Difference between revisions of "Diplomacy"

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(Proclaim guarantee: Updated to 1.18, added information about being called in a co-belligerant.)
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Becoming a {{icon|protectorate}} of a western nation makes a country a subject of said nation. While the player nation receives military protection and reduced {{icon|technology cost}}[[technology cost]], it also is required to transfer {{red|50%}} of its trade {{icon|foreign trade power}}[[trade power]] to the overlord and join all colonial wars.
Becoming a {{icon|protectorate}} of a western nation makes a country a subject of said nation. While the player nation receives military protection and reduced {{icon|technology cost}}[[technology cost]], it also is required to transfer {{red|50%}} of its trade {{icon|foreign trade power}}[[trade power]] to the overlord and join all colonial wars.
==== Proclaim guarantee ====
==== [[File:guaranteed.png|24px]] Proclaim guarantee ====
[[File:guaranteed.png|24px]] Guaranteeing a nation calls the guarantor to war if the target nation is directly attacked by another nation. The guarantor will not be called to war if the guaranteed nation is called into another war as an ally. The relation uses a {{icon|diplomatic relations}}[[#Diplomatic_relations_cap|diplomatic relations]] slot and lasts until revoked or a call to arms from the target is declined(?). A call to arms from a guarantee functions identically to a defensive call to arms in an alliance and carries the same penalties if declined. Guarantees can be revoked at will, which gives the former guarantor a truce on the formerly guaranteed country (but not vice versa). It is only possible to guarantee countries that are significantly weaker than the guarantor - protection from a weaker nation will not be taken seriously.
Guaranteeing a nation calls the guarantor to war if the target nation is directly attacked by another nation. The guarantor will not be called to war if the guaranteed nation is called into another war as an ally, unless they are called in as a co-belligerant. The relation uses a {{icon|diplomatic relations}}[[#Diplomatic_relations_cap|diplomatic relations]] slot and lasts until revoked or a call to arms from the target is declined. A call to arms from a guarantee functions identically to a defensive call to arms in an alliance and carries the same penalties if declined. Guarantees can be revoked at will, which gives the former guarantor a truce on the formerly guaranteed country (but not vice versa). It is only possible to guarantee countries that are significantly weaker than the guarantor - protection from a weaker nation will not be taken seriously.
==== Send warning ====
==== Send warning ====

Revision as of 06:14, 7 November 2016

The diplomacy interface, as the player nation, viewing France

Diplomacy in EU4 is the system that involves all relations and actions with other nations. Relations can be increased through alliances, coalitions, common wars, common rivalries, decisions, events and having a diplomat improve relations. Relations are decreased by declaring war, being rivals, sending insults, having a different religion, breaking/dishonoring an alliance, events and decisions. Diplomacy is a bilateral system and will affect relations on both sides of an agreement.

Reasons for a nation's opinion of another are displayed in tooltips wherever opinion is shown. The total is capped at +200/-200.

Diplomacy is conducted by diplomats, and the diplomatic options available to diplomats depends on a country's technology and ideas. Diplomatic options are split in seven categories: alliance, influence, relations, dynastic, covert, economy and access. The emperor of the Holy Roman Empire has an extra category: Emperor actions. The Papal controller also has an extra category: Papal actions. The declare war and sue for peace diplomatic options are found outside of these categories.


A Diplomat.png diplomat is required to perform most diplomatic actions. Some actions - improving relations, annexing a vassal, building up a spy network and counterespionage - will occupy a diplomat indeifinitely or until completion of the task, unless the diplomat is manually recalled. Actions that will occupy a diplomat for a period of time will display a diplomat icon (Diplomat.png) on their button. Other actions are immediate.

When initiating a mission, a diplomat takes one day to reach the target country and begin its mission. After completing a mission, a diplomat will be unavailable while he travels back home, the time which scales based on the distance between one's capital and that of the target country. The precise travel speed of diplomats is 20 distance per day.

Gaining diplomats

Each country has with 2 Diplomat.png diplomats by default. Additional diplomats may be gained through the following ideas, policies, and triggers:

Diplomat.png Traditions Ideas Bonuses Policies
  • Aachen traditions
  • Ajami traditions
  • Hausan traditions
  • Kurdish traditions
  • Mori traditions
  • Samtskhe traditions
  • Sligonian traditions
  • Thüringian traditions
  • Westphalian traditions
  • Aristocratic idea 6: International Nobility
  • Diplomatic idea 1: Foreign Embassies
  • Diplomatic idea 3: Grand Banquets
  • Espionage idea 2: Agent Training
  • Aq Qoyunlu idea 5: Expansive Diplomacy
  • Assamese idea 7: Ahom Diplomacy
  • Asturian idea 3: Asturian Aristocracy
  • Ayutthayan idea 4: Embassies
  • Baden idea 3: Active Diplomacy
  • Bosnian idea 6: Flexible Diplomacy
  • Butuan idea 7: Long Range Diplomacy
  • Cherokee idea 7: Cherokee Emperor
  • Chagatai idea 6: Scheming Nobility
  • Cilli idea 3: Political Maneuvering
  • Circassian idea 6: Steppe Diplomats
  • Gelre idea 1: Feudal Elevation
  • Iroquois idea 4: Keepers of the Fire
  • Karamanid idea 4: Seize the Opportunity
  • Krakowian idea 7: The Free City
  • Lorraine idea 4: Flexible Diplomacy
  • Luxembourg idea 7: Rivals On All Sides
  • Manx idea 1: The Stanleys
  • Medri Bahri idea 3: Diplomatic Flexibility
  • Moluccan idea 7: Pragmatic Diplomacy
  • Mushasha idea 6: Outward Pragmatism
  • Nanbu idea 3: Connection With Kyoto
  • Odoyev idea 2: Dynamic Diplomacy
  • Ragusan idea 3: Patronage
  • Rostov idea 6: Political Influence
  • Saxon idea 1: Albertine and Ernestine lines
  • Shawnee idea 6: Far−Reaching Relations
  • Shiba idea 3: Consolidation of the Kanrei Position
  • Shoni idea 3: Diplomacy through Tsushima
  • Siddi idea 5: Siddi Diplomacy
  • Trebizondian idea 4: Komnenoi Princesses
  • Tyrone idea 5: Catholic Diplomacy
  • Utsunomiya idea 1: Fujiwara Descendant
  • Venetian idea 2: Printing Industry
  • Vijayanagar idea 6: Adroit Diplomacy
  • Yamana idea 1: Descendant of Nitta
  • Yemeni idea 7: Foreign Embassies
  • Antemoro ambition
  • Mapuche ambition
  • West African ambition
  • Administrative-Diplomatic: The Recordkeeping Act
  • Diplomatic-Aristocratic: The Tenures Abolition Act
  • Diplomatic-Defensive: The Diplomatic Defense Act
  • Espionage-Economic: The Foreign Support Act
  • Espionage-Offensive: The Black Chamber Act
  • Innovative-Espionage: The Espionage Act

Diplomat.png Triggers

Diplomatic relations cap

The number of other countries a nation can have diplomatic agreements with is limited. Each relation over the cap costs 1Diplomatic power.png diplomatic monarch point per month. The limit only counts for the number of different countries with whom an agreement has been closed, not the number of agreements. Having multiple agreements with a single nation only counts as one diplomatic relation.

Agreements that count towards the cap include:

Agreements that do not count toward the cap include:

Increasing the diplomatic relations cap

The base diplomatic relations cap is 4 diplomatic relations.[1] It is affected by the following:

Diplomatic relations.png Conditions
+4 Shogunate government
-2 Duchy rank Tribal government Duchy

Ideas and policies:

Diplomatic relations.png Traditions Ideas Bonuses Policies
  • Provençal idea 5: Public Weal
  • Antemoro traditions
  • Brunswicker traditions
  • Burgundian traditions
  • Isshiki traditions
  • Jaunpuri traditions
  • Ladakh traditions
  • Kiwi traditions
  • Milanese traditions
  • Muscovite traditions
  • Nubian traditions
  • Palatine traditions
  • Savoyard traditions
  • Timurid traditions
  • Diplomatic idea 2: Cabinet
  • Expansion idea 5: Additional Diplomats
  • Influence idea 4: Buffer States
  • Asakura idea 1: Hidden Diplomacy
  • Austrian idea 6: Austrian Court
  • Berber idea 6: Dual Diplomacy
  • Bosnian idea 4: Italian Connections
  • Butuan idea 1: Indianized Society
  • Colognian idea 6: Shifting Alliances
  • Danziger idea 1: Danzig Law
  • Desmondian idea 5: Fierce Independence
  • English idea 3: Secretaries of State
  • French idea 1: French Language in All Courts
  • French ducal idea 6: French Enlightenment
  • German idea 6: Thurn und Taxis
  • Goslar idea 7: Joining the Leagues
  • Greek idea 6: Philhellenism
  • Hanoverian idea 6: Hanoverian Chancery
  • Hausan idea 1: Heirs of Bayajida
  • Herzegovinian idea 7: Shifting Allegiances
  • Hormuz idea 4: Far-reaching Diplomacy
  • Imagawa idea 5: Triple Alliance
  • Italian idea 6: Italian Diplomacy
  • Knights Hospitaller idea 3: The Tongues of Knights
  • Krakowian idea 7: The Free City
  • Kurdish idea 4: Active Diplomacy
  • Lan Na idea 7: Dynastic Spread
  • Leinster idea 6: The Geraldine League
  • Lur idea 7: Foreign Trade Ties
  • Luxembourg idea 6: The Grand Duchy of Luxembourg
  • Lüneburger idea 6: Adroit Diplomacy
  • Manipur idea 6: Bengali Influence
  • Mantuan idea 6: Mantuan Royal Ties
  • Mazovian idea 3: Between Monk, Eagle and Purse
  • Mori idea 3: Diplomatic Intrigues
  • Orleanaise idea 7: French Language in All Courts
  • Polotskian idea 6: Diplomatic Initiative
  • Québécois idea 3: Relations with the First Nations People
  • Sardinian-Piedmontese idea 1: Diplomatic Flexibility
  • Satake idea 5: Eastern Coalitions
  • Saxon idea 5: Corpus Evangelicorum
  • Swabian idea 4: The Swabian League
  • Swahili idea 7: Familiar Presence Abroad
  • Three Leagues idea 1: The League System
  • Thüringian idea 7: Expansive Marriage Policy
  • Transylvanian idea 7: Anti-Habsburg Policies
  • Tunisian idea 2: Dual Diplomacy
  • Wurzburgian idea 1: Legacy of the Imperial Diets
  • Uesugi idea 1: Kanto Kanrei
  • Ulmer idea 2: Schwäbischer Bund
  • Yamana idea 3: Mediate Succession Disputes
  • Aachen ambition
  • Ajami ambition
  • Imperial German ambition
  • Kikuchi ambition
  • Kuban ambition
  • Mossi ambition
  • Native ambition
  • Diplomatic-Defensive: The Diplomatic Defense Act
  • Humanist-Influence: The Foreign Aid Act
  • Influence-Offensive: Foreign Conscription Centers

Certain events may also give a temporary increase in the relations cap.

Diplomatic reputation

A nation's Diplomatic reputation.png diplomatic reputation represents its overall diplomatic ability and credibility. Diplomatic reputation is visible in the diplomacy window of the country screen.


Diplomatic reputation positively affects both subject relations and relations with sovereign nations.

With subject nations, each point of diplomatic reputation gives:

  • +5% chance to inherit lesser partner in a personal union
  • +1 Diplomatic power.png diplomatic power used per month while annexing vassals or union partners
  • -3% to the Liberty desire.png liberty desire of all subject nations

With other countries, each point of diplomatic reputation gives the following bonuses when accepting diplomatic proposals:

Action Bonus
Offer Alliance 5
Offensive Call to Arms 5
Royal Marriage 5
Offer Vassalization 3
Establish and Request Protectorate 3
Transfer Trade Power 3
Ask for Military Access 3
Ask for fleet basing ights 3
Request to share maps 5
Demand unlawful territory 3
Grant free city status 3

Gaining diplomatic reputation

Diplomatic reputation can be increased by the following modifiers and ideas:


National ideas and traditions, idea groups and policies

Diplomatic reputation.png Traditions Ideas Bonuses Policies
  • Holy Roman traditions
  • Diplomatic idea 5: Experienced Diplomats
  • Influence idea 5: Diplomatic Influence
  • Aachen idea 7: Congresses of Aachen
  • Austrian idea 4: Habsburg Dominance
  • Kiwi idea 7: Pokarekare Ana
  • Roman idea 2: Legacy of Rome
  • Jerusalem idea 7: Cosmopolitan Nobility
  • Ansbach traditions
  • Cilli traditions
  • Date traditions
  • Delhian traditions
  • French traditions
  • Goslar traditions
  • Hessian traditions
  • Iroquois traditions
  • Novgorodian traditions
  • Odoyev traditions
  • Papal traditions
  • Provençal traditions
  • Rajput traditions
  • Ryukyuan traditions
  • Silesian traditions
  • Sukhothai traditions
  • Yamana traditions
  • Afghan idea 4: Afghan Diaspora
  • Ajami idea 4: Persian Language and Court Culture
  • Antemoro idea 4: Ombiasa
  • Arakanese idea 5: Buddhist Sultans
  • Arawak idea 6: Enemy Of My Enemy
  • Armenian idea 3: Border Nation
  • Athenian idea 3: Athenian Pragmatism
  • Ava idea 6: Keep the Shan in Line
  • Bahmani idea 5: Takht-e-Firoza
  • Barbary Corsair idea 4: Mazmorras
  • Bayreuther idea 1: Hohenzollern Margrave
  • Berg idea 4: The Seat of the Electorate
  • Betsimisaraka idea 7: European Diplomacy
  • Brandenburg idea 5: Seat of the Old Emperors
  • Bremish idea 1: Lex Saxonum
  • Breton idea 6: League of the Public Weal
  • Brunswicker idea 1: The Welfian Dynasty
  • Butuan idea 4: Butuan Goldwork
  • Castilian idea 5: Infantas
  • Chachapoyan idea 4: Women Diplomacy
  • Chiba idea 1: Taira Lineage
  • Chinese idea 7: Middle Kingdom
  • Clevian idea 4: Strategic Marriages
  • Creek idea 6: Muscogee Neutrality
  • Cypriot idea 4: Lusignan Diplomacy
  • Deccani idea 6: Jewels of the Nizams
  • Dhundhari idea 2: Seek the Protection of Great Powers
  • Dortmund idea 4: The Emperor's Favorite
  • Ethiopian idea 4: Diplomatic Demeanor
  • Ferraran idea 4: Margraves of Este
  • Frankfurter idea 2: Seat of Imperial Elections and Coronations
  • Genevan idea 2: Neutral Grounds
  • Georgian idea 7: Georgian Embassies
  • German idea 3: Reichskreis
  • Great Shun idea 2: The Dashing King
  • Greek idea 6: Philhellenism
  • Gujarati Princedom idea 4: Rajput Dynasties
  • Herzegovinian idea 4: Accommodation with the Ottoman Turks
  • Holstein idea 2: Between a Kingdom and the Empire
  • Hormuz idea 4: Far-reaching Diplomacy
  • Huron idea 5: Missionary Welcome
  • Isshiki idea 3: Bridge of Heaven
  • Khorasani idea 1: Land of the Rising Sun
  • Kievan idea 2: Heritage of the Rus'
  • Kildarean idea 1: Lords Deputy
  • Kitabatake idea 3: Supporters of the Emperor
  • Kongo idea 4: Diplomacy With European Monarchs
  • K'iche idea 4: The Ball Game
  • Liège idea 5: The Prince-Bishop's Palace
  • Luban idea 7: Prestige of the Mulopwe
  • Luxembourg idea 1: Imperial Legacy
  • Lüneburger idea 2: The Welfian Dynasty
  • Manipur idea 7: Far-Reaching Diplomacy
  • Mantuan idea 1: Free Imperial City of Mantua
  • Mapuche idea 6: Peace Parliaments
  • Maravi idea 2: Mlira Cult
  • Meath idea 2: Foreign Nationals
  • Mesoamerican idea 3: The Ball Game
  • Montferrat idea 1: Cousins to Kings and Emperors
  • Moravian idea 1: Margraviate of Moravia
  • Muscovite idea 7: Descendants of Byzantine Emperors
  • Münster idea 4: Cities of peace
  • Mysorean idea 7: Dynamic Diplomacy
  • Nepali idea 1: The Divya Upadesh
  • Ormond idea 2: The Courts of Europe
  • Ouchi idea 1: Descendant of Baekje
  • Pacific Northwest idea 3: Totem Poles
  • Palatinate idea 1: Imperial Vicar and Archsteward
  • Pegu idea 7: Mon Diaspora
  • Rigan idea 5: Free City of Riga
  • Saxon idea 3: The Zwinger
  • Shoni idea 1: Vice-Minister of Dazai-fu
  • Sinhalese idea 4: Centre of Learning
  • So idea 5: Tough Negotiators
  • Swahili idea 7: Familiar Presence Abroad
  • Theodorian idea 3: Russian Aristocracy
  • Thomondian idea 1: Fierce Rivalry
  • Three Leagues idea 3: The Grey League
  • Tibetan idea 5: Potala Palace
  • Trebizondian idea 4: Komnenoi Princesses
  • Ulster idea 3: Civilist of the Irishry
  • Urbinate idea 5: The Book of the Courtier
  • Vindhyan idea 1: Rajput Connections
  • Wallachian idea 1: Cunning Diplomacy
  • West Indies idea 6: Interconnected Relations
  • Wurzburgian idea 2: Duke in Franconia
  • Yarkandi idea 3: Tarikh-i-Rashidi
  • Yaroslavlyian idea 2: Third Option
  • Assamese ambition
  • Epirote ambition
  • Medri Bahri ambition
  • Nuremberger ambition
  • Pisan ambition
  • Rostov ambition
  • Sadiyan ambition
  • Tirhuti ambition
  • Diplomatic-Expansion: Commercial Embassies
  • Diplomatic-Offensive: The Underhanded Diplomacy Act
  • Diplomatic-Quality: Professional Diplomatic Corps
  • Diplomatic-Quantity: The Pen Relies on The Sword Act
  • Humanist-Influence: The Foreign Aid Act
  • Innovative-Diplomatic: The Diplomatic Cooperation

Diplomatic actions


Main article: Warfare

Declaring war initiates a military conquest against the target country. A casus belli can be selected and the allies of both sides are shown in the declare war screen. Winning battles, achieving the wargoal, and occupying provinces accumulates War score.pngwar score for both parties, by which peace terms may be agreed upon. At war a country can offer a peace deal (sue for peace) or an unconditional surrender.

Alliance actions

Form coalition against

Main article: Alliance#Coalition

A Coalition.png coalition is an alliance of nations who have bonded together against a common enemy because of this enemies' very high Aggressive expansion impact.png aggressive expansion. Coalitions members will automatically be offensively and defensively called to arms in any direct war between a coalition member and the coalition target.

Offer alliance

Main article: Alliance

An Alliance.png alliance is a military agreement of mutual support in wars between two nations. The strength of an alliance is based on trust and favors with the alliance partner.

Support independence

Nations may support the independence of a nation if the target nation is a subject nation and has a Liberty desire.pngliberty desire of over 50%. If the target nation declares a war of independence, all nations supporting its independence will automatically ally the target nation and join the war against the former overlord of the now (temporarily) independent nation.

Offer condottieri

Main article: Condottieri

A nation may rent out their armies to another nation in exchange for payment, while maintaining manual control of the army. A maximum of 20 regiments can be rented out simultaneously.

Influence actions

Enforce peace

The enforce peace action demands that the leading attacker in a war make a white peace with the leading defender. Refusal will bring the enforcing nation into the war on the side of the defender. The following conditions must be met in order to enforce peace:

  • The enforcer must not have a truce with the leading attacker.
  • The enforcer must have at least +100 relations with the leading defender.
  • The attacker must have -25% War score.png warscore or better.

Enforce peace is a useful method for entering wars without triggering any automatic defensive call to arms from the opponent. For example, European powers outside the Imperial authority.pngHoly Roman Empire can use enforce peace on empire members to enter wars against them without having to fight the Emperor. Enforce peace can also turn the tides against a rival's offensive war.

Additionally, enforce peace may be used by an overlord to take command of a Icon protectorate.pngprotectorate's offensive war, in which case the overlord becomes the leading attacker.

Offer vassalization

Main article: Vassal#Offer vassalization

Vassalization makes the target nation a subject nation of the country that offered it. Vassals are automatically called to their overlord's wars and pay a portion of their Income from vassals.png tax income.

Break vassalization

Breaking vassalization cancels a subject nation's vassalage and makes them independent. This action costs Prestige.png -25 prestige and -200 relations penalty with the former vassal, and results in a truce of 5 years with the former overlord. Vassalization cannot be canceled when a truce exists with the target.

Designate march

Main article: March

Designating a vassal as a March icon.png march grants it substantial military bonuses. Marches do not pay Income from vassals.pngtax income to their overlord, and cannot be diplomatically annexed.

Revoke march

Main article: March

Revoking a march changes it to normal Vassal.png vassal status, allowing for it to be annexed. This action costs Icon stability.png -1 stability and results in a -200 relations penalty with the subject.

Annex vassal

Main article: Vassal#Annexation

Diplomatic annexation incorporates a client state or Vassal.pngvassal into the overlord's domain, resulting in direct control of the former subject's territory and military. This action occupies a Diplomat.pngdiplomat for its duration and costs Diplomatic power.png diplomatic power.


Main article: Personal Union#Integration

Diplomatic integration incorporates a junior parter of a Personal union.pngpersonal union into the senior partner's realm. Like diplomatic annexation of vassals and client states, completion results in control of the junior partner's territory and military, but also gains control of the junior partner's Vassal.pngvassals, Subject colony icon.pngcolonial nations, and Icon protectorate.pngprotectorates.

Diplomatic integration of a junior partner in a personal union follows nearly the same principles for requirements, cost, speed, and effects as diplomatic annexation of a vassal.

Establish protectorate

Main article: Protectorate#Establish a protectorate

Establishing a Icon protectorate.png protectorate makes the target nation an entity similar to a Subject colony icon.pngcolonial nations. Protectorates are technologically inferior subject stations that do not occupy a relations slot. They transfer 50% of their Trade power abroad.pngtrade power to their overlord, while being militarily protected by their overlord and receiving a discount to Technology cost.pngtechnology cost.

Request protectorate

Main article: Protectorate#Request a protectorate

Becoming a Icon protectorate.png of a western nation makes a country a subject of said nation. While the player nation receives military protection and reduced Technology cost.pngtechnology cost, it also is required to transfer 50% of its trade Trade power abroad.pngtrade power to the overlord and join all colonial wars.

Guaranteed.png Proclaim guarantee

Guaranteeing a nation calls the guarantor to war if the target nation is directly attacked by another nation. The guarantor will not be called to war if the guaranteed nation is called into another war as an ally, unless they are called in as a co-belligerant. The relation uses a Diplomatic relations.pngdiplomatic relations slot and lasts until revoked or a call to arms from the target is declined. A call to arms from a guarantee functions identically to a defensive call to arms in an alliance and carries the same penalties if declined. Guarantees can be revoked at will, which gives the former guarantor a truce on the formerly guaranteed country (but not vice versa). It is only possible to guarantee countries that are significantly weaker than the guarantor - protection from a weaker nation will not be taken seriously.

Send warning

Sending a warning to a target country results in a defensive call to arms if the target attacks one of the warner's neighbors. Rejecting this call to arms only incurs a penalty to trust with relevant nations. The list of neighbors for any nation can be found in its diplomacy tab by filtering its relation list to neighbors only. A country cannot warn another country it is already warned by, or that is not significantly weaker. A warning lasts for 20 years and can be issued again once it expires.

Threaten war

Threaten war is a diplomatic action which lets a nation demand a province that it has a claim or core on. If the demand is accepted, the province is transferred to the demanding nation. If the demand is not accepted a war with the Casus belli.png Conquest casus belli for said province. War cannot be threatened over a country's Capital.png capital (it cannot be targeted at an OPM) or if a truce exists with the target country. Successfully demanding a province will cause the threatening country to gain Aggressive expansion impact.pngaggressive expansion as if the province had be conquered in a peace deal and the target nation to lose -10 Prestige.pngprestige. This also creates a 5-year truce between the two nations. A country will relinquish a province if the relative strength of the demanding country's alliance outweighs the relative worth of the province and the alliances of the threatened nation. The AI is more willing to give up provinces that the demanding country has a core on, and much less willing to give up provinces if that country has recently demanded another province.

Factors that influence the AI's willingness to giving up a province are:

Factor Effect
Base value: -20
Province is not a core of the threatening nation: -20
Relative strength of alliances: -100 to +100
Relative worth of province to target's entire development: -1 to -200
Recently gave in to threat: Base of -120, increasing by +1 per month after truce ended
The Continuation of Diplomacy icon
Successfully use Threaten War to gain a province from another nation.

Relations actions

See also: Relations

Improve relations

Improve relations.png Improving relations sends a diplomat to the target country to improve relations over time. Relations can be improved up to +200 for subjects and up to +100 for all other nations. Improved relations decay by -3 on the first day of each year if there is no diplomat currently improving relations with the target country. The rate of relations improvement is highest when relations are 0, and decreases as the difference increases. This rate can be further improved by the improve relations modifier. ""Improve relations"" should not be confused with "Better relations over time", which makes makes negative relations decay more quickly and positive relations decay slower.

When sending a diplomat to improve relations for the first time or when the improved relations value has decayed to 0 doubly improved opinion is gained on the first tick. The rest of the relations improvements take place at the end of each month.

Send an insult

Sending give the target country the Casus belli.png Diplomatic insult casus belli on the insulter for 1 year and lower relations by -50, decaying by +5 per year. Insults are useful for negating the -1 Icon stability.png stability hit of declaring war on nations that have +100 relations of the aggressor. Insulting a rival also grants +5 Power projection.png power projection, decaying by -1 per year, provided that the insulter neither has a truce with them nor already has power projection from a previous insult.

Dynastic actions

Royal marriage

For the dynastic effects of royal marriage, see Ruler#Royal marriage
For information on personal unions, see personal union

Countries ruled by monarchs may arrange Royalmarriage.png royal marriages with others. This improves relations by +25 while in effect. Attacking a country with whom a nation has a royal marriage results in -1 Icon stability.png stability and +1 Icon war exhaustion.png war exhaustion.

Upon the death of a CatholicismChristian monarch with no heir, a ruler from the dynasty of a more prestigious country that shares a royal marriage may rise to the throne. If the countries already share a dynasty, a Personal union.png personal union may result instead. Personal union partners function militarily like vassals. They do not pay a portion of their tax income but may be inherited. Higher Prestige.png prestige increases chances of gaining the crown of a royal marriage partner for a country's dynasty, either independently or as a personal union.

Royal marriages are unavailable to Government theocracy.pngtheocracies and Government republic.pngrepublics, with the exception of the Dutch Republic. Christians may only marry other Christians. All non-Christians may marry each other, but personal unions will only occur for Christian nations.

The factors that influence a nation's acceptance of a royal marriage proposal are:

Factor Effect
Attitude towards proposer Friendly attitude Friendly: +40
Protective attitude Protective: +40
Threatened attitude Threatened: +10
Neutral attitude Neutral: -20
Domineering attitude Domineering: -980
Hostile attitude Hostile: -1000
Outraged attitude Outraged: -1000
Rivalry attitude Rivalry: -1000
Nation opinion about proposer Positive: +0.25 per point
Negative: -0.25 per point
 Same culture group +20
Same religion +5
Neighbors +5
Proposer's diplomatic reputation +5 per point
Distance between borders -0.1 per distance between borders

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

Until death do us apart icon
Secure a Royal Marriage with another country.

Break royal ties

Breaking royal ties ends a royal marriage. This results in -1 stability and -1 prestige. Furthermore the relation with the target country is decreased by -75. The stability cost may be negated by completing Diplomatic idea group.pngDiplomatic ideas or being the Curia Controller. The death of the ruler who proposed the marriage will also end a royal marriage without penalty.

Claim throne

For information on improving chances of obtaining a personal union, see Personal Union

Claiming a throne gives the "claim on throne" CB, a military means of forcing a personal union.

The requirements to claim a throne are as follows:

  • Target has a Royalmarriage.png royal marriage
  • Target shares the same dynasty as claimant
  • Target has a weak claim heir or no heir
  • Claimant has more Prestige.pngprestige than target

Claiming the throne of a country results in the following diplomatic effects:

  • -50 relations with other royal marriage partners
  • -100 relations with the target country, and incur a loss of Prestige.png -20 prestige.
  • Claimant gains Casus belli.png "Claim on Throne" casus belli against the target. The War score.png war score cost to enforce a Personal union.png personal union is 84% regardless of the target's size.

Note that while some allies may be willing to join a conquest war, they will not join a claim on throne war or succession war, due to opposition to a successful personal union. The gained casus belli lasts until the target country produces an heir with a strong claim or a new heir rises to the throne.

The claim throne diplomatic action is only possible for Christian nations as no other religious group allows personal unions. While the Government republic.png Dutch republic, oligarchic republic, and elective monarchy can have royal marriages, their thrones cannot be claimed as they do not have heirs.

Support heir

Supporting an heir is an action that can be initiated on nations with an elective monarchy (which can only be gained by event for Flag of Poland Poland and the Flag of Commonwealth Commonwealth, or by using a custom nation). Any nation that is in the same religious group as the country with elective monarchy can support an heir.

In an elective monarchy, each nation that has supported its heir in the current election cycle has a possible heir to the throne with an associated amount of support. A diplomat must be sent in order to support a nation's own heir in an elective monarchy,

The probability of increasing the heir's support every month by 1 is as follows:

The elective monarchy may also increase support for its own heir by 5 points at the cost if of -10 Prestige.png prestige.

Upon the death of the elective monarchy's ruler, the heir with the most support rises to the throne in the elective monarchy.

If a foreign heir arises, the country that provided the heir gains:

  • +25 Prestige.png prestige
  • +10 Legitimacy.png legitimacy
  • +24x Administrative power.png administrative, Diplomatic power.png diplomatic, and Military power.png military power of the new ruler

If a local noble rises to the throne, the elective monarchy loses -20 relations with all countries that supported an heir in the election.

Covert actions

Main article: Espionage

Diplomats can be send to other nations to build up a spy network, or to practice counterespionage and increase the chance of catching spies sent by the target nation. When a spy network has grown enough, espionage actions can be undertaken, which do not require sending a diplomat. Most of the espionage actions require certain ideas from the espionage idea group in order to become available. Actions that do not need this group are fabricate claim, support rebels and justify trade conflict. Completing the espionage group will give access to various powerful actions. One example is the vetting idea, the first of the idea group, which grants a discount to technology cost depending on the difference in technology level between the home country of the spies and the target country, as well as the size of the spy network there. Covert actions are described in more detail on the Espionage page.

Economy actions

See also: Economy

Transfer trade power

Ask a target non-subject nation to transfer a percentage of its trade power to the proposer. While a transfer of trade power is active, the two nations involved cannot declare war on each other, and will also receive a mutual relation bonus of +20 per 100% of power transferred. The agreement does not count towards each country's diplomatic relations limit.

The factors that influence an AI nation's desire to accept a request to transfer trade power are

Factor Effect
Proposer military power compared to nation +80 max
Proposer base tax compared to nation +20 max
Attitude towards proposer Threatened attitude Threatened: +20
Friendly attitude Friendly: +10
Hostile attitude Hostile: -100
Proposer is not allied with or guaranteeing nation -50
Nation opinion of proposer +0.1 per positive relation
Diplomatic reputation.png Diplomatic reputation Positive: +1 per point
Negative: -2.5 per point
Trust +0.2 per positive point
Amount of power asked for Starts at +20 with 10% power. Increases for each percentage point between
10–40%: -1
41-60%: -3
61-80%: -5
81-100%: -7
Number of countries transferring trade power to proposer -10 per transfer trade power agreement
Distance between borders

Issue embargo

Reduces the Trade power.png trade power of the target country in every trade node the embargoing country has trade power in, depending on several factors. Embargoing a rival grants power projection. Embargoing a non-rival gives a penalty to trade efficiency, but can give a net gain in trade power share (and hence income) if the other country is very dominant in an important node.

The following bonuses apply to embargo efficiency:

Embargo efficiency.png Traditions Ideas Bonuses Policies
  • Espionage idea 6: Privateers
  • Vermont idea 2: The Boston Tea Party
  • Betsimisaraka idea 2: Pirate Ports
  • Cebu idea 5: 'The Place for Trading'
  • Cypriot idea 7: Raid Turkish Commerce
  • Malagasy idea 3: Pirate Ports
  • Mindanao idea 7: Pirates of Mindanao
  • Montenegrin idea 4: Balkan Gusars
  • Naxian idea 3: Archipelago Of Opportunities
  • Pomeranian idea 1: Legacy of Pirates

Send gift

Allows a nation to send money to improve relations with a country, up to a maximum of +25. The gift amount can be adjusted in increments of Gold Icon.png 25 ducats. The effect of the gift is:

relation bonus = 2.4 * ducats gifted / monthly income of target country

The final value is rounded down to the nearest integer. The relation bonus will last for 5 years. Additional gifts sent during this time will have no effect unless it would increase relations more than previous gifts did.

Loan offer

Allows a nation to loan out money to other countries for interest. When the loan is due to be repaid, the loan-taker can instead choose to keep the ducats. This will give the loan-giver a casus belli. This is disabled for any AI country, as it is basically a "free CB" button due to the AI's misuse of loans.

Give subsidies

Transfer a specified amount of money each month to the target country for a certain duration. The sender may transfer between Gold Icon.png 0.1 ducats and +50% of its monthly income to the target country each month, adjustable in increments of 1% of its monthly income. The duration of the subsidy can be set between 10 and 400 years, adjustable in increments of 10 years.

Maintaining subsidies will improve the target country's relations with the subsidiser each month, up to a maximum of +15. The accumulated relation bonus is completely removed when the subsidy is cancelled or expires. Since there is otherwise no penalty for terminating a subsidy early, it is generally good practice to set a long subsidy duration unless diplomat time is severely constrained. The relation bonus is

yearly relations increase = 12 * monthly subsidy / target country's total monthly income

All monthly income mentioned in this section refers to the monthly income as reported in the ledger. Be aware that the target country's total monthly income will therefore include this monthly subsidy once the ledger is updated after the establishment of the subsidy. This imposes significant diminishing returns on the relation benefits of a large subsidy, and encourages one to maintain smaller subsidies over a longer time frame instead.

Example: Country A has a monthly income of 10 ducats, and country B provides it with a monthly subsidy of 5 ducats. The reported yearly relations boost will start at +6 per year (B's subsidy is 1/2 of A's income), then immediately drop to +4 per year after the first month (the subsidy is now 1/3 their income).

Subsidies do not consume a diplomatic relations slot. This makes them a valuable tool for blandishing future targets of diplomatic vassalization or annexation.

Subsidizing a nation at war with a rival grants Power projection.png power projection.

Subsidize my Love icon
Subsidize 3 different allies at least 50% of their monthly income without running a deficit.

Sell province

A province can be sold to an another nation for a price of 0 to 2,000 ducats at a cost of Prestige.png -10 prestige. Both the buyer and seller must be at peace, and neither can be rivals of the other party. Only one province can change hands in a single transaction. The AI will only offer to sell isolated provinces, particularly if it is unable to core them. When the sell province button is clicked, the province to be sold can be chosen together with the price that will be asked for it.

Factors that influence an AI nation's willingness to buy a province:

Factor Effect
Province is priced above current treasury of buyer -1000
Buyer has no core or claim on province that is of a different culture group -1000
Buyer has no core or claim on province that is of a different religious group -1000
Buyer has no core on province and is currently overextended by any amount -1000
Buyer has no core on province that is part of the Holy Roman Empire -1000
Price -1 for every 1% above above 50% of buyer's treasury
Province is adjacent to buyer +10
Province has the same culture as buyer +10
Province has the same religion as buyer +10
Price -100 to +100 based on development of target province

A province can always be bought as long as the price is affordable if:

  • Buyer is a subject and seller has a core on the province
  • Buyer has core on province

Additionally, it is not possible to sell a province to a colonial subject if the province is not in its colonial region. If the province is particularly undesirable to the buyer, then its base value and associated price modifier will both be halved.

Selling provinces to a vassal is one method of saving administrative power by letting the vassal core the province. It is useful for avoiding overextension in the short term, and exchanges immediate Administrative power.png administrative coring costs for Diplomatic power.png diplomatic annexation costs later. The Cossacks DLC enables giving provinces to vassals directly via the subject interactions interface, making selling provinces to them unnecessary.

As AI nations place a very high priority on core creation, one can delay their research progress in administrative technologies by selling them provinces with a high Administrative power.png coring cost. This can be particularly useful if the next administrative technology would otherwise unlock a troublesome idea group (e.g. AI Portugal's first idea group is always exploration).

Sell ships

Navies can be sold to other nations for a price of 0 to 1000 ducats. If the target nation accepts the proposal, the fleet in question will transfer its allegiance to the buyer. In order to be able to sell ships to a nation, both sides have to be at peace and cannot be rivals of each other. After pressing the button, the fleet that is to be sold can be chosen together with the asking price. When offered to buy a fleet, the AI will want to hold on to a certain ratio of ships (for example, most countries on the Atlantic coast don't want to buy galleys) and will never go above their naval force limit. In order to be able to sell ships, the buyer has to have a fleet within supply range of the target nation. Fleets outside of the receiving country's supply range are not available to sell.

The factors that influence an AI nation's willingness to buy ships:

Factor Effect
Attitude towards proposer Friendly attitude Friendly: +10
Threatened attitude Threatened: -20
Loyal attitude Loyal: +10
Neutral attitude Neutral: -10
Price +50 to -200 depending on treasury of buyer and value of the ships
Buyer wants x fewer ship types -10 per ship of undesired type
Diplomatic reputation +1 per positive point, -1 per negative point

Request to share maps

This allows a nation to ask another nation if they want to share the map of a region. If the nation accepts, the proposer will, at a cost of Prestige.png -15 prestige, discover all provinces that were not yet discovered in the specific region. The nation giving the map will receive Prestige.png 10. Both nations have to be at peace, and can't be rivals of each other. In order to be able confirm the map exchange, the receiving nation has to have a unit stationed in a region adjacent to the specific region.

The factors that influence an AI nation's willingness to share maps are:

Factor Effect
Distance between borders +20 max
Easy +10
Prestige of target nation +0.25 per negative Prestige.png prestige
Rival's interest in region 50 max
Target nation's interest in region -100 max
Target nation is a colonizer -1000
Not the same religious group -20 max
Attitude towards proposer Friendly attitude Friendly: +25
Threatened attitude Threatened: +20
Hostile attitude Hostile: -1000
Unknown attitude Unknown: -50
Nation opinion of proposer +0.25 per positive relation
-0.25 per negative relation
-1000 if opinion -25 or lower
Diplomatic reputation.png Diplomatic reputation Positive: +5 per point
Negative: -5 per point
Trust +1 per point above 50 trust
-2 per point under 50 trust
-1000 if trust 30 or lower

Access actions

Ask for military access

Request military access from the target country, allowing the requester's land armies to pass through its territories. Acceptance will raise the requester's opinion of the host country by +10, while rejection will decrease it by -10. Declaring war on a country that is granting the aggressor military access causes a major -5 hit to stability.

AI nations will only grant military access if they have more positive than negative reasons for doing so. The relevant factors are

Factor Effect
At war with neighboring rival +150
Has alliance +50
Requester army strength +100 max
Attitude towards requester Friendly attitude Friendly: +20
Defensive attitude Defensive: +20
Protective attitude Protective: +20
Threatened attitude Threatened: +20
Neutral attitude Neutral: 0
Unknown attitude Unknown: 0
Hostile attitude Hostile: -100
Rivalry attitude Rivalry: -100
Requester diplomatic reputation Positive: +3 per point
Negative: -3 per point
Nation opinion about requester Positive: +0.2 per point
Negative: -0.5 per point
Trust 0.5 per point

Military access is shared for all participants in a war. For example, if France and Brittany are in a war against Burgundy and France requests military access from Savoy, then Brittany will also have military access to Savoy. Similarly Burgundy, and all of its war allies, would also gain military access to Savoy.

Subject nations always give military access to their overlord. All participants in a war automatically grant military access to their allies, as well as being able to march into their enemies' territory. An army in non-allied land when war is declared, or in territory without military access when war ends, will be exiled.

Offer military access

Offer military access to the target country, allowing their land armies to pass through the requester's territory. Acceptance will raise the target country's opinion of the requester by +10. AI nations are typically uninterested in obtaining military access unless they are the country's ally or subject, or the country is a large and sprawling empire. They will also seek access if they need to travel through a nation to fight in a war. Countries automatically gain military access to countries that grant military access to someone they are at war or allied with.

A country can't revoke access to someone if they, or someone they are at war with, still has troops inside the country's borders.

Ask for fleet basing rights

Acquiring fleet basing rights from a nation will give the following benefits:

  • Naval supply range will now extend from the ports of that nation.
  • Trading range will now extend from the ports of that nation.
  • The requester may dock and repair ships in the ports of that nation.
  • The requester may disembark ground troops in that nation by docking loaded transports at its ports. These land troops will not be exiled, and may move into any adjacent province that they would normally be able to enter.

The cost of purchasing fleeting basing rights is as follows:

  • The base cost is Gold Icon.png 0.1 ducats per month per port, with a minimum of Gold Icon.png 0.5 ducats and maximum of 2.0 ducats. This fee is based on the amount of permanent ports.
  • Non-city colony ports are usable and count toward the fee.
  • Ports that reside in a province which are terra incognita to the receiving country also count toward the fee.
  • Occupied ports only charge a fee if they can be docked at.
  • The fee can be seen in the economy window under Harbor Fees.

Fleet basing rights no longer extend colonial range as in past versions of the game. They can still be used to great advantage by distant fleets however. With El Dorado.png El Dorado active, they are no longer useful to explorers since they no longer take attrition while exploring. Only nations that have diplomatic technology level 2 or higher can grant fleet basing rights.

The following factors will influence an AI nation's decision to grant fleet basing rights:

Factor Effect
Nation is allied to requester +50
Nation opinion of requester Positive: +0.2 per point
Negative: -0.5 per point
Attitude towards requester Friendly attitude Friendly: +20
Defensive attitude Defensive: +20
Protective attitude Protective: +20
Unknown attitude Unknown: 0
Neutral attitude Neutral: -20
Threatened attitude Threatened: -30
Hostile attitude Hostile: -1000
Outraged attitude Outraged: -1000
Rivalry attitude Rivalry: -1000
Trust +0.5 per positive point
Requester diplomatic reputation Positive: +3 per point
Negative: -3 per point
Requester is embargoing nation -1000
Asked nation is embargoing requester -1000

Once fleet basing rights have been obtained, AI nations will generally not revoke them unless there is a drastic change in relationship.

Offer fleet basing rights

Papal actions

Main article: Papacy

Some diplomatic actions require control of the Curia and are also discussed on the papacy page. One of the diplomatic actions, call for crusade, allows the curia controller to call a crusade on a heathen nation. This will give every Christian nation bonuses if they are fighting in a war against the crusade target. The other action, excommunication, will grant every neighbor of the excommunicated ruler of a nation a free casus belli.

Emperor actions

Main article: Holy_Roman_Empire#Powers_of_the_Emperor

The Emperor of the Holy Roman Empire has several special diplomatic options available. These action are each explained in more detail on the Holy Roman Empire page.

Great Power actions

Main article: Great power

The top 8 high-scoring nations receive the Great Power status. For being a great power, you will unlock the following actions:

  • Take on Foreign Debt – Pay off all the loans of the target independent non-great power country. Gives +10 Icon diplomacy relations.png relations bonus for every standard size loan of the target you clear, capped at +200, decaying -2/year. Also grants +5 trust and +2 favours (if The Cossacks.png The Cossacks is enabled). Requires enough money to pay off target’s loans.
  • Influence Nation – Pay 1 year of target income to increase relations and grant +1 All power costs.png monarch points in their weakest category for 10 years in a target non-great power nation. This raises their opinion of the great power by +25 for the 10 years, also gives +5 trust. Going to war with them cancels this bonus.
  • Intervene in War – If there is an ongoing war between three or more great powers but an imbalance in the number of great powers involved on each side, you can make it your business to intervene. For example, if great power England is singlehandedly fighting the great powers of France and Spain, you as a great power Commonwealth can intervene on England's side to balance out the number of great powers involved.
  • Break Alliance – This will force a nation to break its alliance with another. They will accept if the target nation is sufficiently afraid of the player and you will gain a 10-year one-way truce with the nation you forced this upon. It is useful for stripping the war target of pesky roadblocks, because there won't be a truce between the great power and the former ally. The former ally gets a "Forced ally to break alliance" CB against the great power for 10 years. Both the target country and the former ally get a -50 Icon diplomacy relations.png relations modifier with the great power. The target country's trust towards the great power will be reduced by 5. This action is only available with the Rights of Man.png Rights of Man DLC, but not with the Emperor Emperor DLC.

Note: nations who lose the status have access to the above actions for a grace period of 5 years.


These actions are not in the main list, but are also conducted via the Diplomacy panel.

Select rival

The Rival Mechanic added in Wealth of Nations DLC

Rivals are countries that a nation expect to come into conflict with in the future. Rivals are usually very comparable in military and diplomatic power and have interests in the same regions and thus will often clash with each other. A country can have up to three countries set as a rival at the same moment. Rivals may be only selected from countries that are comparable in power; if a rival becomes too weak or too strong it will cease being a valid rival. When selecting possible rivals, the game will take the relative army strength into higher account than the relative navy strength. Relative development and technology levels are also taken into accord. Nations must be relatively near to be eligible rivals, with more powerful countries able to have rivals at greater distance. Setting a nation as a rival will greatly decrease the amount of diplomacy that can be exchanged between the two nations. Rivals rarely accept diplomatic requests from their nemeses. In order to be rivals both countries must have each other discovered. Selecting a rival has the following benefits:

  • A nation is more likely to sign alliances with the enemies of their rivals.
  • +25% Prestige.png prestige from defeating a rival in battle.
  • No Trade efficiency.png trade efficiency penalty from embargoing the rival.
  • +25% spy network build rate against the rival.
  • -33% Diplomatic power.png Diplomatic Power cost for demanding unjustified provinces from the rival in peace deals.

When in the rival selection screen, the nations that are available as rivals and their corresponding opinion of the country and their relative army and navy strength can be seen.

Having a rival and taking actions against it grants Power projection. Not having enough rivals gives a penalty to power projection. The amount of power projection ranges from 0 to a maximum of 100. Power projection provides powerful modifiers to a nation. The percentage modifiers dictated by the amount of power projection are:

Modifier Effect per point of power projection
Global trade power +0.2%
Morale of armies +0.1%
Morale of navies +0.1%
Yearly prestige +0.005
Fort defense +0.1%
Yearly legitimacy +0.005

In addition to these modifiers, the nation will also receive +1 leaders without upkeep at 25 power projection and +1 monarch power per month in all categories when at 50 power projection. As can be seen, power projection should be kept as high as possible to keep receiving its powerful bonuses. The mechanic is detailed in more extensively at the power projection page.

Release subject

This releases a country as a Vassal.png vassal. The released country gets all of their core provinces that are owned by the releasing country, except for the releasing country's capital if applicable. Nations can only be released if at least one owned province is both a core of the nation and has its primary culture. This action can not be done while at war.


  1. See in /Europa Universalis IV/common/static_modifiers/00_static_modifiers.txt (Static modifiers#Base values).