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# 附庸国

（重定向自Diplomatic annexation

A vassal is a semi-independent nation that owes allegiance to a 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 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. The method of releasing a nation is as follows:

1. 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.
2. In the bottom right hand corner of the menu that pops up, there is a button called Create Vassals.
3. If the button is gray and not clickable then either there are no nations to release or the player is at war.
4. 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:
• Target nation does not currently exist
• Releasing nation controls provinces that have the target nation's cores and a culture in the same group as their primary culture.

Whatever religion is the largest in the new vassal's territories in terms of development will become the vassal's state religion; 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.

When releasing a nation into vassalage, the player may switch to playing as that vassal. When done in ironman mode, this will disable most achievements.

#### Kingdom of Jerusalem

A special case for releasing a country as a vassal is the Kingdom of  耶路撒冷, 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 and switch to the Jerusalem tag. The releasing nation gains +25 prestige, and Jerusalem inherits the culture of the releasing nation.

### Create a 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:

 +25% 全局人力修正 +30% 陆军上限修正 +30% 海军上限修正 +20% 防御效率 −20% 堡垒维护费 +20% 人力恢复速度

### Force vassalization (military)

A nation can be force vassalized as part of a peace treaty. In the negotiations screen, there is an option for "Become Vassal" under the menu "Treaties" which should be the farthest right menu button on the screen. When force vassalizing a nation, the warscore needed is determined by the total development of all their provinces. The base warscore cost per point of development is 1.[1] Sometimes, the total development is too high to vassalize the target nation. The normal maximum is a total development of 100. However, certain missions/cb's can lower the warscore cost by a % (example: Subjugation reduces cost by 50%, and cuts out any diplomatic power costs).

In the early game, only low-development countries with poor or few 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, and if the nation is of a Buddhist faith, it does not pay diplomatic power.

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.
• Less agressive expansion than simply conquering the provinces of the country.
• 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).
• 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 60%, 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 and diplo-annexing countries, and a host of 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.

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.

### Offer vassalization (diplomatic)

The requirements for offering diplomatic vassalization are as follows:

1. Must have at least +190 relations with the target country.
2. Must be allied to the target country.
3. Target country must be at peace.
4. The difference in technology cost between the vassalizer and the target country must be less than 50% After patch 18 the difference shouldnt be higher then 1 accepted institution.
5. Target country must have at most 100 development
6. 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:

Factor Effect
Attitude towards proposer Ally: +10
Friendly: +10
Threatened: +10
Neutral: -20
Hostile: -100
Outraged: -100
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 per difference in rank
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
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  教宗国/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

†: Distance between borders can only be seen in debug mode.

‡: Determined by:

 ${\displaystyle {\text{relative economic base}}=60\,\cdot \,{\frac {{\text{base tax}}+{\text{base production}}+{\text{current vassal base tax}}}{({\text{target base tax}}+{\text{target base production}}+{\text{target base manpower}})^{2}}}\,-\,90}$

Where base tax and production are the total province base tax and production of the country without any buildings or modifiers. Note that these provinces have to be states, or they will not count. The base tax of all current vassals also adds to the economic base of the nation offering vassalization.

### Break vassalization

• Through a peace deal: when suzerain loses a war.
• Through diplomacy: a suzerain can chose 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 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.

### 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%.[2] A overlord can increase its ‘vassals tax efficiency’ by the following:

Conditions
+33% as iqta
+25% as elective monarchy or feudal monarchy
+10/20/30% as tribal kingdom (depending on government rank)
+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:

+50%
• 进攻-行政: 附庸税收政策
+25%
• 卡内姆 博尔努 传统
• 中美洲 传统
• 影响 理念 1: 朝贡体系
• 足利 理念 7: 改革幕府体系
• 波斯尼亚 理念 5: 王公们的领地
• 阿瑜陀耶 野心
• 影响-经济: 附庸义务法案
• 影响-扩张: 海外领土
• 影响-质量: 行政一体化法案
+20%
• 马里 理念 1: 恢复马里的宗主权
• 隆达 野心
• 赞比西 野心

Events:

Event modifier Trigger Duration
+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.

The overlord can increase the paid vassals tax by +50% if he asks for scutage in exchange for the renunciation of military support from the vassal.

### Vassal force limit contribution

Vassals increase the suzerain's land force limit by 1[3] and marches by 2[4], but not the naval force limit. This contribution can be increased by the following.

Ideas and policies:

+100%
• 影响 理念 7: 边界领主
• 足利 理念 7: 改革幕府体系
• 波斯尼亚 理念 5: 王公们的领地
• 影响-贵族: 自治庄园
• 影响-经济: 附庸义务法案
• 影响-进攻: 统一指挥

Decisions and events:

Event modifier Trigger Duration
+100% Firm Hand Influence ideas event: “A Firm Hand for 10 years.

## 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 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, royal marriages, trust, and having the same dynasty.

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.

## Subject interaction

This is done through the Subject Interaction section of the Subject Menu.

## Annexation

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:

1. 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 .
2. Vassal opinion of overlord is at least 190.
3. Liberty desire is less than 50%.
4. Vassal is at peace.
5. Vassal has control of its capital.

Annexation progress of vassals appears in the diplomacy interface as a small vertical 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:

#### Cost

The total cost of annexation is 8 diplomatic power per development of the vassal. This cost is increased by the hostile core-creation cost modifiers of the vassal's corresponding provinces, and decreased by administrative efficiency and modifiers that reduce annexation cost. These modifiers are displayed below:

−25%
• 影响 理念 3: 整合精英
−20%
• 影响-行政: 附庸吞并法案
−15%
• 奥地利 理念 1: 帝国雄心
• 赞比西 理念 6: 希雷河谷的财富
• 纳克索斯 野心
−10%
• 财阀-影响: 完整主权法案

The full formula for diplomatic annexation cost is:

${\displaystyle {\text{dip point cost}}={\text{floor}}\left(\sum _{\text{per province}}\left[8\cdot {\text{development}}\cdot (1-{\text{administrative efficiency}})\cdot \left(1+\sum {\text{annexation cost modifiers}}\right)\cdot \left(1+\sum {\text{local coring cost modifiers}}\right)\right]\right)}$

Note that even with a −100% modifier to annexation cost, annexation will still cost a minimum of 12.5% of the full annexation cost.

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 six months of one another: since an event such as that giving the Annexed Vassals modifier can be postponed for up to six 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 also avoid both long periods with the penalty and short periods with an extreme penalty.

#### Speed of annexation

The overlord invests diplomatic power into the annexation process each month at the following rate:

If the total is 0 or negative, annexation will pause, but not reverse.

#### Effects

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.
• -30 relations with other vassals. Stacks. Does not apply to marches.
• -25 relations with other HRE members, if the vassal was in the Holy Roman Empire.
• 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.

### Preparations

• 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 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.

### 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. This will reduce the vassal's liberty desire by half of the total development granted to it, easily offsetting the increase in liberty desire that vassals get from becoming more powerful and can even negate the +25%/+50% liberty desire taken on by vassals who have more than 100 or 300 development, respectively - feeding a vassal even 200 development worth of land will reduce its liberty desire by 100%. 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.

#### 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.

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

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).

## Achievements

For the Glory
Diplo-annex a vassal.

## Footnotes

1. See in /Europa Universalis IV/common/defines.lua PEACE_COST_BECOME_VASSAL = 1
2. See in /Europa Universalis IV/common/static_modifiers/00_static_modifiers.txt (Static_modifiers#Base_values).
3. See in /Europa Universalis IV/common/static_modifiers/00_static_modifiers.txt (Static modifiers#Vassal subject).
4. See in /Europa Universalis IV/common/static_modifiers/00_static_modifiers.txt (Static modifiers#March subject).
附属国 自定义附庸 • 殖民领 • 卫戍国 • 君合国 • 贸易公司 • 朝贡国 • 附庸国 使者 • 军事同盟 • 关系 • 外交回应 • 间谍 • 殖民 • 教宗 • 神圣罗马帝国