Historical Army Combat Proficiency

In vanilla Hearts of Iron IV, two land divisions using the same template and the same generation of equipment will often perform almost identically, regardless of which country fields them.

Historically, however, weapons and organization were only part of combat effectiveness. The same rifle, tank, artillery piece, or division template could produce very different battlefield results depending on the soldiers, crews, NCOs, junior officers, training institutions, discipline, education level, unit cohesion, and small-unit tactical culture behind them.

This mod introduces a new national system: Army Combat Proficiency.

Army Combat Proficiency is a human-factor modifier representing the training, discipline, education, cohesion, NCO quality, small-unit tactics, and battlefield adaptability of a country’s land forces.

It affects all land forces. Infantry divisions, armored divisions, motorized formations, mechanized units, cavalry, and special forces are all influenced by the institutional quality of the army that fields them.

1. What It Affects:

Army Combat Proficiency modifies three core land combat statistics:

-Army Attack
-Army Defense
-Army Organization

These values represent how effectively a formation attacks, holds ground, and maintains cohesion under battlefield pressure.

For example:

A country with 1.25 Army Combat Proficiency receives:

+25% Army Attack
+25% Army Defense
+25% Army Organization

A country with 0.75 Army Combat Proficiency receives:

-25% Army Attack
-25% Army Defense
-25% Army Organization

2. Historical Starting Values:

Every country receives an initial Army Combat Proficiency coefficient based on its historical military institutions, training quality, tactical culture, and readiness before the war.

Examples:

Germany: 1.25
Represents superior tactical doctrine, strong junior leadership, high training standards, and the legacy of Auftragstaktik.

Finland: 1.20
Represents a highly capable small army with strong discipline, fieldcraft, cohesion, and small-unit effectiveness.

Japan: 1.15
Represents strong discipline, infantry endurance, and aggressive tactical culture, while preserving early-game balance.

Regular Armies: around 1.00
Represents the baseline for a standardized army.

Chinese warlords: 0.75
Represents weak training systems, limited professional cadres, structural fragmentation, poor cohesion, and inconsistent combat readiness.

Other countries are distributed across the scale according to their historical army quality and military institutions.

3. Dynamic Modernization:

Army quality is not fixed forever.

Countries can improve their Army Combat Proficiency through combat experience, training reform, and institutional modernization.

Upgrade Cost: 300 Army Experience

Upgrade Amount: +0.05 Army Combat Proficiency

Maximum Proficiency: 1.50

This allows weaker armies to gradually overcome their initial disadvantages, while already proficient armies can further refine their battlefield effectiveness.

4. AI Support

AI-controlled countries will automatically improve their Army Combat Proficiency when they accumulate enough Army Experience.

This ensures that the system remains active throughout the campaign and that major powers continue to develop into the mid and late game.

5. Design Philosophy

This mod does not represent equipment quality, industrial capacity, logistics, air power, naval capability, or high-level grand strategy.

It focuses on the human and institutional side of land warfare:

-Education and literacy
-Physical conditioning
-Basic training standards
-Discipline and cohesion
-NCO and junior officer quality
-Small-unit tactical proficiency
-Initiative and battlefield adaptability
-Crew coordination and unit-level combat execution
-The ability to operate weapons effectively

The goal is to add a historically inspired army-quality layer to Hearts of Iron IV, making national land forces feel more distinct without removing the ability of every country to reform, modernize, and improve over time.