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This article has been verified for the current PC version (3.6) of the game.

Wars are not decided only in space. In order to capture enemy planets, entire armies are needed, along with the preparation and battlefield awareness to properly use them. However, planets may only be invaded if the system's starbase has been occupied.

CombatEdit

 
Although secondary to space battles, ground warfare is a vital aspect of many wars.

Ground combat takes place between the planet owner's armies and the invader's armies. The number of armies that can be engaged in combat on either side is five plus one-fifth of the   planet size. Excess armies are initially placed in a reserve area behind the frontline and replace any disengaged or destroyed armies as combat progresses.

Each day, each army engaged in combat deals its health and morale damage to a randomly selected enemy army; armies with less than 50% health are twice as likely to be selected. Armies below 50% health may also disengage from battle; this moves them from the frontline area to the reserve area. Disengaged armies cannot return to the frontline but can still be attacked by enemy armies and destroyed. Disengaged armies are half as likely to be selected as the target of an enemy army. Whenever an army is destroyed, there is a 5% chance for the general leading that army to be killed as well.

Unless an army is immune to morale damage, when its morale drops below certain thresholds, the army will be negatively affected with the following modifiers:

Morale Perc. Penalty
50% <   −25% Army damage
0%   −75% Army damage

After 30 days, the attacker can choose to retreat at any time. However, there is a chance that each retreating army is destroyed while attempting to return to space, with the chance increasing as the army is more damaged. This makes retreating a risky endeavor and something to do only in very poorly chosen engagements.

As long as the ground combat is ongoing, it is possible for either side to land reinforcements, though typically this will only be feasible for the attacker. The ground combat ends when the attacker retreats or all armies of either side are destroyed.

Army rankEdit

Rank Exp Points Effects
Regular 0 - 100 None
Experienced 100 - 1000   +10% Damage
  +10% Morale
Veteran 1000 - 10000   +20% Damage
  +20% Morale
  +10% Health
Elite ≥ 10000   +40% Damage
  +40% Morale
  +20% Health

As armies fight battles, they will increase in rank, improving their stats based on their experience points. Armies get +2 experience points each time they deal damage and +1 when they take damage. Army starting experience can be increased by +100 by each of the following:

  •   Strength of Legions civic
  •   Private Military Companies civic
  •   Military Academy building
  •   Dread Encampment building
  •   Mercenary Liaison Office Corporate holding
  •   Pirate Free Haven Corporate holding

Army stat modifiersEdit

In addition to army rank, several technologies, civics, species and leader traits, and other sources affect army damage, health, and other stats. Additionally,   generals provide   +5% army damage per level and plus other bonuses from traits. Modifiers from species traits affect armies recruited from that species, while   general and   governor traits affect armies led by that general or on planets in that governor's sector. The following is a partial list of army stat modifiers.

Army Health
Source  
  Lithoid species trait +50%
  Clone Soldier Ascendant species trait +25%
  Global Defense Grid technology
(Defense armies only)
+25%
  Resistance is Frugal tradition
(Defense armies only)
+25%
  Nerve Dampeners technology +10%
Army Upkeep
Source  
  Private Military Companies civic −20%
  Strength of Legions civic −20%
  Warbots civic −20%
  Army Logistician/  Parts Cannibalizer general trait −20%
  Master's Teaching: Warring States edict −15%
  Brain Slug Host general trait −15%
  Logistic Understanding ruler trait −10%
  Rules of War resolution 1 or 2 +5%
  Rules of War resolution 3, 4, or 5 +15%

Defense armiesEdit

Defense armies are automatically recruited by certain jobs, based on the species working that job, and can be organic or robotic. Defense armies cannot be moved from the colony they are recruited on and are used only to defend against enemy armies. While they are stronger one-for-one than assault armies and their loss does not cause   war exhaustion, their limited recruitment means that significant investment is necessary to fend off a concentrated attack.

The type of army recruited depends on the pop working the building that spawns them. Defense armies do not incur any upkeep beyond that of the building and pop which creates the army. Defense armies do not cause collateral damage.

Type   Base Damage Morale Damage   Health   Morale Source
  Defense Army 2.25 - 4.50 2.25 - 4.50 250 250 Organic  +1  +2  +2  +3
  Robotic Defense Army 1.50 - 3.00 1.50 - 3.00 250 Immune   Robot  +1  +2  +2  +3
  Undead Defense Army 2.25 - 4.50 3.93 - 7.87 350 Immune Organic  +1  +2  +2  +3  +3
Replaces normal organic defense armies if at least one   necromancer is present
  Offspring-Led Army 2.62 - 5.25 3.41 - 6.82 400 Immune   Progenitor Hive  +2  +3
Replaces normal organic defense armies if at least one   Offspring Drone is present
  Drone Grid 1.65 - 3.30 1.65 - 3.30 220 Immune   Machine Unit  +2  +3
Event spawned defense armies
  Sentinels 6.00 - 12.00 30.00 - 60.00 1400 Immune   Archaeology site event outcome
  Crystalline Bane 52.50 - 105.00 2625.00 - 5250.00 11000 Immune Unexpected Mineral Seams

Assault armiesEdit

An empire can recruit assault armies from a colony based on the species living there. The species must not have   Exempt Military Service rights in order to recruit an army from that species. An empire cannot recruit more assault armies from a species than the total number of pops of that species living in the empire, with the exception of   Clone Armies. Armies not tied to a species, such as the   Xenomorph Army, are unlimited unless otherwise specified.

Unlike defense armies, assault armies are based primarily in space and each recruited army boards a transport ship. Transport ships are unarmed but automatically upgraded with the latest defense and utility components. Assault armies can also be ordered to land on any controlled planet to provide additional defense against invasion.

Type Cost   Time   Upkeep   Base Damage Morale Damage   Collateral Damage   Health   Morale   War exhaustion Requirements Species
  Assault Army   100 90 1 1.50 - 3.00 1.50 - 3.00 100% 200 200 100% Biological
  Slave Army   50 60 0.5 1.50 - 3.00 1.12 - 2.25 150% 200 150 50%   Slave Processing Facility Biological (enslaved)
  Clone Army   75 30 0.75 1.50 - 3.00 1.50 - 3.00 125% 200 200 50%   Gene Banks Biological
  Robotic Assault Army   150 90 1.5 1.50 - 3.00 1.50 - 3.00 150% 400 Immune 50%   Droids
  Robotic Workers Allowed
Robot
  Psionic Army   250 120 2.5 3.00 - 6.00 4.50 - 9.00 50% 350 500 300%   Telepathy Biological (psionic with Utopia)
  Xenomorph Army   200 100 2 3.00 - 6.00 6.00 - 12.00 500% 400 Immune 25%   Morphogenetic Field Mastery None
  Gene Warrior Army   300 150 3 3.00 - 6.00 3.00 - 6.00 75% 500 500 300%   Gene Seed Purification Biological
  Undead Army   100 60 0.75 1.50 - 3.00 2.40 - 4.80 125% 200 Immune 50%   Necromancer jobs Biological
  Hunter-Killer Army   100 90 1 1.50 - 3.00 1.50 - 3.00 200% 200 Immune 50%   Machine Intelligence Robot
  Battle Frame Army   200 120 2 2.25 - 4.50 3.00 - 6.00 200% 500 Immune 100%   Machine Intelligence
  Adaptive Combat Algorithms
Robot
  Mega-Warform   800 500 8 6.00 - 12.00 9.00 - 18.00 400% 1200 Immune 400%   Machine Intelligence
  Biomechanics
None
  Cybrex Warform   250 500 8 7.50 - 15.00 15.00 - 30.00 500% 1400 Immune 400%   Cybrex War Forge relic
Can only be recruited on the capital
None
  Titanic Beast   300 90 1 4.50 - 9.00 9.00 - 18.00 300% 1000 600 200% Titanic Lifeforms event chain
Only 3 can be recruited
None
  Azizian Army   250
  50
90 1 4.50 - 9.00 9.00 - 18.00 100% 1000 400 100% Ice Alien event chain
Only 3 can be recruited
None
  Imperial Legion   300 150 3 3.75 - 7.50 3.75 - 7.50 75% 600 600 300%   Galactic Emperor
  Imperial Legions resolution
Only 12 can be recruited
None
  Mercenary Army   120 0 2 1.65 - 3.30 1.65 - 3.30 250% 200 100 50%   Mercenary enclave deal Biological
  Mechanized Mercenary Army   240 0 5 3.3 - 6.6 3.3 - 6.6 300% 360 200 50%   Mercenary enclave deal Biological
  Psionic Avatar Event 0 0 7.50 - 15.00 15.00 - 30.00 100% 1400 Immune 500%   Shroud event None
  Nanite Warform Event 0 0 15.00 - 30.00 90.00 - 180.00 500% 3600 Immune 400%   A Quiet Stroll event None
  Skeletal Giant Event 0 1.5 4.50 - 9.00 13.50 - 18.00 350% 1400 Immune 50%   Reanimators
Strange Mountain Formation anomaly
None

Orbital bombardmentEdit

Orbital bombardment occurs when a fleet is in orbit around a hostile colony and is generally a precursor to invasion. Genocidal empires can even opt to skip the invasion entirely and simply exterminate all life on the colony. Orbital bombardment causes damage to any armies as well as   devastation. Effectiveness is based on the Fleet Size of the fleet in orbit, where maximum effectiveness is reached at 200 or larger Fleet Size. Assault armies take 5 times more damage from orbital bombardment than defense armies.

Stance Planet damage Army damage Pop kill chance Other effects Requirements
  Selective 50% 100% 25%
  • Does not kill the last 21 Pops
  • Does not bomb planets with no armies on it
None
  Indiscriminate 100% 150% 50%
  • Does not kill the last 11 Pops
    Not Pacifist
  Armageddon 150% 200% 100%
  • If the last pop is killed, the planet becomes a   Tomb World
Any of:
  •   Fanatic Purifiers
  •   Determined Exterminator
  •   Become the Crisis
  Javorian Pox 20% 150% 150%
  • Does not kill   Mechanical Pops
  • If the last pop is killed, the planet becomes a   Tomb World
  •   Javorian Pox Sample relic activation
  •     Not Pacifist
  Raiding 100% 50% 100%
  • Abducts pops instead of killing them
  • Species with Displacement, Neutering or Extermination species rights will still be killed
  • Does not cause Terror Bombing opinion if successfully abducted
  • Does not kill or abduct the last Pop
Either:
  •   Barbaric Despoilers
  •   Nihilistic Acquisition

Orbital Bombardment Damage dealt to enemy planets can be increased by the following:

Source   Damage
  Overwhelming Force tradition +20%
  Orbital Trash Disperser component +25%
  Munitions Plant juggernaut aura +30%
  Crisis level 3 +20%

Orbital Bombardment Damage taken from enemy fleets can be reduced by the following:

Source   Damage
  Subterranean origin −75%
  Planetary Shield Generator building −50%
  Survival of the Fittest tradition −25%
  Never Surrender tradition −25%
  Fortress World designation −10%
  Fortress Station designation −10%

DevastationEdit

  Devastation Orbital Bombardment   FTL inhibitors   Tree of Life Time To

Recover

  Damage to armies   Kills pops
0%-24.9% 50%   Functional Alive 498
25%-49.9% 100%   Functional Alive 998
50%-74.9% 100%   Disabled Destroyed 1498
75%-100% 200%   Disabled Destroyed 2000

Devastation is a measure of how much damage has been caused to the colony's infrastructure. It goes from 0 to 100%, and every 1% devastation causes a 1% decrease in   housing,   amenities,   trade value,   resources from jobs,   upkeep from Jobs,   growth speed and   immigration pull.

Devastation is primarily caused by orbital bombardment, and to a lesser degree assault armies. Assault armies have a Collateral Damage modifier that determines how fast they cause devastation. Defense armies do not cause any devastation.

Devastation decreases by 0.05% daily if the colony is not being invaded or bombarded.

ReferencesEdit

Game concepts
Exploration ExplorationFTLAnomalyArchaeological siteRelicsPre-FTL speciesFallen empireEventsSpaceborne aliensGuardiansMaraudersCaravaneers
Celestial bodies Celestial bodyColonizationTerraformingPlanetary featuresPlanet modifiers
Species SpeciesTraitsPopulationPop modificationSpecies rightsEthics
Governance EmpireGovernmentCivicsPoliciesEdictsLeaderFactionsTechnologyTraditionsSituations
Economy EconomyPlanetary managementDistrictsBuildingsHoldingsJobsDesignationTradeMegastructures
Diplomacy DiplomacyRelationsGalactic communityFederationsSubject empiresIntelligenceAI personalities
Warfare WarfareSpace warfareLand warfareStarbaseShipShip designerCrisis
Others The ShroudL-ClusterUnique systemsPreset empiresAI playersEaster eggs