Unam Sanctam

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This article is accurate for the latest versions of EU3, Napoleon’s Ambition, In Nomine, Heir to the Throne and Divine Wind.

Unam Sanctam IN.gif / Deus Vult EU3.gif
Culture national idea
Unam sanctum.png
Unam Sanctam IN.gif / Deus Vult EU3.gif
Introduced EU3.gif
Requirement(s) None
Effects Do not need a casus belli to declare war on heathens
Effects since IN.gif Do not need a casus belli to declare war on heretics
Effects since HTTT.png grants casus belli – see text
Papal influence: +5% yearly

Unam Sanctam is a national idea, which was formerly called “Deus Vult” in the original EU3, but was renamed with In Nomine.

Divine Wind and Heir to the Throne

Unam Sanctam grants the following casus belli:

  • Cleansing of Heresy – against countries with different religion within the same religious group
  • Holy War – against countries of another religious group - if it’s before 1650 A.D. and this country is Christian or Muslim.
  • Religious Liberation – against countries of another religious group which owns a province of this country’s religious group - if this country is not Christian or Muslim

For Catholics it also provides additional 5% papal influence yearly.

Ingame description

‘Therefore, of the one and only Church there is one body and one head, not two heads like a monster.’ - Pope Boniface VIII[1]

Related missions

Related decisions

Related missions

  • Chance ×10.0:
  • Chance ×5.0:
  • Chance ×2.0:

In Nomine

Its main effect is to remove the stability penalties for declaring war on heretics.

For example: Catholic realms consider Protestant, Reformed and Orthodox realms to be heretical, while all other religions are seen as heathen. This means that a nation with Unam Sanctam can declare war without two of the often-seen penalties when declaring war: -2 stability for lack of casus belli and -1 stability because the target nation is in the same religious group.

Unam Sanctam is useful for warmongering realms, especially if they have a rather rare religion. Sometimes, in the aftermath of the Reformation in Europe, there will end up being a single realm with, say, the Reformed faith. If they adopt Unam Sanctam, it will enable them to wage war against all of Europe -if desired- with no need for casus belli at all. Another fine example is Japan. Since they start as the only Shinto nation, Unam Sanctam will allow them to attack everyone without a casus belli.

Note that while Unam Sanctam does remove the casus belli stability hit, it does not undo the reputation hit you incur for declaring aggressive war without cause unless you have a valid casus belli through other means. Any wars you declare without a casus belli will be called the nth War of $Country$ Aggression, and your nation gains 2 points of reputation for declaring war without cause. Declaring war with Casus Belli only involves a single point of reputation. See the article on reputation for more details.

NA and EU3

In EU3 and Napoleon’s Ambition, Deus Vult removes the stability hit for declaring war on heathens.

So for example: Catholic Castille would get no stability penalty for declaring war on Sunni Algiers. With In Nomine, the no-stability hit for heathens was made automatic for all nations, and the idea was replaced by Unam Sanctam.

See also


  1. Pope Boniface VIII (*1235 – †1303)