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This article has been verified for the current PC version (2.7) of the game.

As long as there is at least one empire present that is not Fanatic Pacifist.png Fanatic Pacifist, war is an almost inevitable aspect in any game and can be anything from a small border skirmish to a massive interstellar war of conquest.

Wars are how mid-game and end-game borders are usually drawn.


Casus Belli and WargoalsEdit

In order for an empire to start a war, it needs a Casus Belli – a reason to declare war. Each Casus Belli grants access to at least one type of Wargoal, which represents the purpose of the war. Once a war is declared, the attacked empire has a year to choose its Wargoals.

Casus Belli and Wargoals Requirements Surrender Acceptance Victory Effect Status Quo Effect
Existing claims on the target's systems −10 per system
−100 per colonized system
Loser cedes all systems with Claims to the victor, even if not occupied. All systems occupied by the loser are returned, regardless of Claims. Each side keeps all systems they have occupied if they have claims on them.
  Mutual Defense Resolution 3
Target is not a member of the Galactic Community
Target is at offensive war with a Galactic Community member
0 Loser cedes all systems with Claims to the victor, even if not occupied. All systems occupied by the loser are returned, regardless of Claims. Each side keeps all systems they have occupied if they have claims on them.
  Make Tributary
  Make Subsidiary
Demand Subject Status diplomatic action was refused −100 Loser becomes a subject of the victor, along with all its vassals (if any). If the empire is part of a Federation, it will leave it. All systems fully occupied by the attacker will be turned into a subject of the attacker.
  Establish Hegemony
President of a level 3   Hegemony federation −100 Loser becomes a member of the victor's   Hegemony All systems fully occupied by the attacker will be turned into a member of the attacker's   Hegemony.
  Rivalry −50 Victor gains 100   Influence. Loser loses all of its   Influence, gains -33%   Monthly Influence Gain and -10%   Happiness for 10 years. If the loser had the   Supremacist Diplomatic Stance Policy it is changed to   Belligerent. None
  Impose Ideology
War Philosophy policy set to Liberation Wars
Neither empire is a   Gestalt Consciousness
−100 Loser is forced to shift ethics towards those of the victor and will leave a Federation if it's part of one. Its ruler is also replaced. All systems fully occupied by the attacker will be turned into an empire with the attacker's ethics.
  Barbaric Despoilers civic −25 Loser loses 500   Energy and 500   Minerals for every 3 planets they own, rounded up, and capped at 60 planets, for a maximum of 10,000   Minerals and   Energy gained. Victor will then gain those resources even if the loser didn't have enough. Loser gets -20% reduced    production for 10 years. Each side keeps all systems they have occupied if they have claims on them.
  Expel Corporation
No Commercial Pact or Federation present
Corporate empire has at least one Branch Office on the other's planets
−50 If the Corporate empire loses it closes all Branch Offices on the attacker's planets and the attacker gains 1000   Energy per Branch Office. If the Corporate empire wins the attacker becomes a   Subsidiary of the Corporate empire. Corporate empire closes all Branch Offices on the attacker's planets. Corporate empire gains 1000   Energy per Branch Office.
Hostile Takeover
  Hostile Takeover
Both empires have   Corporate authority
Target has at least one Branch Office
−75 All Branch Offices are transferred to the victor. If part of a Federation Branch Offices on other members' planets are kept. None
  Bring Into Fold
  Scion origin −100 If the Scion wins the loser becomes a subject of the Scion's overlord All systems fully occupied by the Scion will be turned into a subject of the Scion's overlord.
  Stop Atrocities
  Outlaw AI
  Cleanse Holy Worlds
  Decontaminate Border Territories
Only available to Fallen Empires
Either the Fallen Empire's demand was refused or they were rivaled
0 The refused demands are enforced. If the defeated empire is not a   Gestalt Consciousness, the ruler will be killed. Includes Animosity effects. None
Claim the Galatron
  Take Galatron
Target empire has the Galatron Relic −40 Victor keeps (or acquires) the Galatron Relic and gains 100   Influence. Includes Animosity effects. None

Paired WargoalsEdit

The following Wargoals are paired together. If an empire starts a war with either of the paired wargoals the defender will automatically use the other wargoal and cannot pick another one.

Paired Wargoals with −1000 surrender acceptance lead to a Total War. In Total Wars all occupied systems automatically change ownership. Their new owner will be the participant with the highest claim count on it or the occupier if none of his allies claim this system.

Casus Belli and Wargoal 1 Casus Belli and Wargoal 2 Requirements Surrender Acceptance Victory Effect Status Quo Effect
  Assert Overlordship
  Subject and Overlord 0 If the subject wins it becomes independent and the former Overlord loses all Claims on the former subject's systems. The subject becomes independent and the former Overlord gains Claims on the former subject's systems.
  Leave Hegemony
  Assert Hegemony
  President refused member to leave Federation 0 If the attacker wins it leaves the Federation and the President loses all Claims on the former member's systems.
If the President wins both empires gain a temporary -20   Opinion towards each other.
The attacker leaves the Federation and the President gains Claims on the former member's systems.
  End Threat
Fallen Empire −1000 (Total War) Victory can only be achieved by conquering all colonized systems of the opposition, ending the opposing empire. If a defeated empire had Starbases in uncolonized systems that were not conquered they are removed, making the territory neutral again. Each side keeps all conquered systems.
  Fanatic Purifiers or   Determined Exterminator
  Devouring Swarm
  Driven Assimilator
Stop Colossus
  Stop Colossus
Either empire has a Colossus −1000 (Total War)
Preemptive War
  Preemptive War
  End Threat
  Mutual Defense Resolution 5 is passed
One empire is not a member of Galactic Community
−1000 (Total War)
  War in Heaven
  War in Heaven
Awakened Empire −1000 (Total War)
  Machine Uprising
  Machine Uprising
Creator empire and Machine Uprising −1000 (Total War)


While Casus Belli and Wargoals represent the purpose of a war, claims represent territorial ambitions—the systems which will be controlled by the victor. Which systems can be claimed depends on an empire's War Philosophy policy, with the Unrestricted Warfare philosophy allowing for the claiming of any system not owned by a fellow Federation member. It is possible to claim the same system multiple times to gain a stronger claim on it, which can outbid the competing claims of allies when going to war together. If multiple empires have equal-strength claims on a system the oldest claim is considered the strongest. In general claims are expensive in the early game and become less so later on to allow for more decisive wars to be fought. Claims cannot be rescinded while at war.

Claims cost   influence, the base cost being 50, modified by the following:

  • +25 per hyperlane distance from owned territory
  • +25 if the system has at least a lvl 1 Starbase (i.e. not just an Outpost)
  • +25 if the system is colonized
  • +100% during offensive war
  • –10%   Expansionist Overtures agenda
  • –10%   Belligerent or   Supremacist policy
  • –10%   Interstellar Campaigns technology
  • –10%   Galactic Campaigns technology
  • –10%   Nationalistic Zeal civic
  • –10%   Militarist
  • –20%   Fanatic Militarist
  • –20%   Interstellar Dominion ascension perk
  • –20%   Great Khan's Throne relic
  • –20%   Rivalry (multiplicative, after other multipliers)

During defensive wars, claims can be made for any system by the defender, regardless of the War Philosophy policy. Any system lost by any side during a conquest war or total war will give the former owner a claim on it.

Winning war with any non-conquest wargoals will always enforce all claims made by the winning side empires first, regardless of whether these systems were occupied. So for example, winning war with subjugation wargoal against other empire(s) will make it (and any of its allies) lose all systems that have claims on them, including ones made by the now-overlord empire, and only then become a vassal, with territory reduced like that and free claims of strength 10 on all lost systems.

Federation WarfareEdit

The Federation is the more serious counterpart of the Defensive pact and the inviting attackers mechanic. While it does offer a unique amount of defensive cooperation, builds trust and allows military cooperation using the federation fleet, establishing a conquest strategy can be made very difficult because of the need for unanimous consent of the members to declare war, and each member's expectation of a fair share of spoils from each war. The empire that wishes to declare war can ask the other federation members for their war goals by using the "Suggest Demands" button. However, AI empires will be very hesitant to declare war on empires that are much stronger than them or have very powerful allies. In that case, the "Suggest Demands" button will not give any results.

One exception to this are wars of liberation or to a lesser extent vassalization: usually AI will agree to a liberation war even if all the war goals are assigned to the player. The resulting splinter empire could then be vassalized and later integrated by the player.

In case a federation member is attacked, all allies automatically join the war as defenders without need for a further declaration of war. In this case, the member being attacked has a free hand in choosing federation war goals, which might be all in its own favor.

War ExhaustionEdit

War Exhaustion goes from 0% to 100%, and measures the total weariness and attrition suffered by all empires on one side in a war. War Exhaustion goes up from suffering losses during Space and Ground Warfare, destruction of planets (either from Colossus weapons or   Armageddon Bombardment), and a passive accumulation over time called Attrition. When a side's War Exhaustion hits 100% they can be forced into a Status Quo peace after 24 months. The speed at which War Exhaustion accumulates is influenced by factors such as ethics, traditions, technology and the amount of claims being pressed - an empire that is fighting to hold onto a handful of border systems will tire faster in a costly conflict than one whose very independence is being threatened. War Exhaustion also means that an Empire that is losing a war can still fight to minimize their territorial losses by inflicting high War Exhaustion on the enemy.

War Exhaust Gain can be reduced by the following:

Source Reduction
  Media Conglomerate civic -5%
  Nationalistic Zeal civic -10%
  Interstellar Campaigns technology -10%
  Galactic Campaigns technology -10%
  Belligerent diplomatic stance -10%
  Supremacist diplomatic stance -20%
  Gestalt Consciousness ethic -20%
  Rules of War resolution 2 -5%
  Rules of War resolution 3 -10%
  Rules of War resolution 4 -15%
  Rules of War resolution 5 -20%

Ending WarsEdit

Wars can end in two ways: With the surrender of either side or with a negotiated Status Quo peace.

Surrender means that the victor's Wargoal is enforced, any claims the winning side has on the losing side are automatically ceded regardless of occupation status and the defeated empire is forced to keep borders open towards the attacker for 10 years. All wars except those of independence have a negative surrender acceptance, which are countered by factors such as Relative Navy Strength (up to +50), War Exhaustion (up to +100) and Occupation Percentage (up to +100). If an empire and all of its allies (if any) has lost control of all of its systems and/or planets during the war, then a surrender will occur automatically.

Status Quo means that the war has reached a point where neither side is able to score a decisive victory against the other or all wargoals have been achieved decisively before any major battles took place, and both sides agree to cease hostilities and settle for whatever gains or losses they have acquired/suffered. Under a Status Quo peace, all fully occupied systems claimed by a belligerent empire are ceded to the belligerent with the strongest Claim. In the case of a tie, whoever has the oldest claim on the system is considered the stronger claimant. In addition both sides must keep their borders open towards each other for 10 years. Since AI won't surrender to a Total War, they can end only in Status Quo or the destruction of one empire. Status Quo can be enforced by any side as soon as 24 months passed since the opposing side reached 100% War Exhaustion and if both sides reach 100% War Exhaustion the Status Quo is enforced automatically after 24 months.

War NamesEdit

Wars will always be named after the attacker and the defender, followed by one of the following names depending on the wargoal:

Name Wargoal Other requirements
War Any Offensive war against a Fallen Empire
  • Federation War
  • Galactic War
  • Great War
  • War of the Alliances
Any War between two Federations
  • Annexation Attempt
  • Territorial Invasion
  • War of Aggression
  • War of Conquest
  • War of Beliefs
  • War of Ideologies
  • War of Philosophies
Impose Ideology
  • Border War
  • Confrontation
  • War of Humiliation
  • War of Rivalry
Humiliate Regular empire
Punitive Expedition Humiliate Fallen Empire
Anti AI Police Action Outlaw AI
Buffer Zone Creation Decontaminate Border Territories
Holy Purge Cleanse Holy Worlds
Moral Intervention Stop Atrocities
  • Freedom Struggle
  • Independence War
  • Secessionist War
  • War of Independence
  • War of Liberation
  • Servitude Campaign
  • War of Obedience
  • War of Overlordship
  • War of Subjugation
Tributary War Make Tributary Not   Corporate authority
Enforced Sponsorship Make Tributary   Corporate authority
The War In Heaven War in Heaven
  • Intervention War
  • Preemptive Action
  • Preventative War
  • Self Protection War
End Threat
  • War of Cleansing
  • Xeno Filth Removal
  • Xeno Purification
Cleansing   Fanatic Purifiers civic
  • Extermination Campaign
  • Organic Disinfection Program
  • Organic Euthanization War
Cleansing   Determined Exterminator civic
  • Absorption War
  • Biomass Accumulation
  • Great Gorging
Machine Uprising Machine Uprising
Subsidiary Acquisition Make Subsidiary
Hostile Takeover Hostile Takeover
  • Embargo War
  • Expulsion War
  • War of Expropriation
Expel Corporation
War for the Galatron Take Galatron
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