Protect Vassals – A Conditional Join Expansion

Compatible with 1.19 (latest on June 16, 2026)

Update Hierarchy of Lords (v0.2, June 20): I reworked the mod and now the entire chain of lieges may be summoned to war, not just the overlord as described below (I will detail this further later, updating the mod description; below is a summary of the rework).

In short: Each liege will only not join unless (conditionality) it goes against the balance of modifiers already defined below (each will decide for themselves) or the liege considers that the troops of the attacked vassal (and those of the lieges already summoned, if any) are already more than enough for the war (if they are twice as strong as the enemy and their allies who could potentially join).

If the liege is a player, they will receive a personalized call to war (conditionality); if they have a liege above them, that liege will consider that you should join the war in the force calculation, and may join before you. If the player is a vassal, there won’t be many differences in the mechanics compared to what happens with an AI vassal in this mod, except that the player will be able to summon other lieges during the course of the war (same requirements, it’s not a bypass), not being restricted to the automatic summoning at the start of the war.

Future updates will include any necessary fixes and GUI enhancements where appropriate and possible. Enjoy the game!

Please read (still in testing phase):

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• Expand the "Conditional Join" law to effectively allow the Overlord to join the defensive wars of his vassals, keeping the vassal as war leader ("be quick").
• Allow both the Player and AI ​​to protect their vassals without having to wait;
• Allow both the Player and AI to summon their overlord to war.
• Allow both the Player and AI to protect and be protected against adventurers of hostile faith (if hostile to both player and ai).

1. If the overlord is an AI, it will join automatically, provided a balance of modifiers is positive;
2. If the overlord is a Player, you will still have to use the "Protect Vassal" interaction;

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1. The original modifiers present in the tributaries defense are retained;
2. Added: (+) Huge incentive for AI to defend its vassals, practically guaranteeing that they will join forces.
3. Added: (+) Minor incentives for AI to defend its vassals if it has the brave, honest, just or wrathful trait (if the suzerain is at peace).
4. Added: (-) Minor disincentives for AI to defend its vassals if it has the craven or lazy trait (doubled if the suzerain is at war).

   

(I’m still not sure if this works, it seems hardcoded, but the UI says it does).

1. The original modifiers present in the tributaries defense are retained;
2. Added: Custom modifiers mentioned in the topic above, with the exception of vassals.
3. Added: (+) Standard incentive for AI to defend its tributaries, decreasing the chance of attacks against them.

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• Still in the testing phase, it’s working well, but bugs are expected, especially in total conversion mods;
• Compatibility (Modified interaction): join_vassal_war_interaction;
• Other mods:
  LotR: Grace of the Firstborn.

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"Charlemagne and Hildegard" by Antoine-Jean Gros.