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Revision as of 10:48, 30 October 2016 by Philadelphus (talk | contribs) (Passive Benefits: Rewrote to make it more consistent and clear about which benefits came from which DLCs.)
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Espionage idea group.png Espionage
Spy network construction.png Efficient Spies
+50% Spy network construction
−10% Advisor costs

Diplomat.png Agent Training

+1 Diplomat

Foreign spy detection.png Vetting

+33% Foreign spy detection

Aggressive expansion impact.png State Propaganda

−20% Aggressive expansion impact

May fabricate claims for subjects.png Claim Fabrication

May fabricate claims for subjects
−25% Cost to fabricate claims

Embargo efficiency.png Privateers

+25% Embargo efficiency
+33% Privateer efficiency

Yearly corruption.png Audit Checks

−0.10 Yearly corruption

Idea bonus.png Bonus:

+50% Rebel support efficiency

Associated events: Espionage idea group events

Espionage is a way to weaken enemies without actually going to war. In Europa Universalis 4 espionage works somewhat differently than EU3: there are no longer any spy agents, but covert actions are present. Rather than spies, Diplomat.png diplomats perform espionage. Espionage has an associated idea group in the diplomatic group of ideas which enhances several espionage aspects. As the game progresses more covert actions become available for use by progressing in Diplomatic tech.png diplomatic technology.

Spy efficiency

Spy network construction

Covert actions are executed by sending a Diplomat.png diplomat to construct a spy network in a foreign nation. As the spy networks' size grows, more costly covert actions can be executed in the target nation. A spy network which isn't being actively maintained by a diplomat will slowly decay over time. As long as the aggressor has a big enough spy network it is possible, if so desired, to perform a succession of covert actions on the target; all of which will be instantaneous and successful upon execution, along with most of the actions also having the effects lasting for a duration of Time Icon.png 5 years.

It is important to note that it's not possible to construct a spy network in a subject nation. The aggressor has to build the spy network in the overlord's nation instead. That one network can then be used to execute covert actions in the overlord's and any of its subjects nations.

Spy network construction has a base construction speed of 1.50 per month modified by distance and the following:

Spy network construction.png Triggers
  • Advisor Spymaster.png Spymaster advisor
  • Target is a Rivalry attitude Rival
+25% Ruler has personality “Intricate Webweaver”
+20% Trading in Spices.png Spices
-50% Corruption.png Corruption (at 100%)

Spy network construction.png Traditions Ideas Bonuses Policies
  • Espionage idea 1: Efficient Spies
  • Daimyo traditions
  • Ito traditions
  • Ardabili idea 5: Religious War
  • Aztec idea 7: Pochtecayotl
  • Hosokawa idea 6: Yamabushi
  • Kitabatake idea 6: Iga-Ryu
  • Kuban idea 4: Usurpation of the Chiefs
  • Lunda idea 7: Lord of the Vipers
  • Munster idea 7: Enemies Within
  • Pattani idea 3: Smuggling Networks
  • Samtskhe idea 2: Proactive Diplomacy
  • Tokugawa idea 2: Strengthen the Sekisho Network
  • Transoxianian idea 3: Adept Diplomacy
  • Trebizondian idea 7: Greek Scholars Abroad
  • Uesugi idea 5: Nokizaru
  • Frankfurter idea 4: Frankfurter Postzeitung
  • Italian idea 6: Italian Diplomacy
  • Sligonian idea 4: A Different Way
  • Takeda idea 3: Information Network
  • Ulster idea 6: The Defenders
  • Espionage-Offensive: The Black Chamber Act

Passive Benefits

Having a spy network in a foreign nation grants several passive benefits for the country creating the spy network when certain DLCs are enabled. The benefits scale with the networks' size and at a 100 spy network will apply:

  • Siege ability.png+20% Siege ability
  • Aggressive expansion impact.png-10% Aggressive expansion impact (in that nation)
  • Technology.png-30% Technology costs
    • The applied reduction is -5% for each tech level the target is ahead in a certain tech field compared to the nation building the spy network (in case of multiple same-field reductions only the highest is applied).
    • This benefit is unlocked at Diplomatic tech.png Diplomatic technology 9.

Foreign spy detection

Foreign spy detection determines the chances of discovering actively built spy networks in the nation.

Foreign spy detection has a base efficiency of 100% modified by the following:

Foreign spy detection.png Modifier
+25% Trading in Tobacco.png Tobacco
+25% Ruler has personality “Secretive”
  • Per Icon stability.png Stability Positive point
  • During Parliament.png Treason Act (10 years)
+10% Prestige.png Prestige (at 100%)
-10% Prestige.png Prestige (at -100%)
-15% Per Icon stability.png Stability Negative point
-25% Corruption.png Corruption (at 100%)
-25% Ruler has personality “Loose Lips”
Foreign spy detection.png Traditions Ideas Bonuses Policies
  • Espionage idea 3: Vetting
  • Cascadian idea 4: Settling the Boundaries
  • Three Leagues idea 2: The League of God's House
  • Dahomey idea 4: Lagredis
  • Venetian idea 4: Found the State Inquisition
  • Chimu idea 4: Watchfulness of the Moon
  • Italian idea 3: Italian Aristocracy
  • Ormond idea 5: Irish Rivalries
  • Defensive-Administrative: The Spy Discovery Act
  • Espionage-Administrative: The Royal Commission Act
  • Espionage-Expansion: The Loyalty Act
  • Exploration-Defensive: The Naval Secrecy Act
  • Religious-Espionage: Enforce Religious Law
  • Creek traditions
  • Sligonian idea 4: A Different Way
  • Ulster idea 6: The Defenders
  • Takeda idea 3: Information Network


Counter-espionage is performed by sending a Diplomat.png diplomat to a foreign nation with the intention of hunting down spies. As long as the diplomat continues the action, the aggressor nation gets Foreign spy detection.png+33% Foreign spy detection against that particular nation in addition to applying further Spy network construction.png –50% and slowing their network construction. This effectively hinders others' efforts to execute covert actions if not outright stopping them.

Discovery chance

Spy network construction has a Discovery chance upon reaching size 25; meaning, an aggressor can fabricate a single claim or generate a trade conflict CB without risking the chance of being discovered if the network size is smaller than 25.

The Discovery chance is calculated as the sum of the Yearly discovery chance, which has a base of 25%[1] (or a 2.083% Monthly discovery chance), and the difference between the defending nation's Foreign spy detection and the attacker's Spy network construction. While there are modifiers reducing (or increasing) the discovery chance, it cannot be reduced below ~0.06% per month.

A nation which has been discovered building a spy network will have it's diplomat sent back and restricted from further developing the spy network for Time Icon.png 3 months[2]. In addition, the size of the spy network will be reduced to the nearest 25 milestone. I.E., being discovered at spy network 70 will reduce the spy network to 50.

Covert actions

  • All actions are instantaneous and successful upon execution; Most actions have a duration of Time Icon.png 5 years.
  • Actions can still be executed even if a diplomat can't further build a spy network (due to discovery).
  • Same type (covert action) effects are not additive; I.E., Agitate for Liberty effects will apply only once per nation even if 2 or more aggressor nations executed it on the target.
Action Cost Diplomatic tech.png Requirements Effects Notes DLC
Fabricate Claim 20
  • War.png Not at war with target
  • Yes Has a shared border (by land or sea-zone) with target
Gain a claim (conquest CB) on a target's province for Time Icon.png 25 years Claim duration are automatically extended to account for war or truce times with the target
Justify Trade Conflict 10 In the same trade node:
  • Merchants.png Has a merchant present
  • Trade power.png Has at least 10% trade power
  • Trade power.png Target has at least 20% trade power
Gain a trade conflict CB against the target for Time Icon.png 2 years Often the best way to get a CB on a distant nation, however, the CB does not allow to take land, revoke cores, or release vassals/nations in a peace Wealth of Nations.png
Support Rebels 60 National unrest.png Target has any rebel faction with above 0 unrest Rebel support efficiency.png+10% Revolt progression chance per month for the selected rebel faction This action also requires a one-time monetary payment proportional to the supported faction's size at the time the action is undertaken
Steal Maps 50 6
  • Yes Target has discovered a region unknown to us adjacent to a region known to us
  • Yes Has a unit in a known region adjacent to said unknown region
Steal target's maps of a region Mare Nostrum.png
Slander Merchants 70 12
Trade power.png −10% Global trade power
Mare Nostrum.png
Sabotage Recruitment 80 15
Manpower recovery speed.png −20% Manpower recovery speed
Sailor recovery speed.png −20% Sailor recovery speed
Mare Nostrum.png
Sow Discontent 80 18
National unrest.png +2 National unrest
Legitimacy.png −1 Yearly legitimacy
Republican tradition.png −0.2 Yearly republican tradition
Devotion.png −1 Yearly devotion
Horde unity −1 Yearly horde unity
Meritocracy.png −0.5 Yearly meritocracy
Target gets higher stability costs and a higher revolt chance
Sabotage Reputation 60 21
Diplomatic reputation.png −3 Diplomatic reputation
Target has a higher difficulty to recover its reputation from recent expansions or betrayals, make alliances or other diplomatic agreements
Corrupt Officials 25 24
Yearly corruption +0.1 Yearly corruption
Mare Nostrum.png
Agitate for Liberty 90 27 Yes Target is a subject Liberty desire.png+25% Liberty desire The Cossacks.png
Infiltrate Administration 40 30 Lift the Fog of War from the target nation

Cost modifiers

Fabricate claim

Main article: Claim

Claims that are granted by missions behave just like fabricated claims, although their duration may be different depending on mission parameters.

Besides providing a conquest CB, claimed provinces have the following benefits when conquered:

  • Core-creation cost.png −10% Core-creation cost
  • Local autonomy.png −10% Local autonomy

Fabricate claim cost is modified by the following:

Cost to fabricate claims.png Traditions Ideas Bonuses Policies
  • Munster traditions
  • Naxian traditions
  • Espionage idea 5: Claim Fabrication
  • Chiba idea 3: Coalition With Kamakura Kubo
  • Cypriot idea 1: King of Jerusalem
  • Imagawa idea 1: Claim to the Shogunate
  • Isshiki idea 4: Reclaim Old Territories
  • Lorraine idea 3: Lotharingia
  • Northumbrian idea 2: The Memory of Northumbrian Hegemony
  • Papal idea 4: Donation of Constantine
  • Polotskian idea 1: Legacy of the Werewolf Prince
  • Provençal idea 1: Memory of Angevin Claims
  • Yaroslavlyian idea 1: Between Hammer and Anvil
  • Nizhny Novgorod ambition
  • Thomondian ambition
  • Brandenburg traditions
  • Saxe-Lauenburg idea 1: The Partition of Saxony

Decisions and events:

Cost to fabricate claims.png Event modifier Trigger Time Icon.png Duration
−25% Aphra Behn Flag of England Flag of Great Britain Women in History event: “Aphra Behn
Option: ‘Keep this a close secret!’
for 20 years
Emperor condemns Tuscany Flag of Tuscany Tuscan event: “The Emperor Condemns Tuscany's Elevation
Option: ‘The Emperor will not stand in the way of God's will.’
for 20 years
+50% Limited Claim Fabrication Diplomatic ideas event: “Incompetent Diplomats
Option: ‘They are of noble blood though...’
for 5 years

Note: Inter Caetera the third national idea of Flag of Castile Castile / Flag of Spain Spain allows the use of fabricate claim on colonies which normally wouldn't be in reach of that action. This allows Castile/Spain to target colonies both inland and distant overseas, making any colony in the world a potential target (this can no longer be used once the colony turns into a city).

Justify trade conflict

Justify trade conflict cost is modified by the following:

Justify trade conflict cost.png Traditions Ideas Bonuses Policies
  • Genoese idea 1: Reuniting the Nation
  • Hanseatic idea 4: Reformed Hanstag
  • Venetian idea 6: Defend the Law

Support rebels

Main article: Rebellion#Support for rebels

Supported rebels will be treated as allied units, regardless of when the action began. If the rebel faction has spawned rebel units in multiple countries, then all those units will be treated as allies once support is given to that faction anywhere.

Allied rebels that are sieging a province that is an objective of theirs will not transfer leadership of the siege to the player in a war. If allied rebels cannot complete their objectives because the province they are trying to occupy is under another nation's control, they will instead wander the countryside and may engage enemy units.

Support rebels efficiency is modified by the following:

Rebel support efficiency.png Traditions Ideas Bonuses Policies
  • Full Espionage
  • Espionage-Economic: The Foreign Support Act
  • Samtskhe traditions
  • Piratical idea 7: Life of Liberty
  • Humanist-Espionage: Cultural Understanding
  • Leinster idea 3: The Subject of My Enemy is My Friend
  • Palatinate idea 3: Center of Reformation in Southern Germany


Networking icon
Have 100 point spy networks in 3 rival nations.
Just Resting In My Account icon
Just Resting In My Account
Corrupt the officials in a rival country.
Time Bandit icon
Time Bandit
Successfully steal a map from another nation.


  1. See in /Europa Universalis IV/common/defines.lua: BASE_SPY_DISCOVERY_CHANCE = 0.25,
  2. See in /Europa Universalis IV/common/defines.lua: SPY_DISCOVERY_COOLDOWN_MONTHS = 3,