This article has been verified for the current console
version (3.0) of the game.
As long as there is at least one empire present that is not
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 wargoals[edit source]
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
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Requirements
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Surrender acceptance
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Victory effect
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Status quo effect
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Claim
Conquer
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Existing claims on the target's systems
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- −10 per system
- −100 per colonized system
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Loser cedes all systems with claims to the victor, even if not occupied. All systems occupied by the loser are returned, regardless of claims.
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Each side keeps all systems they have fully occupied if they have claims on them.
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Counterattack
Counterattack
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Mutual Defense resolution 3
- Target is not a member of the Galactic Community
- Target is at offensive war with a Galactic Community member
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0
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Loser cedes all systems with claims to the victor, even if not occupied. All systems occupied by the loser are returned, regardless of claims.
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Each side keeps all systems they have fully occupied if they have claims on them.
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Subjugation
Vassalize
Make Tributary
Make Subsidiary
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Demand Subject Status diplomatic action was refused
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−100
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Loser becomes a subject of the victor, along with all its vassals (if any). If the empire is part of a federation, they will leave it.
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If the attacker did not fully occupy any systems with inhabited planets of the defender, all occupied systems will be returned to the defender. If the attacker fully occupied at least one system with an inhabited planet, all systems fully occupied by the attacker will be turned into a new empire that is a subject of the attacker. However, the defender always gets to keep their empire capital, even if it was successfully occupied.
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Animosity
Humiliate
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Rivalry
- Must not have access to Ideology CB
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−50
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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.
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Each side keeps all systems they have occupied if they have claims on them.
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Ideology
Impose Ideology
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- War philosophy policy set to Liberation Wars
- Target is not a
Gestalt Consciousness
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−100
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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.
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If the attacker did not fully occupy any systems with inhabited planets of the defender, all occupied systems will be returned to the defender. If the attacker fully occupied at least one system with an inhabited planet, all systems fully occupied by the attacker will be turned into a new empire with the attacker's ethics. However, the defender always gets to keep their empire capital, even if it was successfully occupied.
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Punishment
Humiliate
Stop Atrocities
Outlaw AI
Cleanse Holy Worlds
Decontaminate Border Territories
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- Only available to fallen empires
- Either the fallen empire's demand was refused or they were rivaled
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0
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The refused demands are enforced. If the losing empire is not a Gestalt Consciousness, its ruler will also be assassinated by the winning fallen empire, unless they are the Ancient Caretakers. Includes Animosity effects.
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None
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Despoliation
Plunder
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Barbaric Despoilers civic
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−25
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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 10,000 energy. Victor will then gain those resources even if the loser didn't have enough. Loser gets  for 10 years.
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Each side keeps all systems they have occupied if they have claims on them.
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Expropriation
Expel Corporation
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- No commercial pact or federation present
Corporate empire has at least one branch office on the other's planets
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−50
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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.
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Corporate empire closes all branch offices on the attacker's planets. Corporate empire gains 1000 energy per branch office.
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Hostile Takeover
Seize Assets
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- Both empires have
Corporate authority
- Target has at least one branch office
 Criminal Heritage civic
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−75
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All branch offices on planets whose owners have a commercial pact, or federation, with victor are transferred to the victor. If loser is part of a federation, branch offices on other members' planets are kept.
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None
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Claim the Galatron
Take Galatron
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- Target empire has the Galatron relic
 Driven Assimilator civic
   Genocidal
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−40
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Victor keeps (or acquires) the Galatron relic and gains 100 influence. Includes Animosity effects.
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None
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Hegemon
Establish Hegemony
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President of a level 3 Hegemony federation
- Target is not in federation
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−100
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Loser becomes a member of the victor's Hegemony
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All systems fully occupied by the attacker will be turned into a member of the attacker's Hegemony.
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Scion
Bring Into Fold
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Scion origin
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−100
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Loser becomes a subject of the Scion's overlord. If the empire is part of a federation, they will leave it.
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All systems fully occupied by the Scion will be turned into a subject of the Scion's overlord.
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Imposed Inclusion
Bring Into Fold
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Become the Crisis ascension perk
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−100
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Loser becomes a vassal of the attacker. If the empire is part of a federation, they will leave it.
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All systems fully occupied by the crisis empire will be turned into a vassal of the attacker.
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Trial of Advancement
Council Seat
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- Target is a member of the Imperial Council
By Trial of Advancement resolution
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−100
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The victor replaces the loser in the Imperial Council.
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None
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Imperial Crusade
Force Into Imperium
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Imperial Crusade resolution
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−100
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Loser joins the Galactic Imperium. If the empire is part of a federation, they will leave it.
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All systems fully occupied by members of the Galactic Imperium will be turned into a member of the Galactic Imperium.
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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
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Casus belli and wargoal 2
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Requirements
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Surrender acceptance
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Victory effect
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Status quo effect
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Subject
Independence
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Subject
Assert Overlordship
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Subject and overlord
Subject not in a federation with overlord
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0
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If the subject wins, it becomes independent and the former overlord loses all claims on the former subject's systems.
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The subject becomes independent and the former overlord gains claims on the former subject's systems.
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Secession
Leave Hegemony
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Secession
Assert Hegemony
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President refused member to leave federation
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0
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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.
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The attacker leaves the federation and the president gains claims on the former member's systems.
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Containment
End Threat
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Subjugation
Assimilation
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Awakened Empire
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−1000 (Total War)
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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.
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Each side keeps all conquered systems.
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Purification
Cleansing
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Fanatic Purifiers or Determined Exterminator
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Hunger
Absorption
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Devouring Swarm
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Sublimation
Assimilation
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Driven Assimilator
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Existential Expulsion
Wipe Them Out
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Become the Crisis ascension perk
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Colossus
Colossus
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Stop Colossus
Stop Colossus
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Either empire has a Colossus
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Preemptive War
Preemptive War
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Self-Defense
End Threat
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Mutual Defense resolution 5
One empire is not a member of the Galactic Community
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Crisis War
Crisis War
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Crisis War
Crisis War
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Declare Crisis resolution
 Repeal Crisis resolution
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Event
War in Heaven
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Event
War in Heaven
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Awakened Empire
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Event
Machine Uprising
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Event
Machine Uprising
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Creator empire and Machine Uprising
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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%
Martial Alliance level 2 perk
- –10%
Militarist
- –20%
Fanatic Militarist
- –20%
Interstellar Dominion ascension perk
- –20%
Great Khan's Throne relic
- –20%
Rivalry (multiplicative, after other multipliers)
If the modifier reaches a total of –100%, claims then cost 0
influence.
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.
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 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 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
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Reduction
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Media Conglomerate civic
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−5%
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Nationalistic Zeal civic
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−10%
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Interstellar Campaigns technology
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−10%
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Galactic Campaigns technology
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−10%
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Belligerent diplomatic stance
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−10%
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Supremacist diplomatic stance
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−20%
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Gestalt Consciousness ethic
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−20%
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Rules of War resolution 2
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−5%
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Rules of War resolution 3
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−10%
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Rules of War resolution 4
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−15%
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Rules of War resolution 5
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−20%
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Crisis level 2
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−75%
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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 either side as soon as 24 months have 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.
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
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War
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Any
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Offensive war against a Fallen Empire
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- Federation War
- Galactic War
- Great War
- War of the Alliances
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Any
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War between two Federations
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- Annexation Attempt
- Territorial Invasion
- War of Aggression
- War of Conquest
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Conquer
|
|
- War of Beliefs
- War of Ideologies
- War of Philosophies
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Impose Ideology
|
|
- Border War
- Confrontation
- War of Humiliation
- War of Rivalry
|
Humiliate
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Regular empire
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Punitive Expedition
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Humiliate
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Fallen Empire
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Anti AI Police Action
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Outlaw AI
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Buffer Zone Creation
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Decontaminate Border Territories
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Holy Purge
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Cleanse Holy Worlds
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Moral Intervention
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Stop Atrocities
|
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- Freedom Struggle
- Independence War
- Secessionist War
- War of Independence
- War of Liberation
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Independence
|
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- Servitude Campaign
- War of Obedience
- War of Overlordship
- War of Subjugation
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Vassalize
|
|
Tributary War
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Make Tributary
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Not Corporate authority
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Enforced Sponsorship
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Make Tributary
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Corporate authority
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The War In Heaven
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War in Heaven
|
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- Intervention War
- Preemptive Action
- Preventative War
- Self Protection War
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End Threat
|
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- War of Cleansing
- Xeno Filth Removal
- Xeno Purification
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Cleansing
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Fanatic Purifiers civic
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- Extermination Campaign
- Organic Disinfection Program
- Organic Euthanization War
|
Cleansing
|
Determined Exterminator civic
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- Absorption War
- Biomass Accumulation
- Great Gorging
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Absorption
|
|
Machine Uprising
|
Machine Uprising
|
|
Subsidiary Acquisition
|
Make Subsidiary
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Hostile Takeover
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Hostile Takeover
|
|
- Embargo War
- Expulsion War
- War of Expropriation
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Expel Corporation
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War for the Galatron
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Take Galatron
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