Subject nations

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Subject nations, or vassals, are countries in a subservient relationship to another state, paying tribute or fulfilling commercial or military obligations to their overlord in return for protection from other states. They are restricted in their diplomatic actions, especially with countries other than their overlord, and certain subject types can be integrated directly into their overlord.

General rules

Each kind of subject state is different but there are general guidelines all subject states must follow.

  • All subject types pay some sort of resource to their overlord, with the exact type and amount depending on the subject type.
  • Other than for trade, a subject can never enter into diplomatic agreements with other countries.
  • When a country becomes a subject, all their agreements with other countries are broken.
  • The overlord and subject will always have military access to each other's territory.
  • Subjects have military access to the territory of other subjects of the same overlord.
  • A subject can always leave a subject relationship by declaring war on their overlord. They cannot declare war on any other country.
  • Overlords will always be called to war and become the war leader if one of their subjects are attacked.
  • If the overlord and its subject state are both involved in the same war, the overlord can always transfer occupation to and from any of their subject states and can annex territory on their behalf for half of the Aggressive expansion.png aggressive expansion (compared to if the overlord was annexing the territory directly).

Acquiring subjects

There are many ways to acquire new subjects over the course of the game:

  • The Release subject.png Release Subject action in the Nation overview screen will allow you to release a new client state out of any non-capital province. This country will be dynamically created and take on the name, culture, and religion of its capital territory.
    • Flag of Syracusae Syracusae has a special Create mercenary state.png Create Mercenary State action that instead allows releasing a mercenary state out of any non-capital city. This is the only way to create new mercenary state subjects.
  • Waging war and defeating a country will allow for Become subject.png forcing vassalization of existing states in a peace deal. A country can be vassalized if its capital is occupied in a war, with a smaller Warscore cost warscore cost and halved Aggressive expansion.png aggressive expansion compared to directly annexing the country. Defeated countries can be forced into any subject type that they and their future overlord fulfill the potential for, with all subject types being equivalent in terms of warscore cost and aggressive expansion gain. Like all other peace deal demands forcing vassalization is not possible if the warscore cost exceeds 100, e.g. if the realm is currently too large.
  • A more diplomatically inclined nation can offer vassalization through various diplomatic influence actions. This requires that the potential conditions are met and that the target country have at least Opinion 100 opinion of the potential overlord, but is generally unlikely to be accepted unless the target is much weaker than, and has a very high opinion of the potential overlord. Targets are more likely to accept becoming certain subject types (such as tribal vassal or tributary status) over others (including feudatory and client status).
  • Countries can use the Demand Subject Transfer diplomatic action to peacefully take existing subject states of other nations if they are disloyal, and the target has at least 80 opinion of their potential new overlord. As with offering vassalization, military strength and the target's opinion of their potential new overlord are important.
  • Many events and missions also offer opportunities to get new subjects, both from releasing new countries out of currently owned territory (such as the many colony and feudatories available in the Flag of Carthage Carthaginian mission tree) or from vassalizing existing countries (such as in the Italic League mission/event chain of the Flag of Rome Roman mission tree). This is the only way to create new colonies.

Subject nation types


  • Requirements: These conditions must be true for this relationship to be possible.
  • Payment: The subject makes this payment to the overlord on a monthly basis.
  • Dip. slot: Whether a subject of this type contributes to the overlord's diplomatic relations limit.
  • Join wars: Whether a subject of this type is automatically called into the overlord's wars, if it is loyal.
  • Integrate: Whether the overlord can integrate the subject.
  • Break: Whether the subject can break the relationship through a diplomatic action (i.e. without a war).
  • Limit dip.: Whether the overlord limits the subject's diplomatic interactions.

Subject type Requirements Tribute income.png Payment Diplomatic relations.png Dip. slot Join wars Integrate.png Integrate Break Limit dip. Effects
Tributary None Cost 15% of income No No No Yes Yes None
  • Overlord is NOT a Tribe
  • Overlord has at least 20 territories
  • Subject has no more than 10 territories
  • Subject and overlord are in the same culture group
Manpower.png 15% of monthly manpower gain No Yes Yes No Yes Subject:
  • Army maintenance cost.png −10% Army Maintenance Cost
  • Pop citizen happiness.png −5% National Citizen Happiness
Tribal vassal
  • Subject is a tribe and overlord is not
  • Overlord's capital civilization value is higher than in the subject's capital
  • Overlord has fewer than 10 tribal vassals
Manpower.png 15% of monthly manpower gain No No No Yes Yes Overlord:
  • Pop tribesmen happiness.png +3 National tribesmen happiness


  • Civilization.png +10 Max civilization
  • Global monthly civilization.png +0.01 Monthly civilization change
Satrapy Cost 25% of income Yes Yes Yes No Yes Overlord:
  • Legitimacy.png +2% Monthly legitimacy
Client state
  • Neither subject nor overlord is tribal
  • Subject has fewer than 150 territories
Cost 25% of income Yes Yes Yes No Yes Subject:
  • Popularity.png −5% Ruler popularity gain
  • Commerce value.png +10% National commerce income
  • Can only export to overlord.
  • Only by event/mission
Cost 15% of income No No No No Yes Overlord:
  • Commerce value.png +5% National commerce income


  • Commerce value.png +10% National commerce income
  • Loyalty.png +25 Loyalty to overlord
Mercenary State
  • Only through the unique Flag of Syracusae Syracusae Create mercenary state.png Create Mercenary State action
Cost 10% of income Yes Yes Yes No Yes Overlord:
  • Mercenary maintenance.png -3% Mercenary Army Maintenance


  • Global manpower modifier.png +12.5% National Manpower
  • Army maintenance cost.png -20% Army Maintenance Cost


Perhaps the most basic subject type in the game is the tributary. This is a loose relationship where the subject is simply looking for protection in exchange for tribute. Unlike most other subject types the subject can at any time cancel a tributary relationship, the only risk being that the former overlord will get a casus belli for the slight on their honor.


A feudatory is a state that has obligated itself to follow the lead of a larger and more influential country in the same culture group. Historically these are countries that would often have been part of some sort of league with their overlord’s other subjects, in many ways this is a privileged subject type, if one with large obligations.

Feudatories provide manpower to their overlord and are expected to take part in their wars. Historical examples are the Roman Socii, the Punic cities of North Africa under Carthage, or the city leagues in Aegean under the Antigonids in Phrygia.

Tribal vassal

A tribal vassal is a tribal kingdom, chiefdom or federation that has a close relationship to a nearby stronger civilized state. For the tribal state this means a significantly easier route towards civilizing, as it will increase both the countrywide level of civilization and the growth of it in all their territories.The tribal state in turn pays with its manpower to the overlord who will also promise to protect them. Historical subjects of this type would be the Numidian kingdoms to Carthage and various states on the border with Rome. When a vassal tribe adopts a civilised form of government it will instead become a tributary.

Client state

Client states are in some ways more tightly integrated with their overlord, but unlike the feudatories they are not necessarily of the same culture and they don’t enjoy a privileged status in the same way. Client states may be created from the player's provinces in the Nation Overview. A client king is separated from a governor mostly by his level of autonomy and having local ties to the ruled country.


Satrapies are a special type of subject that is only available if the junior party belongs has Persian military traditions. A satrap is in some ways similar to a governor but is expected to have greater authority, bigger obligations, and a more imposing realm. As having powerful satraps is an expectation in the east a few of them will also help with maintaining the legitimacy for their overlord kingdoms. Flag of Bactria Bactria, Flag of Parthia Parthia, and Flag of Arachosia Arachosia start off as satrapies of the Flag of Seleukid Empire Seleukid Empire, while Flag of Cappadocia Cappadocia starts as a satrapy of Flag of Phrygia Phrygia.

Satrapies are notoriously independent minded and troublesome. Events will periodically require interacting with to keep satraps happy.


Colonies represent subjects descended from the a mother nation that have a largely mercantile relationship with their overlord. Like tributaries, they neither provide manpower nor can be called into wars, but importantly each colony also provides a boost to the Commerce value.png commerce income of the overlord that usually far outstrips their direct tribute, and so can be highly advantageous to establish. Colonies can only be created through certain options on the Flag of Carthage Carthaginian mission trees.

Mercenary state

A Mercenary state is a particular type of client state that has been created by granting control of a city to a mercenary company, much like the historical 20px Mamertine Republic. As well as fighting alongside their overlord, each mercenary state will also reduce the overlord's costs when hiring other mercenary companies. As well, if the overlord is a Monarchy with the Mercenary Contract Law enacted, the overlord can use Elect New Leader Character Interaction to replace their current leader with that of the mercenary state at the cost of some stability, much like Agathokles himself once did. Mercenary states can only be created through the unique Flag of Syracusae Syracusae Create Mercenary State action, which represents the rich mercenary-using traditions of the Siceliotes.

Subject loyalty

Each subject has a Subject loyalty.png loyalty value towards its overlord, visible in the diplomacy screen. This value modifies how much tribute is actually sent to the overlord and whether or not they will support and join rebellions and civil wars against the overlord.

Subject loyalty is a value between 0 and 100, where 100 signifies total loyalty.

Below a loyalty of 33 a subject state is considered disloyal, with the following effects:

  1. This reduces the tribute pays to overlord, sclaing up to 50% (at 0 loyalty)
  2. If a rebellion happens of this culture the subject will join that revolt. If the subject has a different culture group than its overlord then it will also count towards the percentage of pops in disloyal provinces that determines whether or not the country is at risk of rebellion.
  3. If a civil war happens and a subject is disloyal, it will join the revolting side.
  4. A disloyal subject will never accept an offensive call to arms.

Loyalty is affected by many factors, with the most important being the subject's Opinion opinion of the overlord, the relative size of its army, and the current Aggressive expansion.png aggressive expansion of the overlord. Laws, diplomatic stances, national ideas, inventions, military traditions, and many event/mission modifiers can also affect subject loyalty.

Integrating vassals

Only the more closely associated subject types - as a rule, those that can be called to war - can be integrated, including feudatories, satrapies and client states. Other subject types, including tributaries and tribal vassals, cannot be integrated or annexed without first breaking or changing the existing subject relationship.

Starting integration requires that the vassal has at least Opinion 190 opinion with its overlord. The cost of integration is equal to its Population.png population and is always at least 10. Integration progresses by a base of 0.25 each month, which can be increased by 0.05 per point of Diplomatic reputation.png diplomatic reputation, 0.25 with the Stance vassaling.png Domineering diplomatic stance, 0.30 with the monarchy Political influence.png King of Kings Law, 0.05 per country rank, 0.10 for the Silk silk capital bonus and 0.05 for the export bonus, 0.10 with Flag of Rome Roman heritage, and by varying amounts with different event/mission modifiers.