Game concept
Great Holy War
The game also links it as Great Holy Wars.
From the game's encyclopedia
A Great Holy War is a special type of War that only the Head of Faith of certain Faiths can declare, with the goal of bringing an entire Kingdom under the rule of their Faith.
Great Holy Wars target all Rulers of another Religion within a chosen Kingdom, forcing them to defend together. If victorious, all Titles within the targeted Kingdom will be seized and divided between the attackers.
Depending on its Doctrines, a Faith might have access to Directed Great Holy Wars, Undirected Great Holy Wars or no Great Holy Wars at all:
• The Armed Pilgrimages, Struggle and Submission, or Warmongering Tenets are required to access to Great Holy Wars in general
• Faiths with a Temporal Head only have access to Directed Great Holy Wars
• Faiths with a Spiritual Head only have access to Undirected Great Holy Wars
• Faiths without a Head of Faith cannot declare any Great Holy Wars, even if they would normally be eligible
Some Faiths have special names for their Great Holy Wars such as 'Crusade' or 'Jihad'. These Great Holy Wars differ in name only, and function as any other Great Holy War.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Great Holy War is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "A Great Holy War is a special type of War that only the Head of Faith of certain Faiths can declare, with the goal of bringing an entire Kingdom under the rule of their Faith." It covers Directed Great Holy War and Undirected Great Holy War. The game also links it as Great Holy Wars. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.