Casus belli
- This article is about war justifications. For the innovation, see Casus Belli (innovation).
A casus belli, the Latin for "Cause for War", (sometimes abbreviated as CB) represents a justification for war recognized as legitimate by other characters. A ruler must have a valid casus belli before declaring war upon another ruler, and can only conquer counties specified under the Objective of the casus belli.
Contents
Objective[edit]
The Objective is the map region which is targeted by a casus belli. If the casus belli does not target a map region then the defender's Realm Capital becomes the Objective.
The attacking side gains more War Score by occupying Holdings located in the Objective region and capturing Important Prisoners. After a grace period, the defender will passively gain War Score if they holding all Counties in the Objective region.
Casus belli list[edit]
Each casus belli will cost Prestige and/or
Piety. If a character cannot pay the cost, then they can pay with a Level of Fame or Level of Devotion instead. Declaring war against a character's head of faith costs
500 Piety if the Head of Faith is
Spiritual and
100 Piety if the Head of Faith is
Temporal.
Note that:
- Pressing De Jure claims requires Innovations.
- Characters' Claims may not be valid casus belli, depending on the Faith's View on Gender.
- For Faiths with Male Dominated doctrine, female characters' Claims may not be used to seize titles from male titleholders, unless the targeted ruler is a child or
Incapable.
- For Faiths with Female Dominated doctrine, male characters' Claims may not be used to seize titles from female titleholders, unless the targeted ruler is a child or
Incapable.
- For Faiths with Male Dominated doctrine, female characters' Claims may not be used to seize titles from male titleholders, unless the targeted ruler is a child or
Casus belli costs can be removed via one of the game rules.
General CBs[edit]
Casus belli | Requirements | Cost | ![]() |
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Independence War | ![]() |
|
Attacker becomes independent | Attacker stays a vassal |
|
Seize De Jure County |
|
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Defender keeps their titles |
| |
Seize De Jure Duchy | ![]() |
|
Defender keeps their titles |
| |
Seize De Jure Titles | ![]() |
|
Defender keeps their titles |
| |
Claims |
|
|
|
Defender keeps their titles |
|
Subjugate | ![]()
|
|
Attacker vassalizes the defender | Defender stays independent |
|
Raid for Captives | ![]() |
|
Attacker imprisons 3–5 of the defender's courtiers | Attacker gains no prisoners |
|
Excommunication War |
|
None | Defender is deposed (i.e. succession happens as though the character had died) | Defender keeps their titles |
|
Ducal Conquest of County |
|
Attacker gains the target county | Defender keeps their titles |
| |
Forced Vassalization | ![]() |
Attacker vassalizes the defender | Defender stays independent |
| |
Laudably Conquer County |
|
|
Attacker gains the defender's titles | Defender keeps their titles |
|
Mongol Invasion of Empire |
|
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Attacker vassalizes all rulers in target empire within defender's realm whose religion is more tolerated by attacker than defender's, and gains all other counties | Defender keeps their titles |
|
Restore Imperial Province | None | Attacker gains all land in the target duchy within defender's realm | Defender keeps their titles |
|
Conquest CBs[edit]
The following CBs are only available to rulers who either have clan or tribal government, an unreformed faith, or their faith has the Warmonger or Pursuit of Power tenets.
- If the war ends by enforcing demands, the attacker will gain the target title and fame equal to the war contribution share.
- If the war ends by white peace, the defender keeps the target title and the attacker loses 75
prestige.
- If the war ends by surrender, the defender's keeps the target title and the attacker must pay
gold and gain +25 faction discontent.
Holy War CBs[edit]
The following CBs will cause a holy war instead of a regular one. They require the faith to be organized and to not have the Pacifism or Dharmic Pacifism tenets, and can only target rulers whose faith is considered hostile or evil. Vassals may only declare holy wars if they are of the same faith as their liege.
- If the war ends by enforcing demands, the attacker will gain all titles held by rulers of different faith and vassalize all rulers of the same faith in the target region.
- If the war ends by white peace, then the defender keeps all their titles and the attacker loses
50 piety.
- If the war ends by surrender, then the defender keeps all their titles, its faith gains
fervor equal to the attacker's cost, and the attacker must pay
gold and gain +25 faction discontent and −15
vassal opinion for 5 years.
Objective rank | Required level of devotion | ![]() |
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Dutiful | 1 | 100 | 80 | 100 | ![]() |
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Faithful | 2 | 200 | 160 | 200 | ![]() |
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Paragon of Virtue | 5 | 750 | 600 | 500 | ![]() |
Migrate to Pannonia[edit]
Migrate to Pannonia is a unique casus belli with special mechanics that can only be used once per game by characters of Táltosist faith who make the Prepare to Cross the Carpathians decision against characters in the Pannonian Basin region. If the Hungarian Migration game rule is set to Immediate the game will start with the casus belli being used by Grand Prince Álmos Ügyekfi of the Mogyër Confederation against King Boris of Bulgaria.
If the war ends in white peace, the defender keeps his or her titles. If it ends in surrender, the attacker's factions will also gain discontent. If the war ends by enforcing demands however it will have the following effects:
- Attacker gains all titles held by the defender in the Pannonian Basin region
- Attacker gains the Grand Principality of Pannonia title, and any Principality titles with de jure capitals in the captured territory.
- Any other kingdom title held by the attacker is destroyed
- Any held title that is not within the de jure realm of Grand Principality of Pannonia is given to another character
- All vassals that are not within the de jure realm of Grand Principality of Pannonia become independent
- All controlled counties convert to Mogyër culture and Táltosist faith
- All previously controlled counties convert to Pecheneg culture
When the casus belli is used it will spawn the following army for as long as the attacking character lives:
Years | ![]() |
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---|---|---|
867-889 | 3000 | 2000 |
890-904 | 5000 | 3000 |
905-910 | 6000 | 4000 |
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