From CK3 Wiki
Jump to navigation Jump to search
Introducing CK3 #10 - War. Pixelated Apollo will cover everything tied to war: how to fight, siege, ransom characters and win wars!
Introducing CK3 #11 - Battles. Pixelated Apollo joins us once again to tell us everything about terrain. From terrain to advantage you shan't lose another battle.

Warfare is the most straightforward way of expanding a character's Realm, taking titles by force on the battlefield. A character cannot declare war while in Debt.


Combat phases[edit]

Battles start when two armies enter the same Barony. At the start of any battle, the terrain's Combat Width decides how many troops are able to fight each other at the same time. Each battle goes through 4 phases:

  • Maneuver phase.png Maneuver Phase: The armies prepare for battle and the Commanders make their initial Advantage rolls.
  • Early battle phase.png Early Battle Phase: The armies fight and inflict damage upon each other daily and cannot retreat. If an army is defeated in this phase, all Routed Casualties become Fatal Casualties.
  • Late battle phase.png Late Battle Phase: The armies keep fighting and keep inflicting damage upon each other each day until either all soldiers on one side run out of Toughness or one side decides to retreat. If an army retreats, all remaining soldiers become Routed Casualties.
  • Aftermath phase.png Aftermath Phase: The winning army attempts to turn Routed Casualties into Fatal Casualties. When the phase ends, the defeated army moves into an adjacent Barony with all Routed Casualties and cannot be given orders until if finished traveling a couple of Baronies away, but will travel slightly faster than controlled armies.

The advantage modifier[edit]

When combat starts, the Advantage, a modifier that lasts the entire battle and increases the damage of all troops on either side, is calculated for both sides. Advantage can come from traits, terrain, buildings or the Martial skill of the Commander. Each Commander will also make a roll every 3 days in an attempt to increase their Advantage, and the roll can be affected by various modifiers and traits. Each point of Advantage increases an army's damage by +2%. Starting Advantage can be affected by the following:

  • +30 if army is defending across a strait
  • +20 if army is defending across a large river
  • +10 if army is defending across a river
  • +5 if liege is leading the army
  • -10 if realm is in debt
  • -10 if army is gathering
  • -10 if army is low on supplies
  • -25 if army is out of supplies
  • -30 if army is attacking across sea


A Siege takes place when an army attacks a Fortified Holding and outnumbers the Holding's  Garrison and is the main way of gaining War score. In order to occupy a County, all Fortified Holdings have to be occupied. Castles and County Capitals are all fortified by default. How difficult it is to besiege a Fortified Holding is determined by its  Fort Level, which can be increased by certain buildings and modifiers. The base amount of Siege Progress needed to occupy the Holding is 100, and each  Fort Level increases it by 50. Siege Progress is gained every tick, especially if the attacker heavily outnumbers the garrison or brings siege weapons.

Being attacked while besieging a Fortified Holding will make the besieger the attacker of the battle, making them lose any terrain defensive bonus.

Each siege will keep track of the defenders' supplies, average health and fortifications. During sieges, certain events can happen by default every 20 days, which can lower one of those. Walls can only be damaged if the attacking army has Siege Weapons.

Asset Stage 1 effects Stage 2 effects Stage 3 effects
Siege action supplies.png Garrison Supplies None Unit stat siege progress.png +10% One-Time Siege Progress Unit stat siege progress.png +30% One-Time Siege Progress
Siege action disease.png Garrison Health None Unit stat siege progress.png +10% Daily Siege Progress Unit stat siege progress.png +20% Daily Siege Progress
Siege action walls.png Walls None -10% Time Between Siege Events
Yes Can assault the Fort
-30% Time Between Siege Events
Yes Can assault the Fort

Assaulting the Fort will add a large amount of daily Siege Progress at the cost of casualties.

War score[edit]

War score is a measure of which side is winning a war. It ranges from -100 to +100, each point added to one side being subtracted at the same time from the other side. War score is gained by winning Battles, occupying Holdings, taking prisoners and especially having control of the Casus Belli's Objective.

Objective Bonus war score
Capturing enemy ruler +100
Capturing enemy heir +50 (primary heir)
+25 (secondary heir)
+10 (tertiary heir)
Occupying enemy capital +10

At +30 War score, the winning side can call for White Peace. At +100 War score, the winning side can enforce their demands on the losing side. Alternatively, at -100 War score, the losing side must surrender to the winning side.

War contribution[edit]

Wars where either the attacker or the defender has allies keep track of the percentage of War score that was provided by each ally's armies. When the war ends, a certain amount of  Gold,  Prestige or  Piety is shared among all allies based on their War Contribution.

If a war lasts at least 2 years and one of the allies has 0% War Contribution, it will lose -20  Opinion with the war leader and have to pay  Gold or  Prestige or promise to earn War Contribution within a year. Breaking the promise will result in losing a Level of Fame as well as -50  Opinion with the war leader.

Ending wars[edit]

Wars can end in two ways: victory for one side and defeat for the other, or with a White Peace.

If the attacker achieves victory, they benefit from the effects of the used Casus Belli. If the defender achieves victory, the attacker is forced to pay a large sum of Gold to the defender and will lose  Prestige or  Piety.

White Peace can be proposed at any point by one of the two sides and requires the other side to accept it. In case of White Peace, the attacker will lose a small amount of  Prestige or  Piety.

After a War, the allies of both sides will gain  Prestige regardless of who the victor was, based on their Contributions.

When a War ends, the attacker will gain a Truce with the defender for 5 years. If the former attacker declares war again while the Truce is active, they will lose 250  Prestige and one Level of Fame and gain -50 General Opinion for 3 years.

Offensive and defensive wars[edit]

An offensive war is one where you are the attacker. Usually, these are wars that you chose to engage in. A defensive war is one where you are the defender.

There is no prestige cost to call on an ally to assist in a defensive war. However, there is a cost for offensive wars that is based on the ally's rank:

Rank Cost ( Prestige)
Baron 750[1]
Count 75
Duke 150
King 350
Emperor 750

After 6 months have passed since the start of a war, the attacker in an offensive war will start to gain negative  Opinion with all Vassals. Every two months afterwards, their  Opinion will decrease by -1. After the war is over, the penalty will decay with the same speed. Civil Wars, defensive wars, and Great Holy Wars do not cause  Opinion loss. Faiths that have the Warmonger tenet also do not suffer this penalty.

Holy wars[edit]

Holy Wars are wars started with one of the Holy War casus belli. Unlike other wars, Rulers of the same Faith as the defending Ruler can join the war without requiring an Alliance. A Ruler targeted by a Holy War gains a character interaction to convert to the attacker's Faith in order to end the war in White Peace at the cost of 100  Piety and 3 Levels of Devotion.

Great holy wars[edit]

Great Holy Wars can only be declared by a Head of Faith whose faith has the Warmonger, Armed Pilgrimages or Struggle and Submission tenets and can only target Kingdoms ruled by a character of a different Faith. If victorious, all Titles within the targeted Kingdom are seized and divided between the attackers based on their War Contribution. Great Holy Wars can be Directed or Undirected. Great Holy Wars do not cause Vassal  Opinion loss no matter how long they last.

During Great Holy Wars, there is no option for White Peace and capturing and imprisoning the opposing war leader or its Heir will not grant War score. If the attacking Faith wins, its Fervor will decrease by -30 while the defending Faith's Fervor will increased by +25%. If the defending Faith wins, the attacking Faith will lose -25 Fervor.

Characters who contribute to a Great Holy War will gain the Trait crusader.png Crusader trait if Christian, Trait mujahid.png Mujahid trait if Muslim or Trait faith warrior.png Warrior of the Faith trait if their Religion is any other. In addition, if the character had the  Excommunicated trait, it is removed.

Directed great holy wars[edit]

Directed Great Holy Wars can be declared by Temporal Heads of Faith. If victorious, the Kingdom is granted to the Head of Faith. Rulers of the same Faith can join forces with the Head of Faith, and based on their War Contribution, may gain Piety or Titles in the conquered Kingdom if victorious.

Undirected great holy wars[edit]

Undirected Great Holy Wars can be declared by Spiritual Heads of Faith. When declared, a preparation phase starts, during which Rulers of the attacking and defending Faiths can either donate gold or pledge military support to their side.

Each Undirected Great Holy War will have a War Chest, to which characters of the attacking Faith can donate  Gold in order to receive  Piety equal to half of the amount donated. Donating significant amounts will also grant bonus  Opinion with the Head of Faith. When the preparation phase ends, 20% of the War Chest's value will be divided among all rulers who pledged military support for the attacking Faith. The rest will be divided among all rulers who pledged military support if their Faith wins.

During the preparation phase, characters belonging to the Faith of the attacker or the defender can pledge military support. Characters who pledge military support may gain a share of the War Chest's value and will end all wars against characters who also pledged military support. Characters of the attacking Faith who pledge military support can also choose a Beneficiary, a character of their Dynasty who will receive titles in the targeted Kingdom proportional to their War Contribution. Upon pledging, characters of the attacking Faith will gain Piety and the War Chest will gain Prestige and Piety depending on their Primary Title rank:

Rank Piety War Chest Prestige War Chest Piety
Baron 30 250 75
Count 60 500 150
Duke 90 1000 300
King 120 1500 600
Emperor 150 3000 1200

A character can withdraw their pledge for military support after making it, but doing so will cause them to lose one Level of Devotion.

In addition, during the preparation phase, characters who pledged military support can spend Piety to change the targeted Kingdom.

Once the Preparation Phase ends, the war starts. If the attackers are victorious, the Kingdom is granted to the attacker that had the highest War Contribution. During both war and the preparation Phase, attackers may donate Gold to the War Chest.

Unlocking Great Holy Wars[edit]

Each faith has to unlock the great holy wars before it can declare them. To be eligible, the faith must have the right doctrines, its head must exist and not be imprisoned, there must be at least 35 counties in the world following the faith, and at least ten years must have passed since another faith unlocked great holy wars. Additionally, there are requirements based on year and lost holy sites, according to the table:

Faith Minimum year Condition
Catholic 1095 Jerusalem is not held by Catholics
Catholic 1000 Byzantine Empire is not Christian (either the emperor or top liege of any of these counties: Constantinople, Ankyra, Athens, Corinth)
Catholic 800 Europe is not Christian (top liege of any of these counties: Provence, Toulouse, Paris, Cologne, Halberstadt)
Catholic - Top liege of Rome is not a Catholic
any faith 1100
any faith 800 Any two holy sites are in a realm whose top liege is not of this faith
Islam - After Christianity has unlocked, and any holy site is in a realm whose top liege is not Muslim
any faith - After both Christianity and Islam have unlocked, and any holy site is in a realm whose top liege is not of this faith


Raiding is the process of attacking the Holding of another character without requiring to be at war with them in order to gain Loot. In order to Raid, a ruler must be of either unreformed Pagan religion or Tribal government. Once a ruler has been Raided, it cannot be Raided again by the same enemy for 5 years. Holdings that have been Raided will have a torch icon above them.

Raiding is done via Raiders, armies raised in owned provinces for the purpose of Raiding that can carry loot based on the army size. Raiders cannot embark unless their culture has unlocked either the Longships or the West African Canoes Innovation. While Raiding, the army cannot move, allowing the attacked character to raise an army against the raiders if possible. If a Raider army is defeated, all Loot will be recovered.

If a Commander has raided at least 20 times, each raid has a chance to grant them the Trait viking.png Raider trait equal to the amount of times they raided.

If the raided Barony is a Ruler's Realm Capital, raiding may capture or kill courtiers or family members.

If the Liege is the army's Commander after the Holding is raided, there is a 30% chance they will gain the option to sack its County. The chance is increased to 50% if the Liege has the Trait viking.png Raider trait. Sacking the County will grant additional  Gold and  Prestige while the County will gain -40  Development Progress. It will also give the County the Recently Sacked modifier for 20 years, which prevents any Holding inside from being sacked again and gives it +20 Popular Opinion. Sacking a County will grant +10  Stress if the character has the  Compassionate or  Forgiving traits.

Maintenance cost for armies raised as raiders is reduced by 50%.

Being raided[edit]

Holdings that are raided gain the "Recently Raided" trait for 5 years, which inflicts -50% tax revenues, +50% build time, and -10% development growth.

You can recover gold from raiding armies if you defeat them in battle before they leave your territory.


Each Barony has a dominant terrain. The terrain determines the movement speed and combat width in the Barony and can affect the supply limit and development growth in its County.

Terrain Movement Speed Combat width.png Combat Width Defender Advantage County Supply Limit County Development Growth Other effects
Terrain desert.png Desert 70% 100% 0 -30% -50%
Terrain desert mountains.png Desert Mountains 50% 50% +12 -60% -50% -30% Defender Retreat Losses
Terrain drylands.png Drylands 100% 100% 0 0 -5%
Terrain farmlands.png Farmlands 100% 100% 0 +50% +20%
Terrain floodplains.png Floodplains 100% 75% 0 +35% +20%
Terrain forest.png Forest 80% 90% +3 -10% 0
Terrain hills.png Hills 80% 80% +5 -10% -10%
Terrain jungle.png Jungle 50% 70% +6 -25% -40%
Terrain mountains.png Mountains 50% 50% +12 -50% -25%
Terrain oasis.png Oasis 100% 100% 0 +10% +10%
Terrain plains.png Plains 100% 100% 0 0 0
Terrain steppe.png Steppe 100% 100% 0 0 -50%
Terrain taiga.png Taiga 80% 80% +4 -20% -5%
Terrain wetlands.png Wetlands 70% 60% +5 -25% -25% +25% Retreat Losses
+20% Fatal Casualties
Characters CharactersAttributesTraitsResourcesLifestyleDynastyCultureInnovationsModifiers
Realm & Governance VassalsCouncilCourtSchemesGovernmentLawsDecisionsTitlesBaronyCounty
Warfare WarfareCasus belliAllianceArmyHired forces
Faith ReligionFaithDoctrinesTenets
Meta ModdingPatchesDownloadable contentDeveloper diariesAchievementsJargon
  1. call_ally.0100 in game\events\interaction_events\alliance_interaction_events.txt . Barons, along with empires, cost massive_prestige_value to call (likely a bug).