Holy Wars and Crusades are powerful tools for religious expansion and defense in Crusader Kings III. They allow rulers to wage war for religious reasons, often with the backing of their entire faith, and can lead to vast territorial gains or desperate defenses.
Initiating a Holy War
A Holy War can be declared by a ruler against another ruler of a different, hostile faith. The casus belli (reason for war) is religious in nature. To initiate a Holy War, you must have a high opinion of your religion's head (e.g., the Pope for Catholics) and meet certain opinion thresholds with your own vassals and fellow co-religionists.
- Target Selection: You can target any ruler of a hostile faith. The target's realm size and military strength will influence the difficulty.
- War Goal: The primary war goal is typically to conquer a specific county or duchy within the target's realm.
- Opinion Requirements: Your ruler's piety and opinion of their religious head are crucial.
The Pope & Crusades
For Catholic rulers, the Pope has the unique ability to launch Crusades. A Crusade is a large-scale Holy War that calls upon all Catholic rulers to participate. The Pope selects the target, and the war goal is often a significant territory, such as the Kingdom of Jerusalem. Crusades are powerful but can be challenging due to the combined might of multiple rulers.
- Papal Influence: The Pope's decision to launch a Crusade is influenced by various factors, including the political climate and the perceived threat from hostile faiths.
- Crusader Armies: Rulers who join a Crusade contribute their own armies to the war effort. These armies are often led by powerful figures.
- Crusade Rewards: Successful Crusaders can gain significant prestige, piety, and land.
Defending Against Holy Wars & Crusades
When your realm is targeted by a Holy War or Crusade, it is a dire situation. You will face the combined might of your enemies' faiths. Effective defense requires:
- Strong Alliances: Ensure you have strong alliances with rulers of your own faith.
- Well-Trained Armies: Maintain a strong standing army of Men-at-Arms.
- Fortifications: Ensure your holdings are well-fortified.
- Diplomacy: Attempt to sow discord among your enemies or secure defensive pacts.
Religious Heads & Faiths
The mechanics of Holy Wars are tied to the specific tenets of each religion. Some religions are more aggressive and prone to Holy Wars, while others are more defensive or focused on internal matters. The head of your faith plays a pivotal role in initiating and influencing these conflicts.
Piety & Opinion
Engaging in Holy Wars and Crusades can significantly impact your ruler's piety and opinion with their religious head and fellow co-religionists. Successful participation earns piety and prestige, while failures can lead to religious dissent and negative opinions.