Terrain

This article is considered accurate for the current version of the game.

While we do quite a lot of things at the state-level, we still have terrain defined per actual province.

Different types of battalions have either penalties or bonuses in terrain to attack, defence or movement, compared to a generic Infantry. A few examples. Cavalry has a minor -5% attack penalty in most rough terrain, while Mountaineers gets a movement bonus in hills & mountains, as well as attack and defence bonuses.

Unit-specific penalties that combine negatively with terrain penalties, creates some pretty bad situations. ie, attacking a mountain with heavy armor is NOT a good idea.

Generals can get traits to give bonuses in different terrains, for example desert fox, ranger, hill fighter, jungle rat, mountaineers and swamp fox.

Types

The terrain-system is completely scriptable as in all Clausewitz games, but the terrains in Hearts of Iron IV is as follows.

Plains

• Baseline terrain, so no modifiers, as everything is relative to this.​

Forest

• 50% added to time to move through.
• 20% penalty to attack.
• 20% smaller combat width.
• 10% better protection against enemy air superiority.​

Hills

• 50% added to time to move through.
• 20% penalty to attack.
• 33% smaller combat width
• 5% better protection against enemy air superiority.​

Mountains

• 100% added to time to move through.
• 40% extra attrition
• 66% smaller combat with
• 40% penalty to attack
• 10% better protection against enemy air superiority.​

Urban

• 20% added to time to move through.
• 30% penalty to attack​

Jungle

• 50% added to time to move through.
• 50% extra attrition
• 25% smaller combat with
• 30% penalty to attack
• 25% better protection against enemy air superiority.​

Marsh

• 100% added to time to move through.
• 80% extra attrition
• 25% smaller combat with
• 40% penalty to attack​

Desert

• 5% added to time to move through.
• 30% extra attrition​