Subject nation

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The subjects interface panel image as of patch 1.18

Subject nations are semi-independent subordinate nations that surrender their economic, diplomatic and/or military power to another country in exchange for protection by their overlord. It is possible to see a subject's nation information by selecting the country icon on the subjects tab. The types of subject nations range from the primarily economic Subject tradecompany icon.pngTrade company to the military-focused March icon.pngMarch. All subjects (except trade companies) have a Liberty desire.pngliberty desire that determines their loyalty towards their liege.


Main article: Vassal

Vassal.png Vassals are the most basic form of subject nations. They are required to pay a portion of their Income from vassals.pngtax income to their overlord but do not transfer Trade power.pngtrade power to their overlord like other particular subject types unless the overlord is a merchant republic. While vassals may have control over their own territory and military, they also automatically join any conflict their overlord enters into.

Vassalization can occur militarily by forcing it upon a defeated enemy in a war. Diplomatic vassalage can occur if a military alliance exists and relations are high. Vassals cannot declare war, and automatically fabricate claims against their overlord's rivals and any other hostile nations. Vassals with over 50% Liberty desire.pngliberty desire can request a support of independence from other nations, and break free through an independence war.

After a nation has been a vassal of another country for at least ten years, their overlord can begin diplomatically integrating them into the overlord's domain. This results in the vassal's annexation.


Main article: March

A March icon.png march is a militaristic vassal that cannot be annexed and does not pay taxes to the overlord, but has lower liberty desire and gets significant bonuses to their armed forces.

Marches receive increased Land force limit modifier.pngland and Naval force limit modifier.pngnaval force limits, National manpower modifier.pngmanpower and Manpower recovery speed.pngmanpower recovery speed, and Fort defense.pngfort defensiveness, while also gaining decreased Fort maintenance.pngfort maintenance.

March status can be revoked and the subject turned into a simple vassal but at the cost of stability and relations loss.

Client state[edit]

Main article: Client state

Client states are highly loyal, custom vassals. They can be formed once a country reaches Diplomatic tech.png diplomatic tech level 23 from any province or provinces that the player has control over.

Generally, any province within two tiles by land can be added to a client state, including over straits. The first province that a new client state is given is automatically designated as the capital, and the Culture icon.pngculture in that province will become the primary culture of the new client state. The client state will have its creator's state religion.

It is possible to customize the flag and the name of a client state based on a set of flag templates and images.

Personal union[edit]

Main article: Personal union

Junior partners in a personal union share the same ruler as that of the leading country. Like vassals, junior partners of a personal union will automatically go to war if their overlord does, but they do not have to provide their overlord with a percentage of their monthly income, and only get a small +10 Icon diplomacy relations.png relations boost with their overlord.

Personal unions can occur when a ruler dies without a legal heir. In this case, if a royal marriage partner shares the same dynasty as the deceased ruler, it becomes the senior partner in a union. A succession war may erupt between rivals or valid partners. Additionally, a claim throne casus belli can be used on nations with a disputed succession (weak or no heir) of the same dynasty that the player has a royal marriage with.

Personal union partners can be inherited or integrated provided the union has been stable for fifty years. Diplomatic integration annexes the junior partner at the cost of Diplomatic power.pngdiplomatic monarch points. Inheritance automatically annexes the junior partner with no autonomy, but occurs only upon ruler death. The probability of inheritance increases with the senior partner's Diplomatic reputation.pngdiplomatic reputation and decreases with the junior partner's Development.pngdevelopment.

A personal union can end upon the death of the senior ruler when the senior partner has either negative Prestige.pngprestige or the junior partner has a Hostile attitudenegative opinion of its senior. If this occurs, the former senior partner will get a "Restoration of Union" casus belli on the former junior partner, allowing the union to be reinstated militarily.

Some nations can get a "Restoration of Union" CB against countries that they never had a union with in the first place, such as Austria, which can receive this casus belli against Bohemia by mission and Hungary by event.

Only nations that have one of the Christian religions as their state religion are able to form personal unions.

Colonial nation[edit]

Main article: Colonial nation

Subject colony icon.png Colonial nations in the Conquest of Paradise DLC represent the distant New World colonial territories of European powers. They will automatically form once five cored colonial provinces exist inside a single colonial region. Once formed, colonial nations will take control of any province that would otherwise be owned by their overlord in a given colonial region, even if the province is uncored or would otherwise cause extreme Overextension.pngoverextension.

Colonial nations pay a portion of their Income from vassals.pngtax income to their overlord, based on the tariff efficiency. Additionally, colonial nations transfer 50% of their Trade power.png trade power to the overlord.

Militarily, colonial nations are treated as vassals, and called to arms in all wars. Colonial nations will assist in overseas conflicts with their navy, but their armies will only operate in the same continent as the colonial nation.

When created, the colonial nation's flag is generated based on the mother country's flag and the colonial region the new Colonial Nation is located in. For example, a nation in the Mexico colonial region will have a yellow flag, while one in the Eastern North America colonial region will have a light-blue one.

Trade company[edit]

Main article: Trade company

A Subject tradecompany icon.png trade company is a collection of overseas provinces that trades tax and manpower for maritime benefits.

A province in a trade company provides approximately half the Income.pngincome, no Manpower.pngmanpower, and no Sailors.pngsailors to the home country but produces double the Trade power.pngtrade power and adds 0.5 Naval forcelimit.png naval force limit. Additionally, Goods produced.pnggoods produced remains unaffected by cultural intolerance.

Trade companies may be formed by nations that belong to the Western tech group and own at least one province in any of the twelve trade company regions scattered throughout Africa and Asia. They differ from colonial nations in the Americas and Australia in that they are not separate governments, as all territories remain part of the mother country. Provinces in trade company must belong to a territory - adding them to a state will automatically remove them from a trade company. Provinces can be added or removed from a trade company at any time.


Subject tributary icon.png Tributaries are a loose form of subject relationship available to nations in the Eastern religion group, as well as to steppe hordes regardless of religion. Tributaries retain full diplomatic independence and may start wars and have subjects of their own. The overlord receives a call to arms if the tributary is attacked (unless if by another tributary of the same overlord), but does not have to accept. Each year, the overlord may demand a tribute of money, manpower, or monarch points, with the size of the tribute scaling with the development of the tributary. If the tributary pays the tribute, trust increases slightly; if it refuses, trust falls significantly.

Either party may renounce the tributary status at will. The overlord gets a one-way five year truce with the former tributary, but the former tributary may attack the overlord immediately.

Since the tributary relationship is much less onerous than that of a vassal, nations are usually much more willing to accept tributary status.


Daimyo are a unique form of vassal for the shogun of Flag of Japan Japan. They may ally with and fight other daimyo, but not foreign countries. They do not occupy a relation slot, and the shogun has several special vassal interactions for them.


In previous versions of the game, technologically backward nations could be made protectorates. Protectorates were merged with regular vassals in patch 1.20.

Liberty desire.pngLiberty desire[edit]

All subject nations have a liberty desire between 0 and 100, indicating their wish for independence.

  • Below 50 a subject state is loyal: it pays taxes/tariffs to its liege and takes an active part in all wars.
  • Above 50 liberty desire, a subject becomes disloyal, refusing to pay taxes while being unhelpful in wars by only defending its own territory. Disloyal subjects readily accept support for their independence from foreign nations and make alliances with each other, and may declare an independence war if they have sufficient strength.
  • At 100 liberty desire, a state is rebellious and will declare its independence at the slightest opportunity.

Liberty desire depends on the sum of the following factors:

  • The relative army size of the subject compared to its liege. There is +75 liberty desire for having 100% of the liege's forces, scaling proportionately (e.g. +37.5 at 50%).
    • The combined strength of all vassals, marches, and client states is used for their liberty desire.
    • The combined strength of all protectorates is also used for their liberty desire.
    • Personal union partners, daimyos, and colonial nations only consider their individual strengths.
    • Additionally, nations allied with or supporting the liberty of a subject nation will have their army strength added to that specific subject. Other subjects will not have their army strength increased, unless their independence is also supported.
  • A base modifier depending on type of subject: -25 for client states and Icon protectorate.pngprotectorates, -15 for March icon.pngmarches, +10 for Japanese daimyos; 0 for Vassal.pngvassals, Subject colony icon.pngcolonies and Personal union.pngpersonal union partners.
  • +0.25 per point of development for vassals, client states, and marches.
  • +5 for each level the overlord's Diplomatic tech.png diplomatic technology is behind the subject's.
  • -0.1 for each point of positive relations (max -20), +0.2 for each point of negative relations (max +40).
  • -50 for historical Friendly attitudefriends.
  • +50 for historical Rivalry attituderivals.
  • -3 per point of diplomatic reputation.
  • ±0.4 per point of trust below/above 50 (min -20 at 100 trust, max +20 at 0 trust)
  • +1 per point of the overlord's Icon war exhaustion.pngwar exhaustion for colonial nations.
  • -50 if recently defeated in an independence war (decreasing over time).
  • +0.2 for colonies, per point of the colonial nation's Administrative efficiency.pngadministrative efficiency.
  • +0.2 per colonies, per point of Global tariffs.pngtariff rate.

Certain ideas reduce liberty desire in subjects:

Liberty desire in subjects Traditions Ideas Bonuses Policies
  • Espionage idea 4: Additional Loyalist Recruitment
  • Influence-Offensive: Unified Army Command

Subject interactions[edit]

All subject nations are listed in the subjects tab in country interface. Subject interactions require Common Sense.png Common Sense DLC unless otherwise stated. Liberty Desire modifiers from most sources - "events and province defections" decay at 0.1% per month. Toggled liberty desire modifiers (embargo rivals, support royalists, subsidize armies, divert trade, send officers) last until cancelled.

Interaction Subjects Requirements Effect Notes
Vassal.png March icon.png Personal union.png Subject colony icon.png Icon protectorate.png Subject tradecompany icon.png
Embargo Rivals.png Embargo Rivals Yes Yes Yes Yes Yes Has at least Rivalry attitude 1 rival
  • Liberty desire.png+5% Liberty Desire
  • (Subject) embargoes overlord's rivals
Scutage.png Scutage Yes
  • Income from vassals.png+50% Vassal Income
  • (Subject) will no longer be called to wars
  • Liberty desire.png+25% Liberty Desire when disabled
  • Disabling it during a war will not call the subject to arms
  • Disabling multiple times will stack the liberty desire increase
Enforce Religion.png Enforce Religion Yes Yes Yes Yes
  • (Subject) has different Convert religion.png Religion
  • (Subject) has less than 50% Liberty desire.pngLiberty Desire
  • (Subject) has Icon diplomacy relations.png positive relations with overlord
Changes the subject's religion to that of the overlord
  • Liberty desire.png+50% Liberty Desire if subject's religion in the same religion group
  • Liberty desire.png+100% Liberty Desire if subject's religion in different religion group
Grant CoreClaim.png Grant Core/Claim Yes Yes Yes Yes Yes Core/claim has a land connection with subject or is within one sea zone of subject Core/claim is granted to the subject Requires The Cossacks.png DLC
Grant Province.png Grant Province Yes Yes Yes Yes Yes Province has a land connection with subject or is within one sea zone of subject
  • Liberty desire.png-0.5 Liberty Desire * Development.png Development
  • Province is granted to the subject
  • Cores of overlord go along with the grant
Requires The Cossacks.png DLC
Placate Local Rulers.png Placate Local Rulers Yes Yes Yes Yes Has positive Prestige.png Prestige
  • Liberty desire.png-10% Liberty Desire
  • Prestige.png-20 Prestige (for overlord)
Place Relative on Throne.png Place Relative on Throne Yes Yes (Subject) Doesn't already have same dynasty
  • Liberty desire.png+25% Liberty Desire Liberty desire.png+10% if subject in regency
  • Places overlord's dynasty on subject's throne
Fortify March.png Fortify March Yes Fort is built, paid by the overlord
Subsidize Armies.png Subsidize Armies Yes
  • 10% of the overlord's Manpower.pngmanpower is sent to the subject
  • +50 Icon diplomacy relations.png relations with subject
Support Loyalists.png Support Loyalists Yes
  • Liberty desire.png-20% Liberty Desire
  • costs 10% of the subjects income, paid by overlord
Enforce Culture.png Enforce Culture Yes (Subject) has less than 50% Liberty desire.pngLiberty Desire
  • Liberty desire.png+25% Liberty Desire
  • Changes the subject's Primary Culture to that of the overlord for 2 Diplomatic power.png per development
Siphon Income.png Siphon Income Yes (Overlord) positive Icon diplomacy relations.png relations with subject
  • Liberty desire.png+10% Liberty Desire
  • 50% Income from vassals.png of subject's yearly income, -100 Icon diplomacy relations.png relations with subject
Decrease Tariffs.png Decrease Tariffs Yes
  • Liberty desire.png-1% Liberty Desire
  • Adjusts Global tariffs.png tariffs by -5% for 25 Administrative power.png
* Available in base EU4
Increase Tariffs.png Increase Tariffs Yes
  • Liberty desire.png+1% Liberty Desire
  • Adjusts Global tariffs.png tariffs by +5% for 50 Administrative power.png
* Available in base EU4
Replace Governor.png Replace Governor Yes (Subject) Less than 50% Liberty desire.pngLiberty Desire
  • Liberty desire.png+10% Liberty Desire
  • Gives the subject nation a new leader
Choice between 4/2/2, 2/4/2 or 2/2/4
Start War in Colony.png Start War in Colony Yes (Subject) at peace, Casus Belli and no truce with target
  • Subject starts a war with natives or other colony
  • Overlord is not called in
Divert Trade.png Divert Trade Yes
  • Liberty desire.png+30% Liberty Desire
  • Overlord gets 100% of subject's Trade power.pngtrade power
Seize Territory.png Seize Territory Yes
  • (Overlord) Positive Icon diplomacy relations.pngrelations with subject
  • (subject) has less than 50% Liberty desire.pngLiberty Desire
  • Liberty desire.png+5 Liberty Desire * Development.png Development
  • Overlord seizes province
Cannot seize Capital.pngcapital
Send Officers.png Send Officers Yes
  • Liberty desire.png-10% Liberty Desire
  • Overlord pays 33% of subject's Land maintenance modifier.png army maintenance
  • Protectorate gets +20% Morale.png Land Morale and +5% Discipline.png Discipline
Promote Investments.png Promote Investments Yes
  • +50% Trade power.png Trade Power in all owned provinces
  • +.03% Inflation reduction.png yearly inflation while active
Requires Wealth of Nations.png or Common Sense.png DLCs
Scutage.png Pay Off Debts Yes Yes Subject has Debts to pay off Liberty desire.png-5% Liberty Desire per loan paid Requires Rights of Man.png DLC

Enhance provinces of subject nations[edit]

It is possible for the overlord to construct buildings in the provinces of subjects, and to develop them to reduce their liberty desire, the more points are spent on the development, the less liberty-desirous the subject will be. However, base liberty desire increases with each point of development, so this is a short-term savings that may hurt you in the long run.

Military focus[edit]

A nation can set it's subject's military focus to either of the 6, this will determine how they behave in wars ( NB: The subject will not obey you or leave their country's borders at war if it has more than 50% liberty desire:

Focus Behaviour
No focus The subject will decide its own strategies.
Supportive The subject will seek to attach to friendly armies.
Aggressive The subject will be aggressive towards enemies.
Passive This will make the subject stay with armies in their own territory, and defend there.
Defensive This will make the subject defend the allie's territory. ( Recommended for stronger subjects )
Siege This will make the subject use it's armies to siege down hostile fortresses and not seek any battles.
Subject nations Client stateColonial nationMarchPersonal unionProtectorateTrade companyVassal
Other EnvoyAllianceRelationsDiplomatic feedbackEspionageColonizationPapacyHoly Roman Empire