A vassal is a semi-independent nation that owes allegiance to a country. 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 be force vassalized in a Peace Treaty or can agree to vassalization via a diplomatic offer. They can also receive autonomy from a larger country, either as a normal nation or as a client state. The Holy Roman Emperor can also vassalize members of the Holy Roman Empire by passing the penultimate Imperial Reform, "Revoke The Privilegia".
Releasing a nation
A nation at peace may release another nation whose lands it controls. This can help after gaining provinces in a peace deal that can't be cored or sold, drive overextension too high, or are extremely rebellious. One can also release a vassal in order to reconquer its core provinces in future wars for less aggressive expansion and no administrative power cost for either country. The method of releasing a nation is as follows:
- Bring up the Diplomacy menu. If the player's country is not shown, click on View Own Country in the bottom right of the menu.
- In the bottom right hand corner of the menu that pops up, there is a button called Create Vassals.
- If the button is gray and not clickable then either there are no nations to release or the player is at war.
- Click the Create Vassals button and choose the nation to release as a vassal. Nations are eligible for release when the following conditions are satisfied:
- The country is at peace
- Target nation does not currently exist
- Releasing nation owns and controls provinces that have the target nation's cores and a culture in the same group as their primary culture.
For example, Iraq has a core on Hisn Kayfa. However, this province's culture is Kurdish, which is in the Iranian culture group; Iraq's historical culture is Mashriqi, which is in the Levantine culture group. As such, it is not possible to release Iraq from Hisn Kayfa. You'll have to conquer a province with both an Iraqi core and a Levantine culture.
Whatever religion is the largest in all of the new vassal's cores everywhere in the world (even if currently not owned by the nation) in terms of development will become the vassal's state religion (cores belonging to its original religion apparently count double); the number of provinces following any given religion is not the determining factor. If a same-religion vassal is necessary, converting the future vassal's richer provinces before releasing the vassal will ensure the vassal's adherence to the true faith.
The new country will maintain its default assigned tech group but will start with all the technologies its master possesses. The Creek, for example, will always release as North American tech group country with Creek culture equal to its master in technology.
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.
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, Provence or Cyprus who will instead remain in the control and switch to the Jerusalem tag. The releasing nation gains +25 prestige, and Jerusalem inherits the culture of the releasing nation.
Create a march
- Main article: March
A suzerain can also change a vassal (including a client state) into a march, which is a special militaristic kind of vassal. Marches gain bonuses to their military power but cannot be diplomatically annexed and do not pay taxes to their overlord. The overlord can revoke march status but will suffer a -1 stability hit and a -50 penalty to relations with the former march. As long as the march's development is less than 25% of its overlord's, it receives the following bonuses:
Please help with verifying or updating this section. It was last verified for version 1.33.
|+25%||National manpower modifier|
|+30%||Land force limit modifier|
|+30%||Naval force limit modifier|
|+20%||Manpower recovery speed|
|−20%||Land maintenance modifier|
|−20%||Naval maintenance modifier|
Force vassalization (military)
A nation can be forcibly vassalized as part of a peace treaty (option in the Treaties menu of the negotiation screen). The total warscore cost for force vassalization is 1 warscore per 1 development plus 5 warscore for each province (plus roughly 25% of the capital province development, plus a value for local trade power), so you can only vassalize countries with typically at most 70 development and 3 to 4 provinces without cost reductions via absolutism or the rare Subjugation casus belli (available through some missions and events). To see the target cost select a province and hover your mouse over the "Province War Score Cost", a crossed shield and star icon, it will also show you the total force vassalization cost.
The benefits to the military victor of choosing vassalization instead of annexation are:
- No Overextension penalty or separatist unrest (usually +15, decaying by only 0.5 per year).
- Using diplomatic points instead of administrative points to annex vassalized provinces.
- The ability to feed a vassal provinces in peace deals, gaining land without using one's own administrative power or becoming overextended. This is especially useful for countries that have many foreign cores, as conquering them on the vassal's behalf incurs less aggressive expansion, costs less manpower with the reconquest CB, and results in no separatist unrest or autonomy.
- Aggressive expansion penalty reduced by a third.
- The vassal will manage its own armies in war, which is less micromanagement for a player ruling a massive empire.
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).
- Little monetary benefit to the overlord. However, if a vassal has provinces in states, is paying a high vassal tax and possibly transferring trade power, the difference to owning the provinces yourself as mere territories is not huge.
- Longer time until the land is part of the victor's country. There is a waiting period of ten years in addition to the time that it takes to diplomatically annex the vassal.
- Once annexed, the Local Autonomy of every province will be raised to 60%, instead of 50% if taken in war without a claim.
- Once annexed, the country gains a −3 malus to its diplomatic reputation for ten years. This matters in regards to being elected as the Holy Roman Emperor, diplo-vassalizing and diplo-annexing countries, and many other diplomatic actions as well. Without help from advisors, ideas, or events, annexing another vassal will be very slow or impossible until this malus expires, so you should ideally time multiple annexations to complete at once.
Newly force-vassalized countries will receive a −100 opinion malus to relations with their overlord, which will decay at a rate of 2 per year. It is often a good idea to immediately begin improving relations with the new vassal to prevent disloyalty. The vassal cannot seek support for independence until the truce expires.
Be careful if the country you are vassalizing is currently involved in a different war: In all other wars in which they are the war leader, whether on the attacking or the defending side, you will take their place! (If they are merely involved as an ally, they will sign an automatic white peace instead.) If your potential new vassal is leading the attack or defense in a difficult war, or leading a war against an ally of yours, you should probably wait for peace or just annex whatever you can directly.
However, you can also use this mechanism to your benefit: Vassalize a small neighbor while they are also defending against a large neighbor, and, most likely, you will be able to call AI allies to support you, while the AI attacker will be unable to do so. This is a good strategy when playing small-to-medium-sized nations with dangerous neighbors, e.g. Novgorod vs. Muscovy vassalizing Tver or Byzantium vs. Ottomans vassalizing Albania.
Offer vassalization (diplomatic)
The requirements for offering diplomatic vassalization are as follows:
- Must have at least +190 relations with the target country.
- Must be allied to the target country.
- Target country must be at peace.
- The difference in technology cost between the vassalizer and the target country must be less than 50% After patch 18 the difference shouldn’t be higher than 1 accepted institution.
- Target country must have at most 100 development
- Must not own cores of the target country.
Willingness to accept vassalization is shown in the tooltip for the check-mark in the "offer vassalization" button.
The factors that influence an AI nation's desire to accept a vassalization offer are:
|Attitude towards proposer||Ally: +10|
|We have a royal marriage||+10|
|Trust||Scales linearly between the following points:|
|+10 at 100 trust|
|0 at 50 trust|
|−40 at 30 trust|
|−2000 at <30 trust|
|Proposer's diplomatic reputation||+3 per positive point|
|−3 per negative point|
|Difference in government rank||+10 for each higher rank|
|−30 for each lower rank|
|Nation's government rank||kingdom: −10|
|Nation has a religion not in the same religious group||−20|
|Nation has a different religion within the same religious group||−10|
|Nation is a merchant republic||−30|
|Proposer economic base compared to target nation||+30 to −90[diplomatic vassalization 1]|
|Proposer military power compared to target nation||+20 to −40|
|Proposer is a merchant republic||−10|
|Nation is member of the empire||−25 if proposer is also a member|
|−75 if proposer is not a member|
|Nation is an elector||−1000|
|Nation has subjects of their own||−1000|
|Nation is The Papal State/the Pope||−1000|
|Nation has more than 100 total development||−1000|
|Nation is not a strategic interest||−1000|
|Proposer owns target nation's core provinces||−1000|
|Distance between borders||−0.5 per distance between borders[diplomatic vassalization 2]|
|Austria mission: Shift the Balance||+25 for 30 years|
|Savoy mission: Push on Tuscany||+30 for 30 years|
|Songhai mission: Protect our Legacy||+15 for 25 years|
- Determined by:
The minimum value is −90 and the maximum +30. Only vassals(and daimyos) matter for the formula. The development of marches, junior partners, colonial nations and tributaries is not taken into account. The autonomy modified development of the players country is displayed in the tooltip of the presence bar of an institution in the technology tab. Reworking the formula it be be simpler to use this formula to determine "the proposer's required size = 3*((target's dev+10)/2)^2"
- Distance between borders can only be seen in debug mode.
- Through a peace deal: when suzerain loses a war.
- Through diplomacy: a suzerain can choose to release its vassal for a cost of -25 prestige and -200 vassal's opinion modifier. However, if the vassal has over 50% liberty desire, the relation penalty won't happen.
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.
The suzerain also receives military access and the ability to dock its fleets 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, being complete countries in their own right, have their own armies, navies, manpower, and envoys. The armed forces of a vassal and overlord are stronger than the overlord's would be alone if those provinces were annexed, and often the vassal's religious and cultural tolerance enables them to exploit their land more efficiently than the overlord could. The additional missionaries can make religious conversion faster, and their merchants can help steer trade in the correct direction.
Vassals may try to break free by declaring war on their overlord. With DLC, 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.
Income from vassals
Vassals have to pay a part of their tax income to the suzerain. This part is determined by the ‘vassals tax efficiency’ of the overlord, which is the sum of all ‘income from vassals’ modifiers. The base value for the all countries is 10%. A overlord can increase its Income from vassals modifier by the following:
|+25%||as elective monarchy or feudal monarchy|
|+10/20/30%||as tribal kingdom (depending on government rank)|
|+10/20%||holding Versailles while culture in province is in French group and accepted by owner (only with )|
|+10%||holding Alhambra while religion in province is in either Christian or Muslim group and same as owner (only with )|
|+5%||with parliament and “Harmonization of State Laws” or “Create Offices for Vassal Nobles” as active issue|
|–5 - +5%||depending on legitimacy (0-100)|
Ideas and policies:
|+25%||Firm Hand||Influence ideas event: “A Firm Hand”||for 10 years.|
|+10%||Vassals Feel Safe||Influence ideas event: “Vassals Feel Safe”||for 10 years.|
|−5%||Vassals are unwilling to pay scutage||Subject interaction events: “War Never Changes”||for 5 years.|
|+50%||If Scutage is enabled for that vassal in Subject Interactions|
Vassal force limit contribution
Vassals increase the suzerain's land force limit by 1 and additionally 10% of the vassal's force limit and marches by 1 and additionally 20% of the march's force limit, but not the suzerain's naval force limit. This contribution can be increased by the following.
Ideas and policies:
Decisions and events:
|+100%||Firm Hand||Influence ideas event: “A Firm Hand”||for 10 years.|
- Main article: Subject nation#Liberty desire
Vassals have liberty desire (introduced with patch 1.10) like the other subject nations. A liberty desire less than 50% will remain in the 'loyal' attitude, while vassals with a liberty desire above 50% will become 'disloyal'.
Nations who are historical rivals will have a base liberty desire of 50% and as such make poor vassals since to diplo-annex them there needs to be less than 50% liberty desire.
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 subjects.
- 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).
- Prevent their own annexation, or pause it if annexation has started.
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.
- Main article: Subject_nation#Subject_interactions
Interactions with vassals are done through the Subject Interaction section of the Subject Menu.
A vassal or client state can be diplomatically annexed by its overlord through the Annex vassal option. Annexation occupies a diplomat until complete, and results in direct control of the former subject's territory and military.
The requirements for initiating diplomatic annexation are:
- The subject's vassalage has lasted at least 10 years. The vassalization date can be found in the vassal's diplomacy screen on the tooltip for the vassalage icon .
- Vassal opinion of overlord is at least 190.
- Liberty desire is less than 50%.
- Vassal is at peace.
- Vassal has control of its capital.
- Vassal has at least one core province that can be cored.
Annexation progress of vassals appears in the diplomacy interface as a horizontal progress bar next to the vassalage icon . If the annexation process is cancelled before completion, all progress is lost, including the invested diplomatic power.
Diplomatic annexation will be paused if:
- the vassal's liberty desire is greater than 50%;
- the vassal does not have control of its capital; or
- the vassal is at war and any of its provinces are occupied by rebels or an enemy nation.
The full formula for diplomatic annexation cost is:
The cost reduction from administrative efficiency is capped at 90% and the final cost per province can not go below 0.1 dip points per development(or 1.25% of the normal cost). The final cost for the whole country is rounded, so it can be 0 in extreme cases.
The base annexation cost is 8 diplomatic power per development of the vassal, excluding any provinces the overlord has cores on. The cost in diplomatic power is increased by the local coring cost modifier which refers to the hostile core-creation cost of the vassal. Having claims or permanent claims on some provinces of the vassal does not change the integration cost. This cost is decreased by administrative efficiency, all power cost modifiers and diplomatic annexation cost modifiers. These modifiers are displayed below:
|permanent modifier “King of Kings” from the Provence mission King of Kings||−20%|
|with parliament and “Harmonization of State Laws” or “Create Offices for Vassal Nobles” as active issue||−15%|
|permanent modifier “Bohemian Commonwealth” from the Bohemia mission Bohemian Commonwealth||−15%|
|permanent modifier “Lord of Austria” from the Hungary mission The Duchy of Austria||−10%|
|Papal Legate modifier for 20 years||−10%|
|permanent modifier “Unity of Italy” from the mission “Union with Naples” which is available for Savoy and Sardinia-Piedmont||−10%|
|with noble privilege Nobility Integration Policy||−5%|
Speed of annexation
The overlord invests diplomatic power into the annexation process each month at the following rate:
- +2 base rate
- +1 if same religion
- +1 if in same culture group
- ±1 per positive/negative point of diplomatic reputation.
If the total balance of diplomatic power is 0 or negative (hence the balance cannot cover the monthly rate), annexation will pause, but not reverse
Note that if acquiring multiple subjects concurrently, this monthly rate as above will apply to each subject independently (modified for the culture and religion of each), even if it results in a monthly deficit; as long as there is still a positive diplomatic power balance to cover the monthly deficits as per the rule above. If not, progress will pause.
Annexation is completed once the required diplomatic monarch points are spent, and results in the following effects:
- +5 prestige.
- An event gives the "Annexed Vassals" national modifier for 10 years giving −3 diplomatic reputation. (While the penalty does not stack, the duration of the penalty does so annexing 3 vassals will result in a 30 years penalty). You can avoid getting this penalty by granting a particular estate privilege to your countries version of the nobility.
- −30 relations with other vassals. Does not apply to marches. Will vanish completely after 20 years if no new stacks are added, regardless of current amount. (Stacks. -200 limit)
- −25 relations with other HRE members, if the vassal was in the Holy Roman Empire. (Stacks)
- Control of all the vassal's provinces, army, and navy. This may put the overlord over its force limit.
- Cores on all the vassal's core provinces.
- 60% local autonomy in all new cores (or their previous autonomy level, if above), and 0 if the overlord already had a core.
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 and no separatism is incurred if Separatist Rebels have not taken control of any provinces since the initial annexation. The diplomatic power is also expended over time and there is no penalty akin to overextension for taking a long time while annexing.
- Improve Relations is the most important bonus, as it makes Aggressive Expansion decay faster. Hiring a Diplomat advisor 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
- Transfer Trade Power by asking target nation to transfer trade power to your nation +10
- Imperial Grace +40 (the emperor of the Holy Roman Empire can spend imperial authority to increase relations with a country).
- Great Power influence: +25 as long as influence is active (10 years unless renewed)
- 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 unowned cores or claims: wage war with other nations and take the provinces cored or claimed by the vassal so they can core the land instead of you. The "Grant Province" option should be used from 1.14 onwards, as it reduces the liberty desire of the vassal by half of the total development granted, easily keeping it in line, provided granting the province does not increase your subject's total development over 100.
- Strong military ideas or economic ideas - large vassals can contribute 20,000+ men to wars, sieging down forts on a different front, cleaning up unfortified provinces that haven't been occupied and sometimes even winning battles on their own.
- Not a merchant republic; they have a malus for accepting vassalization.
- No Hostile core creation modifier - these are applied to all cored provinces, including newly cored ones "fed" to the vassal, making those provinces even more expensive to annex than they normally would have been. In particular, North African and Caucasian nations tend to have these modifiers in their traditions.
- Ability to deal with unrest without overlord army help. While you can keep your armies around to patrol for rebels in vassal lands, it is better to look for a vassal that has unrest reduction, tolerance or missionary strength in its National Idea set. Ideally the vassal will be the same religion as the overlord but it is not necessary.
- Same culture/religion as overlord - each will increase the diplomatic power per month spent on annexation. If Diplomatic Reputation is low then this can make a huge difference in annexation speed.
- National Ideas which increase a vassal's force limit in turn increase your own force limit due to the percentage for the vassal's force limit being added to your own. Likewise, vassals which take Offensive and Quantity ideas further increase this.
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 - each vassal annexed also makes it more difficult to annex subsequent vassals with a stacking -30 hit to relations that can make it impossible to get older vassals above 190 relations along with a -3 penalty to diplomatic reputation for 10 years, reducing the speed at which vassals can be annexed in that time. However, the more provinces the vassal has, the higher its overall development, increasing the diplomatic power required to annex it. Large vassals can take thousands of diplomatic power and decades to annex, even with discounts from Influence ideas and Administrative efficiency. It is recommended to try and only annex vassals when taking Influence ideas as the cost will be 25% less; for a bigger discount, adopt the Vassal-Integration Act policy (requires Administrative Ideas completed in addition to Influence Ideas).
The best way to feed a vassal is to annex territory directly and grant the provinces to the vassal through the subject interaction menu (requires Common Sense). This will reduce the vassal's liberty desire by half of the total development granted to it, temporarily offsetting the increase in liberty desire that vassals get from becoming more powerful and gaining more development - feeding a vassal even 200 development worth of land will reduce its liberty desire by 100%(but increase it again by 50% because of the increased development). Vassals will not accept a province if it will increase their Overextension to 100% or more, and by annexing the land directly the overlord might have to suffer more Aggressive Expansion and pay diplomatic power for the provinces, if the provinces being taken were not included in the war goal.
The advantages of vassal feeding are primarily in not having to deal with rebels as much (as the AI will often use its military power for Harsh Treatment, saving you the expense) and saving Administrative Power in favour of expending Diplomatic Power; Administrative Technology is almost always more important than Diplomatic Technology as it allows you to unlock new idea groups. From patch 1.16, care must be taken to balance vassal feeding with direct expansion as falling too far behind in diplomatic tech relative to administrative and military tech will increase corruption.
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.
Beware that the Administrative Efficiency used to compute the province war score cost is the one of the country who receives it. If you have a better Administrative Efficiency than your vassal, you will have to pay more war score cost to give him directly those provinces (via "Cede province" or "Return core") than taking them for you directly and ceding them to the vassal in peacetime (via the option in the Subject Interaction menu (available with the Common Sense DLC)). But as previously mentioned, the first option will give less Aggressive Expansion, and give an opinion bonus, whereas the second one will give more AE and also a reduction in Liberty Desire for the concerned subject (more than you get from the opinion boost in the first option), which stacks (contrary to opinion, capped at 200).
Selling provinces will not work if the annexation process has been started. 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 to be sold needs to be within coring range.
It is much easier to sell provinces to countries that aren't yet vassalised, 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).
Annexing the vassal
Since the cost of annexation can change during annexation, it may be worth only buying modifiers once the full annexation cost (post-modifier) has nearly been paid, especially if the modifier is a policy (i.e. the cost is increased for every month over 10 years for which it is active).
Consider timing annexations so that they finish within four months of one another: since an event such as that giving the Annexed Vassals modifier can be postponed for up to four months, the player can, for this time, avoid the hit to diplomatic reputation, and can annex vassals at full speed without waiting 10 years between annexations. Since the −3 diplomatic reputation from the Annexed Vassals modifier does not stack, you will avoid long periods with the penalty.