Espionage

In Civilization 4's Beyond the Sword, espionage opens with Writing: an espionage slider and some buildings earn espionage points against each rival, passive missions such as seeing their research unlock as points build up, and spies spend points on missions like stealing technology, sabotage, poisoning water or inciting revolt. Great Spies, counterespionage and a No Espionage option complete the system.

In Civilization 4's Beyond the Sword expansion, espionage becomes available with Writing: an espionage slider joins research and culture, the commerce you put into it (plus points from some buildings) becomes espionage points, and you divide those points among the civilizations you have met. Points piled up against a rival unlock passive missions, such as seeing its research or looking inside its cities, and they pay for the active missions your spies carry out: stealing technology or gold, sabotaging buildings and improvements, poisoning water, fomenting unhappiness, supporting a city revolt, or switching a rival's civics and religion. The manual calls the system "potent 'cloak and dagger' operations", and warns that it is "also expensive" because every point is commerce not spent on research or culture.

Quick facts

Added in	Beyond the Sword
Unlocked by	Writing (Beyond the Sword manual, p. 13)
Points from	The espionage slider, buildings, wonders and Spy specialists
Active missions	12, performed by a Spy, which is used up
Passive missions	5, unlocked by points alone
Spies	Built from Writing; invisible except to other spies; start with Commando
Great Spy	A Great Person added by Beyond the Sword
Espionage Screen	Opened from the button beside the slider
Can be turned off	The No Espionage game option

Espionage points

Espionage points come mostly from commerce. Once you know Writing, the espionage slider appears in the top left of the main screen below the research and culture sliders, and whatever share you give it becomes espionage points each turn (Beyond the Sword manual, p. 13). Some buildings and wonders add points "at no cost to your treasury": the Palace gives +1, and the Courthouse, Castle and Jail give points or point bonuses in Beyond the Sword (p. 45). The Nationhood civic adds +25% to espionage points (p. 47).

Spy specialists add more. They work like other specialists, raising a city's espionage output and its chance of a Great Spy, and the Courthouse, Jail, Intelligence Agency, Security Bureau and Kremlin allow them, per the manual (p. 18). The Intelligence Agency and Security Bureau are buildings new in Beyond the Sword.

The Espionage Screen

The Espionage Screen splits your points between rivals. At first they are divided evenly among every civilization you have met; raising a rival's "Weight" sends it a bigger share, so a weight of 2 against two rivals at 1 gives the first twice as many points, and a weight of 0 gives a rival none (manual, p. 14). GameSpot's preview gave the obvious use: at war with Russia, "you can focus all your espionage points on the Russians" (GameSpot, Jun 22, 2007).

The percentage beside each rival sets your prices. It compares the points you have invested in that rival over the whole game with the points it has invested in you: below 100% you have more and your missions against it are cheaper, above 100% it has more and they cost extra (manual, pp. 14-15). Mission costs also depend on the target city's size, its distance from you, the religions in it and the current era, and they rise as the game goes on.

Spies

Spies carry out the active missions. Any civilization that knows Writing can build them; they are invisible to every unit except other spies, can enter unexplored land and any civilization's territory, and start with the Commando promotion, so they can use enemy roads (manual, p. 15). A spy must begin its turn in the target city or tile to act, can perform one mission per turn, and is used up by the mission; the longer it waits unmoved in a tile, the cheaper missions there become.

Spies are hard to kill. They "cannot be killed normally": an enemy spy can reveal them, which stops them performing missions, and the Kill Spy mission removes them (manual, p. 16). The final patch, 3.19 (Jun 11, 2009), changed one behavior: "Spies no longer interrupt their mission when moving next to an enemy unit". See Units for the rest of the roster.

Before Beyond the Sword, spies came late. In the original game the Spy unit and Scotland Yard both arrived with Communism (GameSpot's guide), which GameSpot's preview said happened "so late in the game that spies were all but useless" (GameSpot, Jun 22, 2007). That preview, of an unfinished build, said espionage would open with Alphabet; the shipped manual says Writing.

Active missions

Mission	Effect
Sabotage Improvement	Destroy an enemy improvement or route
Sabotage Building	Destroy a building in an enemy city
Steal Treasury	Steal 10% to 100% of the rival's treasury
Spread Culture	Increase your culture in a city
Poison Water	Temporarily raise a city's unhealthiness
Foment Unhappiness	Temporarily raise a city's unhappiness
Support City Revolt	Send a city into revolt for one turn, lowering its defenses but not its borders
Steal Technology	Steal a technology
Influence Civics	Switch a rival's civics to one you have adopted
Influence Religion	Switch a rival's State Religion to yours
Perform Counterespionage	Double the cost of enemy missions for 10 turns
Kill Spy	Kill all spies within your spy's sight; only inside your own borders

Source: Beyond the Sword manual, pp. 16-17. The manual gives no fixed point costs, since costs depend on the target and the era; the Espionage Screen shows them, and missions that depend on the spy's exact tile show their cost only once the spy is there.

Patch 3.19 fixed a bug that made culture gained through espionage "100 times lower than intended", so before that patch Spread Culture gave only a hundredth of its intended culture.

Passive missions

Passive missions need no spy, only enough points against a rival, and the threshold rises as that rival builds up points of its own (manual, p. 17):

Can See Demographics: the rival's figures on the Info Screen (F9).
Can See Research: what the rival is researching and how many turns it needs.
City Visibility: the rival's cities are added to your map visibility.
Investigate City: open the rival's city screens by double-clicking their cities.
Spies Cannot Enter Our Borders: that rival's spies cannot enter your territory.

Defending against spies

Defense is mostly points. Investing more against a rival than it invests in you raises its prices, the Spies Cannot Enter Our Borders passive locks its spies out, Perform Counterespionage doubles its mission costs for 10 turns, and Kill Spy clears spies inside your borders. GameSpot's preview added that a spy of your own stationed in a city raises the cost for anyone targeting it, and that courthouses, jails, castles and the new Security Bureau make a hostile spy's job harder (GameSpot, Jun 22, 2007). The War Guide covers using espionage before an attack.

The Great Spy

The Great Spy is the Great Person Beyond the Sword added. The chance of one appearing depends on a city's buildings and its Spy specialists, and various wonders give Great Spy points, per the manual (pp. 18 and 46). A Great Spy is invisible to all other units, including enemy spies and Great Spies, and has four uses:

explore rival territory unseen;
be spent in a rival's city for a "massive" espionage point bonus against that civilization;
join a city as a super specialist, adding science and espionage;
build Scotland Yard, a national wonder only a Great Spy can build (as only a Great Prophet can build a shrine), which adds a large espionage bonus to its city.

See Great People for how Great Person points work.

The No Espionage option

Espionage can be switched off. The final patch's notes (3.19, Jun 11, 2009) describe the "No Espionage option": with it there is "no Free Great Spy from Communism, no espionage-related events", and the "Info screen always shows demographics when espionage is disabled" (in a normal game a rival's figures there are what the Can See Demographics passive mission reveals).

What critics said

GameSpot's review counted espionage among Beyond the Sword's weaker additions: spies "don't provide enough advantages to justify constantly pumping them out", since "they frequently get discovered and captured before they can even get to enemy territory", and it listed "New espionage feature doesn't work all that well" among the negatives (GameSpot, Jul 25, 2007). Years later the system was missed: PC Gamer's review of Civilization 7 regretted losing "sabotaging Wonder production, spy networks, or (Civ 4, how I miss thee) feeling like you're running your own MI5-style spy agency" (PC Gamer, Feb 3, 2025).

Frequently asked questions

How do you get espionage points in Civ 4? In Civilization 4: Beyond the Sword you earn espionage points from the espionage slider (available once you know Writing), from buildings such as the Palace, Courthouse, Castle and Jail, from Spy specialists, and 25% more under the Nationhood civic.

How do you use spies in Civ 4? In Civilization 4: Beyond the Sword you move a spy so that it starts its turn in the target city or tile, then press its Espionage Mission button and choose a mission; the spy is used up, and missions are cheaper the longer it has waited there.

What spy missions are there in Civ 4? Civilization 4: Beyond the Sword has 12 active spy missions, including Steal Technology, Steal Treasury, Sabotage Building, Poison Water, Foment Unhappiness, Support City Revolt, Influence Civics and Influence Religion, plus five passive missions unlocked by points alone.

What does the Great Spy do in Civ 4? In Civilization 4: Beyond the Sword a Great Spy is invisible to all units and can scout rival land, be spent in a rival city for a large espionage point bonus, join a city as a super specialist, or build the Scotland Yard national wonder.

How do you stop enemy spies in Civ 4? In Civilization 4: Beyond the Sword you stop spies by out-investing a rival in espionage points, which unlocks Spies Cannot Enter Our Borders and raises its costs, by using Counterespionage and Kill Spy, and by stationing your own spy in a threatened city.

Can you turn off espionage in Civ 4? Yes: Civilization 4: Beyond the Sword has a No Espionage game option, and patch 3.19 made it also remove the free Great Spy from Communism and espionage-related events.