldiers have died and tanks have been turned into scrap.

HP functions as a divisor in the equipment loss equation.

• Golden Rule: The higher the division's total HP, the less equipment it loses when taking damage.
  
• Practical Example: Divisions with a lot of "cheap HP" (Infantry) manage to protect their "expensive equipment" (Artillery and Tanks). If you create a division with a lot of Artillery and little Infantry, its total HP will be very low. Result: every shot the division takes will destroy a huge amount of expensive guns because there aren't enough "bodies" to absorb the impact.

HP is a direct multiplier of all other statistics. The relationship is linear and in real-time:
If your tank division has 1000 Soft Attack, but is only at 60% HP (Strength), it will only deal 600 damage. Maintaining the flow of reinforcements (logistics) is therefore the same as keeping your division's "processing" at maximum.

HP is the raw sum of all battalions. Note the disparity:

• Mechanized Infantry: ~30 HP (The meat and metal tanks of the game).
  
• Regular Infantry: 25 HP (Excellent cost-to-benefit ratio for "tanking" damage).
  
• Medium/Heavy Tanks: 2.0 to 3.0 HP (Surprisingly low! Tanks require infantry to have sufficient HP).
  
• Artillery / Anti-Tank / AA: 0.2 to 0.6 HP (Extremely fragile).

In the current game, with increased production cost (IC) due to modular designers, HP has become an economic statistic. Low-HP divisions are "resource drains." When designing a division, you are not just looking for attack power, but for sufficient HP density so that the division doesn't financially evaporate after the first week of offense.

Tip for the Reader: Always check the yellow bar (Strength) below the green bar (Organization) on the map. If the yellow bar is low, your division is operating with damaged hardware and urgently needs time to receive new equipment from the stockpile.

Summary: How long can the division sustain combat processing before experiencing a "time-out" and retreating?

If HP is the hardware (the physical machine), Organization is the running software or the energy itself. If it reaches zero, the process is interrupted. In combat, Organization is continuously drained; when exhausted, the unit ceases attacking or abandons its defensive position.

Unlike HP, which is summed up, the division's Organization is the arithmetic mean of all battalions. This creates an optimization challenge:

• High Morale Battalions: Infantry (regular, motorized, or mechanized) have high values (~50-60). They are the division's "stabilizers."
  
• Zero Morale Battalions: Artillery, Anti-Tank, and Anti-Air have zero organization.

Critical Calculation: If you add too many Artillery battalions (Line Artillery) to increase damage, you will dilute the average Organization. A division with high attack but only 20 Organization will "melt down" and retreat before it can even apply its damage to the enemy.

• Defense: When Org hits zero, the division retreats to an adjacent friendly province.
  
• Encirclement: If the division has nowhere to retreat (due to being encircled or lacking connected infrastructure), it is deleted. In the current meta, with increased armored speed, "Overrun" (when the enemy reaches the destination before you retreat) is the most common way to lose entire divisions.

With the new doctrine system, Organization can be manipulated more granularly:

• Mobile Infantry (Sub-doctrine): Currently, for tank divisions, this sub-doctrine is essential. It provides massive Organization bonuses to the motorized/mechanized infantry accompanying the tanks, allowing your armored divisions to remain in combat for much longer.
  
• Large Unit Tactics: Some sub-doctrines now reduce infantry combat width, allowing you to fit more "meat" (and thus more Org) into the same front line.

Moving costs energy. The default loss rate is 0.20 per hour. This means if you march across the Soviet Union on foot, your troops will arrive at the front line exhausted and vulnerable.
Strategy: Use rail transport (Strategic Redeployment) for long distances, but beware: this instantly zeros out the organization upon arrival, leaving the unit vulnerable for a few hours until it reorganizes.

For attack divisions (Pushers), always aim to keep Organization above 30. For pure defense divisions (Holders), values above 50 are recommended to withstand persistent attacks.

Summary: How quickly does the division recharge its Organization after being withdrawn from combat or during tactical pauses?

Recovery Rate defines the hourly rate of Organization regeneration. Think of it as the unit's "cooldown time." In a war of attrition, the winner is the one who can regain stamina and return to the fight faster than the opponent.

Unlike in 2020, recovery is now binary: if the division is Out of Supply, the recovery rate drops drastically or stops completely.

• Logistical Data Flow: If your division is far from a Supply Hub or if the railway has been bombed, the recovery rate will suffer a penalty. Starving and out-of-ammo troops do not reorganize.

Just like Organization, the Recovery Rate is the arithmetic mean of all battalions.

• Quick Response Units: Infantry and Special Forces (Commandos, Mountaineers) have the highest rates (~0.30 to 0.45).
  
• High Latency Units: Artillery and Anti-Tank have a rate of zero.

Design Note: When creating divisions with an excess of heavy artillery, you not only lower the total Organization but also increase the time the division needs to remain stationary to recover. This makes them inefficient for rapid offensives (Blitzkrieg).

According to the latest doctrine records (Superior Firepower), recovery is one of the major focuses for defensive combat and "mass black builds":

• Superior Firepower (Main Doctrine): Currently provides a massive recovery bonus, allowing your divisions to rotate on the front line with impressive agility.
  
• Infantry Sub-doctrines: Allow specializing battalions to recover morale even in difficult terrain like mountains or swamps, where the climate would normally destroy your regeneration rate.

Remember: divisions lose Organization when moving. If your recovery rate is lower than the loss from movement (0.20/hour), your unit will arrive at its destination completely exhausted. Well-equipped motorized divisions can balance this equation, arriving ready for combat.

Technical Tip: If you are playing as a nation with low industry and few resources, focus on Recovery Doctrines (like Grand Battle Plan or Superior Firepower). This allows you to use the same divisions repeatedly, compensating for the lack of extra units with the high availability of existing ones.

Summary: The ability of your division to monitor enemy movements and anticipate their tactical maneuvers on the battlefield.

In Hearts of Iron IV, combat is not just an exchange of fire; it is a dynamic system that selects new "Combat Tactics" every 24 hours. Reconnaissance functions as a layer of Signal Intelligence (SIGINT): it provides your General with the necessary data to run a more efficient tactical selection algorithm, drastically increasing the probability of countering the opponent's strategy.
Every tactic in the game has a specific vulnerability. If your general chooses "Assault" and the enemy chooses "Ambush," the enemy's bonus can invalidate your attack. Reconnaissance enters here as a mathematical weight on the scale:

• Reconnaissance Points: These are calculated by summing the division's Recon value with the General's skill level.
  
• The Tactical Advantage: The side with more Recon points has a significantly higher chance of choosing a tactic that is the direct "counter" to the enemy's tactic.
  
• The Real Impact: A successful counter can apply massive modifiers, such as +25% damage for you or -20% damage suffered. Scientifically speaking, Recon reduces the negative variability of combat RNG (random number generator).

In 2026, the choice of the Recon support company depends entirely on your industrial setup and the operating terrain:
To verify if your investment in Recon is paying off, observe the combat bubble:

• Icon Struck Through in Red: Indicates that the enemy General has been "read" and their tactic has been nullified by yours. You are operating at maximum efficiency.
  
• General Level: Remember that Recon is a multiplier. A Level 5 General with Armored Car Recon is virtually impossible to be tactically surprised by an inferior opponent.

When designing Light Tanks for the Recon company, focus on high Reliability and low cost. The goal here is not for the tank to fight on the front line, but to provide the sensors (Recon) and a small armor increment for the infantry without breaking down mid-march.

Summary: How efficient is the division at policing occupied territories, minimizing revolts, and protecting supply lines.

Many players ignore Suppression until their factories start blowing up and their railways are sabotaged. In the current system, Suppression is no longer about moving troops into cities; it's about the maintenance cost of your order over the enemy.

Unlike in the past, you choose a template in the Occupation menu, and the game automatically calculates how many men and equipment are needed.

• Resistance: The higher it is, the more damage your troops suffer and the more factories are sabotaged.
  
• Compliance: The higher it is, the more resources and factories you gain from the territory. Good suppression allows Compliance to grow without interruption.

Suppression is a raw sum. However, the cost-benefit varies greatly depending on the equipment:


The Military Police support company is the only one that makes a real difference here. It does not add a fixed value but rather a multiplicative percentage (20% to 50% depending on technology) on the division's total suppression.
Technical Note: The larger the division (more battalions), the more effective the MP bonus becomes. This is why, for garrisons, the ideal is to create large divisions (e.g., 25 cavalry battalions with MP).

• Economic Standard: Cavalry only. It is cheap in terms of production, although it costs more manpower.
  
• Professional Standard: Armored Cars or Interwar Light Tanks. They offer the best suppression and possess "Hardness," which drastically reduces casualties suffered by your garrison from resistance attacks.
  
• The Common Mistake: Never use Artillery or Anti-Air in occupation divisions. They have zero suppression and only increase the industrial cost of your garrison.

Remember that your division's Suppression statistic works in conjunction with the chosen Occupation Law (e.g., Civilian Oversight, Martial Law). Harsher laws require more troops but reduce resistance faster. If your division has high Suppression, you can use milder laws to focus on gaining Compliance.

Tip for the Reader: If you are playing as a country with low Manpower, use Armored Cars. If you have men to spare but little industry, go with Cavalry.

Summary: How much space your division occupies in convoys during sea transport.

Although it is a statistic often ignored in purely land-based wars, Weight is the determining factor for projecting power across the sea. For those dealing with data security, Weight is like the Payload of a packet: the larger it is, the more "bandwidth" (convoys) you need, and the greater the exposure to risk during transit.

Weight dictates how many Convoys are needed to move the division from one port to another. If your convoy stock is low, you won't be able to move heavy divisions simultaneously, creating a logistical bottleneck. In the current meta, where industrial production is more expensive due to modular designs, losing heavy divisions at sea due to lack of escort is a fatal strategic error.

Divisions with high weight (packed with tanks and artillery) require more transport resources and preparation time. Furthermore, they are extremely lucrative targets for submarine interceptions; if the convoy is sunk, the heavy equipment, which has a very high industrial cost (IC), is permanently lost.

The final value is the sum of the weight of all battalions. While infantry and special forces (like Marines and Rangers) are optimized to be light and easy to transport, heavy and modern tanks increase weight drastically.

When planning naval invasions in 2026, try to balance firepower with weight. An overly heavy division might get "stuck" in the port due to a lack of transport capacity, invalidating your element of surprise strategy.

Summary: How many logistical resources (ammunition, rations, reserve fuel) your division consumes to operate without suffering performance degradation.

Unlike weapons or tanks, you do not "manufacture" supplies in military factories. They are automatically generated by your capital and transmitted through the railway network. Supply is the Bandwidth of your battlefront: if the consumption by divisions (traffic) exceeds the capacity of the local Hub, the system suffers throttling and performance drops drastically.
Supply travels from your Capital to the Supply Hubs via railways. From the Hub, it is delivered to the divisions by trucks or horses.

• Bottlenecks: If the railway is low-level or bombed, the Hub will not receive the full "package," and your divisions will starve even if you have surplus resources in the capital.
  
• Range: The farther the division is from the Hub, the lower the delivery efficiency. You can increase this range by motorizing the Hub (using trucks), but this increases your global fuel consumption.

Every province has a load limit. If you place too many divisions in a swamp or mountain, the sum of their Supply Use will cause a "buffer overflow." The penalties are severe:

• Stat Degradation: Massive loss in Attack and Defense (up to -90%).
  
• Organization: Recovery rate slows down or stops completely.
  
• Logistical Attrition: Your troops begin losing equipment on their own (breakdowns due to lack of maintenance and abandonment).

Supply use is the raw sum of all battalions.

• Heavy Consumers: Tanks, Artillery, and Mechanized Battalions demand heavy logistics.
  
• Light Consumers: Infantry and Special Forces (like Mountaineers and Rangers) are optimized to fight where logistics are scarce.
  
• Logistics Company: Essential in 2026. It reduces the division's total consumption by a fixed percentage. In large divisions, the logistical "space" it saves allows for the addition of more firepower without exceeding the Hub's limit.

A new and vital statistic. It is the time your division can endure fighting after the total logistical connection is cut (e.g., an encirclement). Doctrines like Mass Assault increase this time, allowing your divisions to operate in "offline mode" for longer before total collapse.
Treat Supply Use like the maintenance cost of a server. Before adding that extra heavy artillery battalion, check if the region's infrastructure (railway) can support the increased traffic. In modern HOI4, logistics win wars more than cannons do.

Summary The resistance of your equipment against mechanical failures, accidents, and natural wear caused by the environment.

Reliability is the statistic that separates a modern, functional army from an expensive pile of scrap. While the enemy tries to destroy your divisions with bullets and bombs, the environment and mechanics try to destroy them through Attrition. Having high reliability ensures that your country spends factories producing new armies, instead of just replacing tanks that broke down on their own during transit.

If you neglect this statistic in countries with immense front lines or extreme climates (like Siberia or the Amazon), you will face industrial collapse. Ignored attrition drains your Stockpile. When the stockpile hits zero, your divisions fight with reduced "Strength," which drags down all your other attributes (attack, defense, and organization), leading to an inevitable defeat due to material exhaustion.
Attrition is a constant force that "pulls" your equipment into the trash. It is activated by four main factors:

• Terrain and Climate Mountains, swamps, deserts, deep snow, and mud are the biggest villains. They increase the chance of accidents and failures.
  
• Movement Troops in constant march suffer more wear than stationary troops.
  
• Training Units training to gain experience continuously lose equipment.
  
• Combat Beyond direct losses from gunfire, combat generates immense mechanical stress.

Reliability acts as the mathematical "shield" against this Attrition. If your reliability is low (e.g., 40%), almost every point of attrition will result in a real equipment loss. If it is high (80% to 100%), the vast majority of these "accidents" will be avoided, preserving your stockpile.

In modern Hearts of Iron IV, the golden rule for tanks and planes is to seek balance. Extremely powerful equipment with 30% reliability is a trap: you will have a "glass cannon" that shatters on its own.

• Safety Limit For Medium and Heavy Tanks, try never to drop below 80%.
  
• Infantry Weapons and support equipment usually have default reliability between 80% and 90%, which makes them easy to maintain.
  
• The Cost of Power In the Tank Designer, every improved armor or cannon module reduces reliability. Use the chassis and engine to compensate for this loss.

To avoid logistical disasters (like losing tens of thousands of rifles in a few months), use the following tools:
When designing tanks, remember: it is better to have a tank that is 10% less powerful but reaches the battle than a "perfect" tank abandoned in a ditch 200km from the front line. In the 2026 meta, reliability is what sustains long-duration offensives.

Summary: The percentage of wounded soldiers in combat who are saved and return to the country's Manpower pool.

Trickleback is a human preservation statistic. In war, casualties are inevitable, but not every soldier hit needs to be a permanent loss. In Hearts of Iron IV, the baseline trickleback for any division is 0%, meaning every casualty is permanently subtracted from your military population. By increasing this statistic, you create a human resource recycling system.
The primary way to gain Trickleback is by adding the Field Hospital support company.

• The Calculation: If a division has 20% Trickleback and loses 1,000 men in a battle, 200 of those soldiers do not die; they are treated and sent back to your available Manpower pool.
  
• Fate of the Men: These returning soldiers can be used to reinforce the same division, fill new divisions, or even be conscripted into the Air Force or Navy.

Trickleback efficiency increases as you research more advanced medical technologies in the support tab:
The Field Hospital consumes Trucks and Support Equipment. Before adding it to all your divisions, verify if your industry can produce enough trucks to keep the ambulances running. In garrison or secondary defense divisions, the cost of the hospital might not be worth it, but in elite divisions constantly under fire, it is an essential investment for campaign sustainability.

Summary: How much experience the division manages to preserve when replacing fallen soldiers with new recruits from the reserve.

Division experience is one of its greatest strategic assets. A "Veteran" unit has massive attack and defense bonuses compared to a "Recruit" unit. However, war consumes lives. When an experienced soldier dies, they are replaced by an untrained recruit, which "dilutes" the average experience and effectiveness of the division on the battlefield.
Division experience works as a simple arithmetic average of the competence of all soldiers present within it.

• The Problem: When your division suffers casualties (loss of HP/Strength), the game must fill those slots with men from your Manpower pool. Since these new soldiers arrive with zero experience, the overall level of the division drops.
  
• Combat Consequence: Losing Veterancy means losing direct modifiers. A unit dropping from "Veteran" to "Trained" loses significant combat bonuses, making it more vulnerable and less lethal.

The only technical way to mitigate this performance drop is through the Field Hospital support company. This company not only saves lives (Trickleback) but also reduces the penalty applied to experience when reinforcements arrive.
Unlike Trickleback (which focuses on manpower economy), the reduction of Experience Lost focuses on quality maintenance. If you are playing as a country with few resources but requiring extremely high-quality units (like Germany or Japan), investing in hospitals to reduce this loss is the key to maintaining tactical superiority against numerically superior enemies.

Summary: How many attacks are carried out per hour against the "light" or unarmored parts (like infantry) of an enemy division.

Soft Attack continues to be the "king" of offensive statistics. Since the vast majority of units in Hearts of Iron IV—especially those used by the AI—are composed of infantry with low armor, Soft Attack is primarily responsible for melting enemy organization and winning battles.
The effectiveness of your Soft Attack is entirely dictated by the Hardness of the target you are attacking.

• "Flesh" Targets: Units like infantry, cavalry, and motorized artillery have 0% or very low hardness. They receive 100% of your light damage.
  
• "Steel" Targets: Heavy and modern tanks can have 80% to 100% hardness. Against them, your Soft Attack is practically useless, being ignored in favor of Hard Attack.
  
• Optimization: Since most divisions in the game are composed mainly of infantry, having high Soft Attack ensures you can push enemy lines in the majority of situations.

Soft Attack causes more than just casualties; it causes chaos. The damage is distributed probabilistically between the physical life and the morale of the troops:

• Damage to Organization (2/3): The largest impact goes to morale, forcing the enemy to retreat from the province.
  
• Damage to HP (1/3): The remainder of the damage destroys equipment and permanently removes manpower.

When designing your offensive divisions, the focus should be on balancing Soft Attack with Combat Width. High attack is useless if the division is so large that it doesn't fit into the battle terrain. Furthermore, remember: Soft Attack wins the battle against infantry, but Hard Attack is what prevents enemy tanks from destroying you.

Summary: How many attacks are carried out per hour against the "hard" or armored parts (like tanks and mechanized vehicles) of an enemy division.

Hard Attack is the specialist in destroying steel. While Soft Attack focuses on eliminating infantry, Hard Attack is designed to pierce armor and disable vehicles that conventional weapons (rifles and standard grenades) cannot even scratch. On the battlefield, it is your insurance against enemy tank divisions.

The utility of this statistic depends entirely on how "hard" your target is. The game divides incoming damage proportionally:

• Divisions with 0% Hardness (Infantry): They ignore almost all of your Hard Attack. Attacking foot soldiers with high-velocity anti-tank guns is a waste of resources.
  
• Divisions with 100% Hardness (Modern Tanks): They ignore almost all of your Soft Attack. Here, only Hard Attack will cause real damage.
  
• Mixed Divisions: If an enemy has 50% hardness, they will receive half of your Soft Attack and half of your Hard Attack.

Hard Attack is heavily tied to the technology of high-caliber guns and special ammunition:

• Anti-Tank (AT) Artillery: This is the cheapest way to give "teeth" to your infantry. Placing an anti-tank support company helps repel light armor, but might not be sufficient against heavy tanks.
  
• Tank Destroyers (TDs): These are tank chassis equipped with very high-caliber guns. In the current meta (v1.17+), TDs have received upgrades and are the units with the highest Hard Attack per combat width.
  
• Infantry Anti-Tank Weapons: Researching technologies like Bazookas and Panzerschrecks adds a passive Hard Attack value to your regular infantry.

With recent updates, Hard Attack has become more versatile through Artillery and Armor Sub-doctrines:

• TD Specialization: It is now possible to select sub-doctrines that specifically increase the damage of anti-tank units, allowing smaller nations to destroy major power tanks with focused investments.
  
• Tank Designer: In the modular designer, Hard Attack is defined by the gun type. "High Velocity" guns are the kings of Hard Attack, but they usually have very low Soft Attack.

Do not over-invest in Hard Attack if your enemy does not use tanks (such as when fighting China or in mountain terrain). Hard Attack has a high production cost (IC), and if the target is infantry, that investment will be wasted. The secret is to have just enough to "punch through" enemy armor, but keep the focus on Soft Attack to win the war of attrition.

Summary: The ability of your division to shoot down enemy aircraft and reduce the penalties caused by the opponent's air superiority.

Air Attack is your shield against the sky. In past versions, many players ignored this statistic, but in the current meta (v1.17+), it has become almost mandatory. If the enemy controls the air and you have no Air Attack, your divisions will be massacred by bombers before they can even retaliate on the ground.

Unlike other statistics, Air Attack works on two simultaneous fronts to protect your troops:

• Shooting Down Planes (Direct Damage): During ground combat, if the enemy sends Close Air Support (CAS) planes, your division will use its Air Attack to shoot them down. This destroys the enemy's industrial capacity over time.
  
• Penalty Reduction: Being under enemy air superiority causes heavy penalties to your Defense and Breakthrough. Having AA in the division drastically reduces these negative effects, allowing your soldiers to fight at an efficiency much closer to normal.

No division possesses inherent Air Attack; you must add specific equipment to obtain this protection:

• Anti-Aircraft Support Company: This is the most popular and cost-efficient option. It does not occupy "Combat Width" and provides enough Air Attack to protect the majority of infantry divisions.
  
• Anti-Aircraft Artillery (AAA): These are line battalions. They offer more attack than support units but occupy space on the battlefront. They are ideal for countries expecting massive air fleets.
  
• Self-Propelled Anti-Aircraft (SPAA): These are tanks equipped with AA guns, designed in the Tank Designer. They offer the highest Air Attack value in the game and possess armor, making them essential for protecting your tank divisions without sacrificing speed.

In recent updates, Close Air Support (CAS) has become extremely lethal. A division without AA can lose hundreds of men and tanks in just a few days of combat solely due to air attacks.


Divisional Air Attack also helps pierce light armor. If you are facing armored cars or interwar tanks and lack anti-tank (AT) guns, your AA might end up serving as an improvised emergency solution, as it possesses a moderate Piercing value.

Summary The ability of your division to nullify enemy attacks while protecting a position. It is the statistic that defines how well you can "hold the line" without suffering massive damage.

Defense functions as a stock of "blocks" that your unit uses against every incoming attack. In Hearts of Iron IV, being on the defensive is mathematically much more efficient than attacking, which makes this statistic the foundation of any survival strategy.

Defense is the sum of all battalions. Historically and mechanically, infantry is the queen of defense:

• Regular Infantry: Offers the best defense for the lowest industrial cost (IC). It is the base of any defensive army.
  
• Mechanized Infantry: Is the pinnacle of ground defense. It possesses very high defense values combined with "Hardness," making it almost impossible to remove from a fortified position.
  
• Armor (Tanks): Tanks have low defenses. They are made for attacking (see the Breakthrough section). Never use tanks alone to hold a line; they must always be accompanied by infantry to provide the necessary defense.

To understand Defense, you need to understand how hits are calculated. Think of Defense as a pool of shield points that renew every hour of combat:

• With Remaining Defense: As long as your division's Defense value is greater than the enemy's Attack, the chance of you being hit is only 10% (you avoid 90% of attacks).
  
• Without Defense (Defense Depleted): If the enemy has more attack than you have defense, the attacks that "spill over" will hit your troops much more easily. The chance of taking damage rises to 40% (you only avoid 60%).

Conclusion: Having high defense ensures that the enemy almost never manages to overcome your "blocks," causing your division to suffer very few casualties and maintain high Organization for much longer.

Besides line battalions, there are other vital ways to increase your defensive capability:

• Engineers Company: Essential. They increase defense and Entrenchment, which is a multiplicative bonus applied to base defense.
  
• Doctrines and Sub-doctrines: In the current meta (2026), the Superior Firepower doctrine is excellent for defensive builds. Meanwhile, Grand Battle Plan focuses on maximizing the entrenchment and defensive coordination bonus.
  
• Terrain and Fortifications: Defending mountains, rivers, or forts drastically increases the effectiveness of your defense statistic.

A critical detail in the modern game is that if the enemy has total control of the skies (Air Superiority), your Defense statistic suffers a heavy penalty. This means that even with a perfect infantry division, you can be defeated if you lack Air Attack or fighters to protect your troops.


Defense is cheap. While an attack division (tanks) costs thousands of production points, a solid defense division (infantry) costs a fraction of that. For smaller nations, the secret to victory is investing in a defense that inflicts so much attrition on the enemy that they exhaust their manpower and equipment before they can break through your lines.

Summary: The ability of your division to avoid enemy attacks while attacking a position. It is essentially the attacker's "Defense."

Many beginner players try to attack using only infantry and do not understand why their divisions lose so much organization and men so quickly. The answer is almost always the lack of Breakthrough. While Defense protects those who are stationary, Breakthrough protects those advancing under enemy fire. If your unit is moving into enemy territory, it uses its Breakthrough value; if it is stationary receiving an attack, it uses its Defense value.

Breakthrough functions under the exact same mathematical logic as Defense (see the Defense section for details on how hits are calculated):

• While Breakthrough Remains: Every point of Breakthrough cancels one enemy attack. As long as you have Breakthrough "shields," the chance of the enemy hitting you is only 10%.
  
• When Breakthrough is Exhausted: If the defender's Attack is greater than your Breakthrough, the surplus attacks will hit your troops much more easily, raising the chance of taking damage to 40%.

This explains why tanks can advance for kilometers taking few casualties, while infantry "melts" trying to cross an open field against machine guns: tanks have Breakthrough to ignore defensive fire, infantry has almost none.

Unlike Defense, which is cheap and abundant in infantry, Breakthrough is an expensive statistic concentrated in mobile and armored units:

• Tanks (Light, Medium, and Heavy): They are the primary sources of this statistic. In the Tank Designer, the choice of chassis and radio is crucial for maximizing this value.
  
• Infantry and Artillery: They have extremely low Breakthrough values. Using them to attack fortified positions without armored support is, mathematically, a waste of resources and manpower, as they will suffer 4x more damage than necessary.
  
• Tank Variants: Tank Destroyers (TD) and Self-Propelled Artillery (SPG) generally have less Breakthrough than the standard tank, as they are designed for fire support, not leading the initial charge.

In the current game system (v1.17+), Breakthrough must be analyzed alongside Coordination.

• Breakthrough Protects: It ensures your tank division stays alive and maintains high morale (Organization) during the attack.
  
• Coordination Focuses: It ensures your tank division's attack is directed at a single target at a time.

If you have high Breakthrough but low Coordination, you won't die, but the battle will last for weeks because your damage is spread out. If you have both, you will cause a "tactical breakthrough," destroying the enemy line quickly and enabling encirclements.

Always check if your Breakthrough is greater than the enemy defender's total Attack (Soft and Hard combined). If it is lower, your elite divisions will suffer disproportionate damage relative to their cost. In difficult terrain like mountains, forests, or swamps, Breakthrough suffers severe penalties of up to -50%; in these cases, even the best tanks can be stalled by well-entrenched infantry.

Summary The level of physical protection of your division that determines whether enemy shots will be deflected or cause fatal damage.

Armor is the "shield" of your elite divisions. It functions in a direct test against the opponent's Piercing statistic. In Hearts of Iron IV, having enough armor to not be pierced is one of the most powerful force multipliers in the game, turning balanced battles into one-sided massacres.

If your division's Armor is greater than the enemy's Piercing, you receive critical bonuses:

• Damage Reduction: Your division takes 50% less damage to its Organization and 50% less damage to its HP (Strength).
  
• Damage to HP: The chance for a division to take damage directly to its HP (equipment destruction and deaths) instead of just Organization drops drastically to about 1/6 (16.6%).
  
• Combat Impact: In practice, an unpierced tank division can fight for much longer and suffer half the material wear and tear compared to a division that was pierced.

If the enemy has a Piercing value close to your armor (even if lower), they will cause proportional damage. However, the 50% damage reduction bonus is only fully maintained if your armor is superior to the opponent's total piercing.

Armor is not a simple average. To prevent the system from being unfair, the game uses a weighted average that favors the strongest battalion:

• Calculation: 40% of the highest Armor in the division + 60% of the average Armor of all battalions.
  
• Practical Application: This means adding a single Heavy Tank or Super-Heavy Tank battalion to an infantry or light tank division will significantly increase the division's total armor, even if the other battalions are vulnerable.

With the modular designer system, Armor is no longer a fixed value per model but a design choice:

• Armor Types: You can choose between riveted armor (cheap), welded (balanced), or cast (maximum protection, but high industrial cost).
  
• Armor Points: You can invest points to increase plate thickness. However, every added armor point reduces the vehicle's Maximum Speed and Reliability.
  
• MIOs (Industrial Organizations): Manufacturers focused on heavy armor (like Henschel or Porsche) provide percentage bonuses that raise this value without extra production cost.

Always adjust your tank armor based on what your enemy can produce. If enemy infantry only uses basic anti-tank support, you do not need excessively expensive armor; just enough to overcome their piercing guarantees the 50% bonus. Saving on the Industrial Cost (IC) of armor allows you to field more tanks in battle.

Summary: The capability of your weapons to pierce enemy armor and nullify the defensive advantages of opponent tanks.

Piercing is the direct counter-attack to Armor. If the enemy brings a "shield" (tank), you need a "spear" (piercing) capable of penetrating it. In modern Hearts of Iron IV, it's not enough just to have attack; if you cannot pierce the enemy, your shots will simply ricochet, dealing only half the intended damage.

The gamemeta a Partial Piercing system. This means that even if you cannot fully pierce enemy armor, having a high value still helps:

• Full Piercing (Piercing > Armor): You deal 100% damage and negate all of the enemy tank's defensive bonuses.
  
• Partial Piercing: If your piercing is greater than half of the enemy armor, you already start dealing more damage than if you had no piercing at all.
  
• No Piercing (Piercing < 50% of Armor): Your attacks are ineffective. The enemy will receive only half damage, and your division will suffer heavy casualties quickly.

Just like armor, piercing follows a weighted logic to ensure specialized anti-tank weapons make a difference:

• Calculation: 40% of the highest Piercing in the division + 60% of the average Piercing of all battalions and companies.
  
• Differential: Note that support companies (like Anti-Tank) enter the average calculation, making technological upgrades to these pieces essential for keeping the division relevant against modern armor.

This means you don't need every soldier to have heavy anti-tank weapons. Adding just one Anti-Tank Support Company or one Tank Destroyer (TD) battalion drastically raises the capacity of the entire division to deal with armor.

• Infantry Technology: Researching "Infantry Anti-Tank Weapons" (like Bazookas and Panzerschrecks) gives a passive piercing bonus to all your regular infantry battalions.
  
• Anti-Tank Artillery (AT): The most efficient form for defensive divisions. 1940 and 1942 guns can handle most medium tanks.
  
• Tank Destroyers (TDs): In the modular tank designer, equipping a chassis with a "High Velocity" gun creates the definitive piercing weapon.
  
• Sub-doctrines (Novelty): You can now select artillery sub-doctrines that specifically increase the piercing of your anti-tank battalions, making them lethal against elite divisions.

Always check the Armor value your main enemies are using. Do not waste expensive resources producing heavy Tank Destroyers if the enemy only uses Light Tanks or Cavalry; in those cases, a simple low-cost Anti-Tank support company is more than enough to ensure you deal full damage.

Summary: The efficiency of the division's internal communication, determining how quickly it plans an attack and how fast it joins combat from the reserve.

Initiative is a "response time" statistic. In modern Hearts of Iron IV, it is the main engine behind Reinforce Rate and Coordination. For an army to function like a well-oiled machine, orders need to arrive fast, and that is what Initiative simulates.

When you draw an offensive line with a general, your divisions start accumulating a "Planning" bonus that drastically increases their attack.

Divisions with high Initiative fill this bonus bar much faster. This is vital for Blitzkrieg strategies, where you don't want to wait weeks standing still for your tanks to be ready for the next leap.

The Battle of Reserves (Reinforce Rate) is the most critical defensive aspect of Initiative. In combat, the space on the front line is limited (see the Combat Width section). If you have 10 divisions in a province, maybe only 3 can fight at the same time; the other 7 stay in "Reserve".

If the 3 frontline divisions run out of organization and retreat, and the reserve divisions don't "notice" in time to enter the fight, the enemy will win the battle and take the province immediately — even if you had thousands of fresh soldiers in reserve.

Initiative increases the hourly chance of a division leaving the reserve and entering active combat. This prevents the so-called "Reinforce Meme," which is when you lose a province despite having plenty of troops on location.

In the most recent updates (v1.17+), Initiative gained a devastating offensive function through the Signal Company. Now, this company is the main source of Coordination.

High Coordination causes your divisions to focus all their attack on a single enemy division at a time, instead of spreading the damage. This allows you to "delete" enemy units from the front line one by one with surgical efficiency.


I recommend using signal companies in two specific scenarios:

1. Breakthrough Divisions (Tanks): To ensure the planning bonus rises quickly and damage is coordinated to break the enemy line in hours, not days.
   
2. Congested Battlefronts: If you are defending an area with many divisions (like the Rhine or the Stalin Line), initiative ensures your reserves enter the fight as soon as the frontline units tire, creating an infinite defensive wall.

Summary How well a division can prepare defensively while stationary, creating improvised fortifications to gain massive combat bonuses.

Entrenchment represents the time your soldiers spend digging trenches, setting up machine gun nests, and mapping the surrounding terrain. In Hearts of Iron IV, a unit that has had time to prepare is orders of magnitude harder to defeat than a unit that has just arrived at the front line.

Every point of Entrenchment provides a direct bonus of +2% Attack and Defense (in most standard configurations). If a division has an entrenchment limit of 20, it will fight with a 40% bonus to its defensive statistics.

• The Time Factor: Entrenchment is not instantaneous. It grows daily as long as the division remains stationary and unattacked.
  
• Bonus Fragility: Entrenchment is lost immediately if the division moves (even to an adjacent province) or is forced to retreat. It rewards the player who knows where to position their troops in advance.

Entrenchment shines when combined with the right terrain. A well-prepared division in a mountain, behind a river, or in a dense forest can hold back the advance of entire armies. The entrenchment bonus is applied on top of the natural terrain bonuses, creating an "invisible fortress" that drains the attacker's organization and strength.

To increase the limit of how well your soldiers can prepare, there are specific tools in the game:


If you are playing as a small country fighting a major power, your best chance is "Defense in Depth." Position your troops in defensible terrain and let the entrenchment timer rise to its maximum. Often, the AI or other players will give up attacking a position with a 50% or 60% entrenchment bonus because the cost in men and tanks would be prohibitive.

Summary: The "physical size" of your division, which determines how many units can fight simultaneously in a given portion of terrain.

Space on the battlefield is not infinite. Imagine a narrow road: it doesn't matter if you have a thousand cars; only two or three can pass side-by-side at a time. In Hearts of Iron IV, Combat Width functions exactly like this. If you stack too many divisions in a single battle, the "excess" will remain in reserve, waiting for space to fight.

Each terrain type has a basic "width" capacity. Unlike older versions of the game (where almost everything was 80), the most recent updates (2024/2025) have made terrains more varied to prevent a single perfect size from existing for everything.

• Plains and Deserts: These are open areas with great width, allowing many divisions to fight at the same time.
  
• Mountains and Swamps: These are natural "choke points." The combat width here is very small, allowing a single small, well-trained division to hold an entire army.
  
• Multi-directional Attacks: Whenever you attack a province from more than one side (flanking), the combat width of that battle increases. This is crucial for breaking strong defenses, as it opens space for more of your divisions to enter active combat.

Every battalion you add in the Division Designer increases the unit's total width. Standard values are:

The game never splits a unit. If the battle has a remaining space of 10 and your next division in reserve has a width of 20, it will not enter the fight. It will wait until a fighting division retreats or is destroyed, opening the required 20 points of space. Therefore, having divisions with widths that "fit" the terrain numbers is the key to efficiency.

If you force too many divisions into a small space (exceeding the province limit), the game will apply a severe combat penalty to all involved divisions. This is the "trampling" effect: too many soldiers bumping into each other, preventing anyone from shooting straight. The AI system generally avoids this by automatically placing the excess in reserve.

Note: The Mass Assault Doctrine has a technology that reduces infantry width to 1.6, allowing nearly 25% more soldiers to fit into the same combat space.

In the 2026 meta, widths between 15 and 35 tend to be the most versatile. Divisions with a width of 15 or 21 are excellent for defending rugged terrain (Mountains/Forests), while divisions with a width of 30 or 35 are ideal for tank offensives on plains. Always check the combat bubble to see if your divisions are actually fighting or just "watching" from reserve due to lack of space.

Summary The proportion of your division composed of armored vehicles, determining how incoming damage is filtered between Soft Attack and Hard Attack.

Hardness is one of the most powerful survival statistics for elite units. It functions as a selector that defines which types of enemy attacks can effectively hit your division. In practice, the higher the hardness, the less your unit cares about rifles and machine guns (Soft Attack) and the more it must worry about anti-tank guns and armor-piercing weapons (Hard Attack).

The main advantage of focusing on Hardness is forcing the enemy into an industrial dilemma. To defeat a division with 90% hardness, the opponent is forced to produce large quantities of expensive Anti-Tank Artillery or Tank Destroyers. If they fail to do so, their infantry divisions—no matter how numerous—will cause insignificant damage because most of their firepower (Soft Attack) will simply be discarded by the unit's hardness filter.

The mathematics of Hardness are direct and affect the calculation of the attacker's firepower. If a division has 70% Hardness, the calculation of received damage follows this logic:

• Heavy Component (70%): The division will receive 70% of the enemy's Hard Attack.
  
• Light Component (30%): The division will receive 30% of the enemy's Soft Attack.

Since most divisions in the game (especially infantry) have very high Soft Attack and very low Hard Attack, a division with high hardness becomes virtually immune to damage from regular infantry. This is why tanks can advance against thousands of foot soldiers while suffering minimal damage.

Hardness is the weighted average of all battalions. Every unit contributes to "hardening" or "softening" the template:

• "Soft" Units (0% Hardness): Foot Infantry, Cavalry, and towed Artillery. These units are composed of exposed soldiers and receive 100% of the enemy's soft attack.
  
• Mixed Units (40% - 60% Hardness): Mechanized Infantry and Armored Cars. They offer balanced protection, significantly reducing the impact of light weapons.
  
• "Hard" Units (80% - 99% Hardness): Medium, Heavy, and Super-Heavy Tanks. They are the pinnacle of protection. It is mathematically impossible (under normal design conditions) to reach 100% hardness, ensuring there is always a minimal fraction of vulnerability.

When assembling your divisions, be careful not to "soften" your tanks too much by adding too many motorized infantry battalions to gain organization. Try to keep the hardness at a level where the enemy's average Soft Attack is reduced to irrelevant values. If hardness drops below 50%, the unit starts taking significant damage from standard artillery, losing its role as the offensive "steel fist."

Summary: The total number of soldiers required for a division to operate at 100% of its physical capacity and combat effectiveness.

Manpower is the most fundamental and often the most scarce resource in the game. It represents the "HP" (life points) of your division. Without men to operate the rifles or drive the tanks, the division loses its ability to exert force on the map, regardless of how advanced its armament technology is.

Each unit type requires a specific amount of personnel, based on the complexity and function of the battalion. Intuitively, units that rely on large masses of foot soldiers consume more men than highly mechanized units.


The amount of available manpower is not infinite and depends directly on your country's demographics and the political decisions made by the government:

• Conscription Laws: This is the main way to increase your soldier pool. Laws such as "Limited Conscription" or "Total Mobilization" increase the percentage of the population that can be drafted, but they bring increasing penalties to industry and training time.
  
• National Spirits and Doctrines: Some nations have historical population bonuses, while the Mass Assault Doctrine offers significant bonuses to the quantity of available recruits.
  
• Medical Technologies: As seen in the Trickleback section, field hospital technologies help preserve manpower by returning wounded men to the available pool instead of losing them permanently.

In the division panel, you will see a bar called "Strength." It is the result of the combination of Manpower and Equipment. If your division requires 10,000 men and only has 5,000, it will only have 50% of its Strength.

• Combat Penalty: A division with low strength has all its other statistics (Attack, Defense, Breakthrough) reduced proportionally. A division without men cannot hold a line, even if it has the best tanks in the world.
  
• Reinforcement Priority: In the army menu, you can set which divisions receive men first. It is advisable to prioritize elite units (tanks) over garrisons.

When your country's available Manpower pool hits zero, your divisions stop receiving reinforcements. Every lost battle and every attrition event will permanently reduce the strength of your units until they are completely deleted from the map due to personnel shortage. For sparsely populated countries, this is the war's "biological limit": once reached, defeat is inevitable, as there is no way to replace losses.

Avoid changing your conscription laws to extreme levels prematurely. The jump from "Military Service Act" to "Total Mobilization" imposes severe penalties on construction speed and factory production. Try to maximize your manpower first through technology, national focus, or by focusing on troop preservation using high armor and hospitals.

Summary: The time required for recruited civilians to learn basic combat functions and operate their equipment with minimum efficiency before being sent to the front.

No one is born knowing how to operate a field radio, aim an anti-tank gun, or coordinate a mechanized advance. Training Time simulates the process of turning an ordinary citizen into a functional soldier. As a general rule, the more technical the role and the more complex the equipment, the longer the division needs to spend in the instruction center.

The base training time is directly influenced by the division composition in the Division Designer:

• Pure Infantry: This is the fastest to train (usually between 90 to 120 days). The equipment is simple, and tactics are fundamental.
  
• Elite Units: Mountaineers, Paratroopers, and Marines require much superior physical and technical conditioning, which significantly extends the training timer.
  
• Armored and Mechanized Divisions: The need to learn maintenance and operation of heavy vehicles means these units take much longer to be ready compared to foot infantry.

You have the option to "force" the deployment of a unit before training reaches 100%. However, this comes with a heavy tactical cost:

• Recruit Level (Green): Units sent too early to the battlefield receive a penalty of -25% in Attack and Defense. They are disorganized and prone to unnecessary casualties.
  
• Trained Level: This is the standard objective. A unit that completes 100% of its training starts without penalties, ready to exert its full potential.

After deployment, divisions can continue exercising on the map. This allows units that started out "green" to reach the "Regular" level, and trained units to reach the (+25% bonus) level.
Note: Training in the field consumes supplies and causes Attrition, meaning you will lose equipment due to breakdowns and accidents during exercises.

Besides equipment, external factors can accelerate or delay the formation of your armies:

• Conscription Laws: More extreme laws, such as "Compulsory Military Service," increase the time required to train each man due to system overload.
  
• Military Spirits and Advisors: Some army chiefs or national spirits focused on "Military Academy" drastically reduce training time and cause troops to start with more initial experience.

Only use early deployment (forcing the troops out) in cases of real emergency, such as an imminent enemy invasion or to hold a line that is about to collapse. In normal situations, the bonus of having a properly trained troop outweighs the waiting time. Remember: putting more men on the map without adequate training only generates more supply consumption for units that die easily.

Summary: The maximum stock of fuel the division carries in its own reservoirs to operate autonomously before depending on direct resupply.

Not every unit in Hearts of Iron IV consumes fuel; this statistic is exclusive to divisions utilizing motorized, mechanized, or armored vehicles. Fuel Capacity functions like your division's "reserve tank": it determines how many hours or days the unit can continue moving and fighting if the logistical connection to the capital is cut off.

Fuel capacity defines the division's autonomy in the field. Divisions with heavy tanks and many trucks consume fuel at an accelerated rate.

Your divisions primarily consume fuel when they are moving or in active combat. If they are stationary and well-supplied, they automatically replenish their internal stocks.

High fuel capacity is vital for breakthrough divisions that perform encirclements. If your tank division runs out of fuel while behind enemy lines, it will lose mobility and be easily destroyed.

Running out of fuel turns your elite divisions into static, vulnerable targets. The penalties for a division with 0% fuel are catastrophic:

• Speed (-90%): Your tanks and trucks will move at the speed of foot soldiers or even slower, making any rapid advance maneuver impossible.
  
• Combat Statistics: Armor and Breakthrough suffer massive penalties (up to -50%). Without fuel, the engine won't turn, and the aiming system won't function properly.
  
• Vulnerability: An unpowered armored vehicle is just an immobile metal box. The enemy will be able to pierce its armor much more easily, and its organization will drop rapidly.

Fuel capacity is useless if your country does not produce or import oil. Fuel is sent from your national stockpile to the Supply Hubs and, from there, to the divisions.

Avoid taking large motorized armies to areas with precarious infrastructure (like the interior of Africa, the Amazon, or Siberia). Fuel will rarely reach the troops, and your tanks will be abandoned due to lack of energy supply.

If your country lacks oil refineries or wells, do not invest in an army focused on tanks and trucks. It is preferable to have solid, functional infantry than an elite armored division that will spend 90% of the time stationary and without combat bonuses due to energy shortage. Always check the fuel barrel icon in the division interface before starting a major offensive.

Summary: A binary statistic (Yes/No) that defines whether the division is capable of being airlifted and airdropped behind enemy lines.

Air delivery capability enables vertical warfare. In Hearts of Iron IV, paratroopers are the ultimate tool for logistical disruption, capable of capturing victory points, encircling armies, and seizing undefended Supply Hubs. However, the game engine is extremely strict regarding the composition of these units: a single design flaw, and the division will be grounded.

For the parachute icon to appear as "Yes" in your designer, the division must adhere to a hierarchy of equipment:

• Line Battalions (Combat): All battalions in the main columns must be Paratrooper units. If you add a single Regular Infantry, Line Artillery, or Tank battalion, the division instantly loses its drop capability.
  
• Support Exception: Support companies (left column) are treated as "air-transportable." You can add Support Artillery, Anti-Tank, Engineers, and even Signals without losing the drop capability.
  
• Logistical "Weight": Every added battalion or company increases the division's Weight. The heavier the division, the more transport planes will be needed to drop a single unit.

Having the drop capability is only half the equation. You need a transport fleet capable of sustaining the weight of the operation:

• Transport Efficiency: Each transport plane has a fixed payload capacity. If your division is too heavy (packed with support companies), you will need hundreds of planes to move just a few divisions.
  
• Air Superiority: The drop is only authorized if you have air superiority (usually above 70%) in the regions the planes will pass through and in the destination region. Without control of the skies, transports become easy targets for enemy fighters.

When designing paratrooper divisions, less is more. A division that is too large (with high combat width) will have an immense Weight, requiring a fleet of planes that your industry might not be able to produce. The ideal is to create smaller, agile divisions to capture cities, or focus on adding essential support companies (like Engineers and Support Artillery) to ensure they survive until the main ground army can reach them. Remember: landing causes an immediate loss of Organization; never drop troops directly onto an enemy tank division, or they will be annihilated before they even hit the ground.

Thank you for reading this far. This is, without a doubt, the longest guide I've ever made. I confess I learned a lot while making it and discovered many things while reading and preparing it. I hope it helps; knowing these statistics is of utmost importance for playing the game well.

You have now progressed through the essential technical glossary of Hearts of Iron IV's modern design philosophy. As established, this is no longer a game of simple military aggregation, but one of intricate logistical and industrial optimization.

The modern battlefield is won not just through brute force, but through the intelligent management of dependencies:

• Efficiency is King: High attack means nothing if your unit melts from low Reliability or runs out of Fuel.
  
• Synergy Matters: A balanced division template ensures that high Armor forces the enemy to produce expensive Piercing, while high Organization ensures the unit utilizes its Soft/Hard Attack effectively before morale collapses.
  
• Logistics is Paramount: Without proper Supply throughput and robust Recovery Rate, even the best tanks become slow, hungry paperweights.

Thank you for reading, and I wish you strategic success on the front lines!

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