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The Spy underwent significant changes from Warlords to Beyond the Sword. The original Spy was a "National Unit" and therefore only 4 could exist for each player at any given time.

Spy old (Civ4)

The Spy in modern eras.


Use the Spy to explore enemy territory and perform Espionage Missions.

Civilopedia entry (pre-BTS)[]

Spies are special "invisible" units which can sneak around the map and have a variety of special abilities. Spies also function defensively by increasing the odds of an enemy spy being exposed if it performs a mission in a nearby tiles.

Constructing Spies[]

Spies may be built only in a city with the Scotland Yard national wonder.


Spy units are invisible. They cannot be seen, attacked, or otherwise interacted with.


Spies move like other units, except that they do not cause an automatic declaration of war when crossing foreign Borders.

Spy Missions[]

Spies may perform a variety of missions, some of which are automatically fatal and others of which contain a chance of destruction. Spies can perform these missions anywhere on the map, including in territory belonging to allies or to civilizations you are at war with.


Being invisible, spies can move through neutral, friendly and enemy territory without risk.

Investigate City[]

Upon entering a foreign city, a spy may look at its City Screen and thus know important things, like what defenses the city contains, what it is currently building, and so forth.

Destroy Production[]

A spy performs this in a city. If successful, the spy survives and the city loses half of the production points towards whatever it is currently producing. For example, this can be quite devastating if the city is just a couple of turns from completing construction of a wonder. If the mission is unsuccessful, no production is lost and the spy is destroyed.

Sabotage Improvement[]

This is performed on any space containing an Improvement. If successful, the improvement is destroyed and the spy survives. If unsuccessful, the spy is destroyed and the improvement survives.

Steal Plans[]

This mission has a much higher chance of success in one of a civilization's "centers of government" - a city containing the Palace, Forbidden Palace or Versailles wonder. If successful, the spy survives and you get to see everything that is visible to the foreign civilization. This includes everything in its territory or within sight of its units and borders. If unsuccessful, the spy dies and you don't get to see anything.

Determining Success or Failure of a Spy Mission[]

The odds of success or failure of a spy's mission depend upon the number of units the other player has in the space the mission takes place. If a space is unoccupied, the chances of success are quite high. The chances of detection and failure increase with each unit in the target space. Further, nearby enemy spies significantly increase the chances of being caught.

Diplomatic Effects of Missions[]

If a mission is successful, the target civilization will not know who performed the mission; thus that civilization's opinion of you will not change. If the mission is a failure, the target civilization will know exactly who is responsible for the outrage and will adjust its opinion of you appropriately. It is quite possible for a failed spy mission to cause the victim civilization to declare war on your civilization!


  • The pre-BtS Spy appears as a woman wearing a biker outfit.

See also[]

  • Spy in other games
Civilization IV Units [edit]
Land Anti-TankB Archer (BowmanB Skirmisher) Artillery Axeman (Dog SoldierB Phalanx VultureB) Cannon Catapult (HwachaW) Cavalry (Cossack) Chariot (Immortal War Chariot) Crossbowman (Cho-Ko-Nu) CuirassierB (Conquistador) Explorer Grenadier Gunship Horse Archer (Keshik Numidian CavalryW) Infantry Knight (Camel Archer CataphractB) Longbowman Maceman (BerserkerW Samurai) Machine Gun Marine (Navy SEAL) Mechanized Infantry Mobile ArtilleryB Mobile SAMB Modern Armor Musketman (JanissaryW Musketeer Oromo WarriorB) ParatrooperB Pikeman (LandsknechtB) Rifleman (Redcoat) SAM Infantry Scout Spearman (HolkanB ImpiW) Swordsman (Gallic WarriorW Jaguar Praetorian) Tank (Panzer) TrebuchetW War Elephant (Ballista ElephantB) Warrior (Quechua)
Naval Attack SubmarineB Battleship Caravel (CarrackB) Carrier Destroyer Frigate Galleon (East IndiamanB) Galley Ironclad Missile CruiserB PrivateerB Ship of the LineB Stealth DestroyerB Submarine Transport TriremeW
Air AirshipB Bomber Fighter Guided MissileB ICBM Jet Fighter Stealth Bomber Tactical NukeB
Civilian Corporate ExecutiveB Missionary Settler Spy Work Boat Worker (Fast Worker)
Great People Great Artist Great Engineer Great GeneralW Great Merchant Great Prophet Great Scientist Great SpyB
W Added in Warlords B Added in Beyond the Sword