CK3 DatabaseCrusader Kings III · 1.20.0.3 “Crozier” · unofficial

Casus belli · Event wars

Great War of Defiance

The war is called “Great War of Defiance against the defender”

Great War of Defiance is a casus belli in Crusader Kings III (event wars). If the attacker wins: The defender is imprisoned by the attacker, humiliated, impoverished, and loses all Landed Titles. Their Vassals, Counties and Tributaries become independent. If the defender wins: Defeated Independent Nomads become the defender's Obedient Vassals. All other Truces with the defender are removed. The defender becomes Greatest Of Khans and receives powerful bonuses towards universal conquest. The war goal is worth 50% war score. Patch 1.20.0.3, from game/common/casus_belli_types/09_mpo_wars.txt.

Quick answers (1)
What do you get for winning a Great War of Defiance war in CK3?
The defender is imprisoned by the attacker, humiliated, impoverished, and loses all Landed Titles. Their Vassals, Counties and Tributaries become independent (patch 1.20.0.3).

How the war ends

Attacker wins

The defender is imprisoned by the attacker, humiliated, impoverished, and loses all Landed Titles. Their Vassals, Counties and Tributaries become independent.

Defender wins

Defeated Independent Nomads become the defender's Obedient Vassals. All other Truces with the defender are removed. The defender becomes Greatest Of Khans and receives powerful bonuses towards universal conquest.

If the war becomes invalid

The … has no purpose: the defender cannot become Greatest Of Khans.

Who can declare it

The game shows no text of its own for these conditions; the script is below.

Every event wars war (the group's allowed_for_character) (1 line of game script)
herders_and_tributary_constraints = yes

As written in game/common/casus_belli_groups/00_casus_belli_groups.txt.

Defender (allowed_against_character) (8 lines of game script)
is_landed = yes
any_character_situation = {
	any_participant_group = {
		participant_group_type = nomad_rulers_capital
	}
}
government_has_flag = government_is_nomadic
highest_held_title_tier >= tier_empire

As written in game/common/casus_belli_types/09_mpo_wars.txt.

Source: game/common/casus_belli_types/09_mpo_wars.txt and the English localisation, Crusader Kings III 1.20.0.3. “The attacker”, “the defender” stand where the game names the character; “…” marks other words it fills in during play.