Age of Wonders: Planetfall Diplomacy Guide – Vassalage, Casus Belli, Declaring War

Diplomacy in Age of Wonders: Planetfall can be practiced by commanders on the planet after they meet. Diplomacy allows players to make treaties & pacts, trade resources, or declare war. Players can conclude to treaties that are formal agreements, along with making pacts, trade resources, and even declare war when they start engaging in diplomacy. For the games which do not have teams enabled, most of the diplomacy tactics are disable.

Age of Wonders: Planetfall Diplomacy

The intensity or the factor of mutual collaboration is represented by the Diplomatic State that also affects opinions, race relations, and reputation.

An increase of base opinion and the ability to make better treaties or formal agreements are observed with an increase in the Diplomatic State amongst two commanders.

The Diplomatic States of a player cause a change in their reputation. Resorting to wars and refuting pacts lower the reputation whilst the practice of keeping better Diplomatic States causes an increase in reputation.


  • Share Intelligence Treaty
  • Allies Can Be Called Into Any War
  • Allows Allied Victory
  • Opinion: +400
  • Reputation: +150
  • Race Reputation: +200

Defensive Pact

  • Unlocks Share Vision Treaty
  • Unlocks Alliance
  • Members Can Be Called Into Defensive Wars
  • Adjacent Stacks Can Join Each Other in Battle
  • Opinion: +100
  • Reputation: +250
  • Race Reputation: +100

Non-Aggression Pact

  • Unlocks Open Borders Treaty
  • Unlocks Good Neighbors Treaty
  • Unlocks Defensive Pact
  • Opinion: +50
  • Reputation: +100
  • Race Reputation: +50

Can declare war without any turn delay:

  • Opinion: 0
  • Reputation: 0
  • Race Reputation: 0


  • Unlocks Truce Treaty
  • Unlocks Call to War Action towards Other Commanders
  • Unlocks Demands and Offers of Vassalage


A preceding unavailable Diplomatic State that is provided during the war is known as Vassalage. There are only a few options that a commander in a Vassalage State has:

  1. Only the Overlord Can End the Vassalage by Declaring War
  2. Only the Overlord Can Call the Vassal to War and the Vassal Is Forced to Accept
  3. Vassal Commanders Can No Longer Denounce or Warn Other Commanders
  4. Treaties Cannot Be Broken by the Vassal
  5. The Vassal Is Freed If the Overlord Is Defeated

Casus Belli

Points represented to discredit commanders and declare war upon them are known as Casus Belli.

You need a proper cause to declare war on a commander because if you don’t you would not gain popular support, this is the importance of Casus Belli. Popular Support is directly proportional to the quantity of Casus Belli.

The way to obtain a Casus Belli is getting a commander provoked by the other. This can be done by doing the covert operation to forge Casus Belli or it can be done on its own when a commander has a low reputation or race relation.

War or negotiation is the solution for Casus Belli. Automatic Casus Belli is received by having a low reputation or race relation with the race of the opposing player. They cannot be forgiven through negotiation but can be used in war declarations.

Popular Support
The supportiveness of the army of a commander’s population is represented by Popular Support. Greater Popular Support translates to decreased unit upkeep, greater morale units, and increased happiness. Popular Support takes a hit if war is waged without Casus Belli and vice versa. It resets after the war.

The opinion will be reduced by 50 for every Casus Belli against a commander. 20 is subtracted from the grudge opinion each caused by Casus Belli each turn in case negotiations revoke it.

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