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A vassal is a semi-independent nation that owes allegiance to a suzerain country, often much more powerful than the vassal. The vassal offers regular financial tribute and military assistance, and in return receives protection.

Creating a vassal

There are several different ways to vassalize a nation. Countries can become vassals in the terms of a Peace Treaty, annexed diplomatically, or upon receiving autonomy from a larger country, either as a normal nation or as a Client state. The Emperor can also vassalize members of the Holy Roman Empire by passing the penultimate Imperial Reform.

It is not possible to create a vassal if the differences in tech group is too big: a difference in technology cost of 50% or larger will require the relation to be a protectorate rather than a vassal, unless the target is in the Nomad tech group; e.g. it is possible for a Western nation (100%) to vassalize Eastern (120%), Ottoman (125%), Muslim (140%) groups as well as other Western nations, but not Indian (150%) and lower groups. Since this is relative, Eastern nations can vassalize Indian, Chinese and Sub-Saharan (160%), but not Mesoamerican (250%) and below.

Subject Interaction

As of 1.12, it is now possible to interact with a vassal. This is done through the Subject Interaction section of the Subject Menu.

  1. Placate Local Rulers: Placates the local rulers, changing their Liberty Desire by +10% at the cost of -20 Prestige.
  2. Enable Embargo Rivals: This will cause your subjects to embargo your rivals at the cost of -5% Liberty Desire
  3. Place Relative on the Throne: You will place your own dynasty on their throne. Changes Liberty Desire by +10%. Subject must have a regency.
  4. Enforce Religion: Forces them to change their religion to yours, changing liberty desire by +50%.
  5. Enable Scutage: Forces your vassals to pay an additional +50% of their income to you as scutage, but they will no longer be called to wars. Disabling scutage is possible, but increases Liberty Desire by 10%.

Release a nation

To release a nation whose lands you control you must be at peace. This is something you may want to do if, for example, you gain provinces in a peace that you can't core or sell. The method of releasing a nation is as follows:

  1. Bring up the Diplomacy menu.
  2. Ensure that the menu displays information for your country. In the bottom right hand corner of the menu click on View Own Country if the player's country is not shown.
  3. In the bottom right hand corner of the menu that pops up, you will see the button called Create Vassals.
  4. If the button is gray and not clickable then you either have no nations to release or you are at war.
  5. Click the Create Vassals button and choose the nation you wish to release as your vassal. Nations are eligible for release when the following conditions are satisfied
    • Target nation does not currently exist
    • You control provinces that have the target nation's cores and primary culture

The released vassal will take the master country's religion, but only if the religion in the vassal's capital is of a different religious group. A same-religious-group capital will release as a vassal with its own capital's religion. The vassal may convert some provinces using its missionaries, leaving the suzerain's missionaries free.

Its tech group will be whatever that country had when it existed, although its initial tech levels will match its master, e.g. Creek will always release as New World Tech Group, Creek culture, its master's religion and its master's tech levels.

If the released nation's core provinces include the releasing country's capital, the capital will not be released, even if it is in the list of provinces to be released.

Since patch 1.2, when releasing a nation into vassalage, you may now switch to playing as that vassal. As of patch 1.9 this feature also works in ironman mode, though it will disable most Achievements.

Kingdom of Jerusalem

A special case for releasing a country as a vassal is the Kingdom of Jerusalem, that can be released as a vassal through a decision by any Catholic ruler, except by The Knights or Cyprus who will instead remain in the control of the Kingdom. The releasing nation gains +25 prestige Prestige.png, and Jerusalem inherits the culture of the releasing nation.

Create client state

A country with at least diplomatic technology 22 can create Client states. They function identically to other vassals, but their provinces, government form, name, color and coat-of-arms can be customized by the player. They also have slightly less Liberty Desire than other vassals, and an unique group of Ideas shared by all client states. A country can have a maximum of 10 client states.

Force vassalization (military)

In order to force vassalize a nation, you need to be at war with them. In the negotiations screen, you can find the option under the menu 'treaties' which should be the farthest right menu button on the screen. When force vassalizing someone, the warscore needed is determined by the base tax of all their provinces. Sometimes, the base tax is too high to vassalize the target nation. Typically, a nation of 5-6 provinces or fewer can be vassalized. In some instances it can be cheaper to take some provinces and vassalize the rest if the cost of vassalizing the whole country is too great.

Generally only countries of 4 or fewer provinces, or poorer provinces, can be vassalized via war. The maximum war score is 100% and a rich province typically costs about 25% war score. A good way to reduce a country's size is to force them to return cores and release countries, as these do not result in overextension or Aggressive Expansion for the annexing country. However, pagan countries can be annexed when fully occupied regardless of war score.

The benefits to the military victor of choosing vassalization instead of annexation are:

  • No Overextension penalty.
  • Using diplomatic points instead of administrative points to annex vassalized provinces.
  • The ability to feed a vassal, to conquer land without using one's own admin power, as well as to expand whilst having a lot of overextension.

The downsides to the military victor of choosing vassalization instead of annexation are:

  • The vassal occupies a diplomatic relation slot, reducing the number of allies possible (but vassals are more dependable than allies).
  • The direct benefits of those provinces to the overlord are smaller than if they belonged to the overlord (less tax, production, forcelimits, trade power, and the overlord can't build buildings). (However, the overlord and vassal combined are stronger than either one alone.)
  • Longer time until the land is part of the victor's country. There is a waiting period of 10 years in addition to the time that it takes to diplo-annex the vassal.
  • Once annexed the Local Autonomy of every province will be raised to 75%, instead of 50% if taken in war without a claim
  • Once annexed, the country gains a -3 malus to its diplomatic reputation. This matters in regards to being elected as the emperor, diplo-vassalizing countries and diplo-annexing ones, as well as a host of other diplomatic actions. Without help from advisors, ideas, or events, annexing another vassal will be very slow or impossible until this malus expires.

Offer vassalization (diplomatic)

In order to offer vassalization to a nation, you must meet these requirements:

  • Have a military alliance with the target nation.
  • Have a relation of 190+.
  • The target country must be at peace.

Other factors such as your diplomatic reputation, relative size of military and relative base tax also come into play:

File:Eu4 Vassalization Table.PNG
Table of base tax modifiers for diplomatic vassalization
  • +20 to -20 from trust/distrust
  • +30 to -90 from base tax. Determined by 60*(your base tax)/(target's base tax)^2 - 90, where base tax is the total province base tax of the country without any buildings or modifiers. In addition the base tax of your vassals, along with tax income modifiers, add to the base tax of your own nation as well.
  • +20 to -40 from relative size of military
  • +10 Friendly or Threatened attitude
  • +10 per difference in Government Rank
  • +10 Having a royal marriage
  • +3 per point of Diplomatic Reputation (Rounded down to nearest whole number)
  • -1000 if not a strategic interest
  • -1000 has more than 100 development
  • -1000 has vassals of their own
  • -1000 Elector of Holy Roman Empire
  • -1000 the Papal State
  • -100 Hostile or Outraged attitude
  • -30 Member of Holy Roman Empire for foreigners
  • -20 Member of Holy Roman Empire for another member
  • -20 if not same religious group
  • -20 Neutral attitude
  • -30 if either country is a Merchant Republic
  • -0.5 per distance
  • [Other factors?]

Hover over the cross or check-mark in the "offer vassalization" button to see whether they would accept an offer or not.

Benefits of vassals

Vassals are essentially puppets of their suzerain, or overlord country. They cannot declare war or enter royal marriages, except with their overlord. They always join their suzerain's wars, and cannot negotiate separate peace treaties. They give 10% of their tax to the suzerain, increased by +25% by the feudal and elective monarchy and archduchy governments, by +33% by the iqta government and following other modifiers:

Income from vassals.png Traditions Ideas Bonuses Policies
  • Offensive-Administration: Vassal Taxation Policy
  • Kanem Bornuan traditions
  • Mesoamerican traditions
  • Influence idea 1: Tribute System
  • Ashikaga idea 7: Reform the Shogun - Shogu System
  • Bosnian idea 5: Land of Princes
  • Herzegovinian idea 5: Land of Princes
  • Ayutthayan ambition
  • Goslar ambition
  • Influence-Economic: Vassal Obligations Act
  • Influence-Expansion: Overseas Dominions
  • Influence-Quality: The Integrated Administration Act
  • Lusatian traditions
  • Malian idea 1: Restore Malian Suzerainty
  • Lunda ambition
  • Zambezi ambition

Vassals increase the suzerain's land force limitby how much?, but not naval force limit. This contribution can be increased by 50% with the 7th Influence idea. The suzerain also receives military access and the ability to dock its boats in the vassal's ports, but not fleet basing rights. If the vassal is an elector in the Holy Roman Empire, its suzerain gets a +50 point bonus to the vassal's electoral vote opinion and a -50 point malus (stacking for each vassal) to the opinions of non-controlled electors.

Vassals may try to break free by declaring war on their overlord. They may also ask other nations to support their independence. Nations supporting independence are automatically called into the independence war, and act as temporary allies for the duration of the war. Other countries may offer support for independence without being asked, although vassals that like their overlord will never accept.

After ten years vassals can be annexed by their suzerain, which gets cores on all provinces that the vassal considers cores. This makes vassalization a good way to expand without spending administrative points, or in some cases even without having to wage war.


With the Art of War.png Art of War DLC a suzerain can also change a vassal into a March icon.png march. A march doesn’t pay taxes to his overlord, it is un-annexable, has -25% Liberty Desire and has the following bonuses:

  • National manpower modifier.png +25% National manpower modifier
  • Land force limit modifier.png +30% Land force limit modifier
  • Naval force limit modifier.png +30% Naval force limit modifier
  • Fort defense.png +20% Fort defense
  • Manpower recovery speed.png +20% Manpower recovery speed

The status of a march can be revoked for the price of Icon stability.png −1 stability and Icon diplomacy relations.png −200 relations. As of 1.12, a march can go above the 60 base tax limit and stay as a march.

Liberty desire

Main article: Subject nation#Liberty desire

Since patch 1.10 (El Dorado), vassals (including Marches) have a liberty desire similar to that of a colonial nation, except unaffected by tariffs. Like colonial nations, vassals with a liberty desire less than 50% will remain in the 'Loyal' attitude, while vassals with a liberty desire above 50% will become 'Disloyal'.

Disloyal vassals may:

  • Refuse to send troops to a war waged by the liege.
  • Seek independence support and accept independence support from other countries.
  • Forge alliances with other disloyal vassals.
  • Declare a war of independence (which they will once they believe they have a chance based on the relative military powers of them and their allies versus their liege).

Many factors affect liberty desire, including relative military strength, relations, and trust.

Because vassals taken from wars have poor opinions and distrust of their new liege, it is important to raise the vassal's opinion as much as possible before the truce from the war expires. When suing for peace, increasing the warscore cost of the demands will also increase the truce period, granting more time to improve vassal's opinions, build trust through wars, and allow bad opinion modifiers to decay.


A vassal that has at least one province within coring range of its suzerain can potentially be annexed as the result of a diplomatic action. After 10 years and if the vassal has +190 relations with the suzerain, the suzerain can take the diplomatic action Annex Vassal to start the process of incorporating the vassal's provinces into the suzerain country. The original date on which the vassal was acquired can be found in the diplomacy tab of the vassal on the tooltip for the vassalage icon Vassalage.png. Once annexation begins, relations may drop without any effect.

Annexing occupies a diplomat until complete. The base cost of annexing a vassal is 8 diplo points per development multiplied by hostile core creation modifiers, spent at a rate determined by

  • +1 base
  • +1 if same culture as suzerain
  • +1 if same religion as suzerain
  • + or - suzerain's diplomatic reputation (rounded down; rounded 1.11.4).

If the total is 0 or negative, annexing will pause, but not go backwards. When all the diplo points are spent, annexation finishes and the suzerain will see the following effects:

  • "Annexed Vassals" national modifier for 10 years giving -3 Diplomatic reputation.png diplomatic reputation.
  • Relations with other vassals -30. Stacks. Does not apply to marches.
  • Relations with other HRE members -25, if the vassal was in the Holy Roman Empire.
  • Control of all the vassal's provinces, army, and navy. This may put the suzerain well over its force limit.
  • Cores on all the provinces that the vassal had cores on.
  • All of the former vassal's provinces not a core of the suzerain before integration will have 75% Local autonomy.png local autonomy (or their previous autonomy level, if above 75%).

Diplomatic annexation strategy

Due to the administrative point cost and time of coring conquered provinces, especially for large countries, diplomatic annexation is an interesting alternative to conquer large swathes of the world: when a vassal is annexed, all of the vassal's core provinces become cores of the annexing country. Annexation also doesn't incur aggressive expansion relations penalties.


  • Better Relations Over Time is the most important bonus, as it makes Aggressive Expansion decay faster. Hiring a Diplomat increases this modifier.
  • Static modifiers include:
    • Royal Marriage +25
    • Alliance +50
    • Enemy of my Enemy (have the same rival as them) stacking 1/year up to +20
    • Same religion +10
    • Guarantee by promising to defend against aggressors +10
    • Military Access by giving target nation military access +10
    • Imperial Grace +40 (the emperor of the Holy Roman Empire can spend imperial authority to increase relations with a country).
  • Decaying modifiers include:
    • Gift by giving money to the target country +1 up to +25 (60 months)
    • Honored Alliance by responding to a request for military aid +10 (decays/year)
    • Fought to the End by not negotiating a separate peace in an alliance war +20 (decays/year).
    • Defending the vassal territory from an army +10 (decays/year)
    • Liberating vassal territory from an occupation +25 (decays/year). Both defending and liberating provinces work against rebels.
    • Giving war subsidies, up to +15. Once cancelled, relations boon is gone.

Choosing a vassal

A good candidate for diplomatic annexation has the following:

  • Lots of cores: this makes feeding the vassal easier.
  • Lots of unowned cores or claims: wage war with other nations and force them to return cores to your vassal in a peace deal.
  • Small province base tax: a vassal must be economically much smaller before it can be diplomatically annexed.
  • Not a merchant republic; they have a malus for accepting vassalization.
  • No Hostile core creation modifier
  • The same religion and different culture than their overlord. They can convert lands for you, and they will use their land more efficiently if they're the culture of what you will conquer.

Feeding a vassal

It is sometimes advantageous to transfer provinces to a vassal. This is called "feeding" the vassal. Because each vassal takes up a diplomatic relations slot, as well as a Diplomat during the actual annexation process, it can be a good idea to "feed" vassals provinces rather than take on additional vassals, however, the more provinces the vassal has, and the more base tax they generate, the longer will the annexation process take.

Returning cores

The suzerain can give provinces to a vassal by forcing a defeated country to return the vassal's cores in a peace deal. This is less expensive in terms of Aggressive Expansion than taking provinces directly, but still costs the same diplomatic monarch points. Since these provinces are the vassal's cores, they will not overextend the vassal. Returning provinces gives a large boost to the receiving country's opinion of the military victor (+40 per province up to 200 total, decay at 1 per year).

Alternatively, a vassal may independently occupy an enemy province where it has a core. A province sieged by a vassal will be occupied by their suzerain, but an exception is when the vassal has a core in the province and is the siege leader. The suzerain can also transfer occupation to their vassal whenever needed.

Once a province is occupied by the vassal, the suzerain war leader can demand the enemy to directly cede the province to the vassal. If this happens, the vassal will use their own diplomatic monarch points though their overlord will still take the Aggressive Expansion for the province. This also gives an opinion boost, but less than returning a core with the suzerain's diplomatic monarch points.

Selling provinces

Selling provinces will not work if you've already started the annexation process. Countries who are already Vassals will only buy provinces that are either cores, claims, an accepted culture or formerly owned territory of the vassal. The province history button can confirm if a territory is formerly owned if there is no longer a claim/core there. Also the province you want to give away needs to be in your coring range (which is the case with any province that is either adjacent to a core of yours or in the official range of one of your cores or your subjects' cores).

It is much easier to sell provinces to countries that aren't yet your vassal, however care must be taken to make sure that after selling the province the country doesn't become ineligible to become a vassal (either diplomatically or militarily due to tax base).