Manual - Steam

Vassalage
Your greatest asset is your independence. If you give it up, you are then ruled by another
kingdom. However, sometimes it is better to have a strong protector.
Diplomatic Actions
Depending on your kingdom’s state different diplomatic options are open to you.
At peace
When you are at peace with the kingdom with which you are negotiating, you can
offer a gift, propose a wedding or propose a trade agreement. You can also demand
an attack on another kingdom or that they break off relations with another kingdom.
Of course, you can also choose to break off all relations or declare war, which will allow
you to attack enemy buildings or armies. If you break off relations, your Kingdom
Power will drop.
Existing Trade Agreement
When you trade with another kingdom, you have the same options as if you were at
peace, except that you can now offer a Pact of Non-Aggression.
Existing Pact of Non-Aggression
When you have a Pact of Non-Aggression, you have the same options as if you were at
peace, except that you can now offer an Alliance Pact. If you break your agreements,
your Kingdom Power will drop.
Existing Alliance Pact
If you are allied with the kingdom with which you are negotiating, you can invoke your
alliance to make him attack a kingdom with which you are at war.
Being Vassal
If you are vassal to another kingdom, the only option you have is to declare independence.
This means you are automatically at war with your former overlord but you get
full access to negotiate with this kingdom.
At war
If you are at war, you can only propose a peace agreement.
White Peace
If you feel that you and your enemy are equally matched, you can propose a white
peace. This means that the war will end immediately without further repercussions.
Tribute
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If one side performed much better than the other in a given war,
they may want a certain tribute before signing the peace agreement.
The tribute is in the form of one or several diplomatic assets.
You can demand or offer tribute.