13.3 Ground Combat

Updated: v2026.01.30

Ground combat in Aurora C# resolves battles between opposing formations on the same planetary body. Combat occurs after each naval phase, with one ground combat round per eight hours of game time. \hyperlink{ref-13.3-11}{[11]} Ground combat activates automatically whenever hostile forces from two or more powers occupy the same system body with populations.

Important: Ground forces will not engage enemy forces unless the owning race is set as hostile in the diplomacy settings. Without this setting, forces from different powers can coexist on the same body without fighting. Before landing troops on an enemy colony, verify the target race is marked hostile in the Diplomacy window (see Section 15.4 Diplomacy), or your forces will simply sit alongside the enemy without combat.

13.3.1 Planetary Terrain

Updated: v2026.01.30

Each planet receives a dominant terrain type determined by environmental conditions. Terrain significantly affects combat through fortification modifiers, to-hit penalties, and interactions with unit combat capabilities.

13.3.1.1 Terrain Type Determination

Barren/Mountain Default Rules: Worlds meeting any of these conditions default to “Barren” terrain:

Temperature below -100C or above 200C
No atmosphere
Atmospheric pressure exceeding 10 atm

Exception: Worlds with platelet or extreme tectonics receive “Mountain” terrain instead of Barren.

Other Worlds: Check environmental compatibility tables to determine eligible terrain types, randomly selected from the available terrain pool.

13.3.1.2 Available Terrain Types (v2.0.0+)

As of v2.7.1, there are 41 distinct terrain types. \hyperlink{ref-13.3-1}{[1]} The original set was expanded with additional types to better represent planets with significant orbital temperature variation:

High-Variation Terrains (require minimum 30-degree orbital temperature swing):

Terrain	Temperature Range	Notes
Arid	-50C to 200C	Max 30% hydrosphere; broader than standard desert
Arid Mountain	-50C to 200C	Mountain variant of arid
Arid Rift Valley	-50C to 200C	Rift variant of arid
Grassland	-40C to 80C	Covers steppe, prairie, savanna equivalents
Alpine Grassland	-40C to 80C	Mountain variant of grassland
Boreal Forest	-50C to 40C	Cold-climate forest
Boreal Mountain Forest	-50C to 40C	Mountain variant of boreal forest

\hyperlink{ref-13.3-3}{[3]}

Standard Additional Terrains:

Cold Steppe, Coniferous Forest, Rainforest, Mountain Rainforest, Subarctic, Subarctic Mountain, Alpine Forest

These additions enable planets with significant orbital eccentricity to maintain realistic biomes rather than defaulting to extreme terrain classifications.

13.3.1.3 Terrain Effects on Combat

Terrain Type	Fortification Modifier	To-Hit Modifier	Notes
Steppe	1.0	1.0 (no penalty)	Open terrain; no penalty to orbital fire
Desert	0.75	1.0	Arid environments; minimal concealment
Swamp	0.5	1.0	Wet terrain; poor for fortification
Temperate Forest	1.25	0.5	Moderate concealment
Mountain	2.0	0.5	Elevation advantage
Jungle	1.5	0.25	Dense vegetation favors defense
Jungle Mountain	3.0	0.125	Combined terrain; extreme defense
Rift Valley	1.5	0.75	Broken terrain
Barren	1.0	1.0	No concealment advantage

\hyperlink{ref-13.3-2}{[2]}

The fortification modifier from terrain multiplies the element’s fortification level. If a formation element’s fortification level is greater than 1, it is multiplied by the fortification bonus of the dominant terrain.

13.3.1.4 Dominant Terrain Change (v2.0.0+)

Terrain assignment and change is governed by orbital mechanics:

Fast-Orbiting Bodies (orbital period < 6 months):

Bodies with orbits shorter than six months (and their moons) can only be assigned dominant terrains that fall within the minimum and maximum temperatures of their orbit
This prevents unrealistic constant terrain shifts during brief orbital periods

Slower-Orbiting Bodies:

Terrain changes based on current temperature, which may shift as the body moves around its orbit
Eccentric orbits can produce terrain variation as temperature fluctuates with orbital position

13.3.1.5 Terraforming Effects on Terrain (see Section 5.5 Terraforming)

Terrain can shift through three mechanisms:

Type Progression: Worlds with base types (Barren, Mountain, Rift Valley) transition between similar terrain categories as environmental conditions improve through terraforming
Environmental Incompatibility: Unsuitable terrain regenerates when conditions no longer support current type
Orbital Temperature Variation: Bodies with eccentric orbits may experience terrain shifts as their temperature changes with orbital position (v2.0.0+)

13.3.1.6 Combat Capabilities vs. Terrain

The game consolidates terrain into three primary combat specialization categories:

Mountain Warfare: Applies to any mountain or rift valley terrain type, including combined terrain (e.g., Jungle Mountain)
Desert Warfare: Covers desert, cold desert, and arid classifications, including combined variants (e.g., Arid Mountain)
Jungle Warfare: Applies to jungle and rainforest terrain, plus combined forms

Modifier Application:

Single Specialization: Divides the environmental penalty by 2 (50% reduction)
Dual Specialization: Stacks multiplicatively. A unit with both Jungle and Mountain Warfare divides the environment modifier by 4 (75% reduction) in combined terrain like Jungle Mountain

13.3.2 Field Positions

Updated: v2026.01.30

Forces in ground combat can occupy one of four field positions, each with distinct tactical roles:

13.3.2.1 Front Line Attack

Can target any enemy position (front line, support, rear echelon)
Rear areas are less likely targets due to weighted-size calculations
Forfeits all fortification bonuses while in attack mode (requires live testing — #747)
Generates doubled morale gains from kills (requires live testing — #747)
Only fully-supplied formations may assume this position (requires live testing — #747)

Tactical Note: When forces first land on a hostile planet, set them to front-line attack immediately. Newly-landed forces have no fortification, so the defensive bonus of front-line defence is wasted. Front-line attack lets your troops engage the enemy right away rather than sitting in reserve while the enemy fires on them. Once the initial engagement stabilizes, you can transition select formations to defence to begin fortifying.

13.3.2.2 Front Line Defence

Can only engage other front-line hostile formations
Retains fortification bonuses
Standard morale gains from kills

13.3.2.3 Support

Indirect fire only; cannot directly attack
Provides bombardment support
Fires simultaneously with ground support fighters and orbital bombardment
Same target selection options as heavy bombardment

Artillery Targeting by Weight Class:

Medium Artillery: Targets individual elements within a formation. Damage is applied to specific units, making it effective for attrition of exposed elements.
Heavy Artillery: Targets entire formations. Damage is distributed across the formation, making it effective for suppressing large concentrations rather than destroying individual units.

This distinction affects damage distribution: medium artillery concentrates fire for focused kills, while heavy artillery spreads damage across the formation, degrading overall combat power rather than eliminating specific elements.

13.3.2.4 Rear Echelon

Limited fire capability
Primarily logistical support role
Less likely to be targeted by enemy front-line attack formations

13.3.3 Combat Resolution

Updated: v2026.01.30

13.3.3.1 Target Selection

Each front-line formation randomly targets a hostile formation based on weighted formation sizes. Larger formations are more likely to be targeted. Front-line defence can only engage front-line hostiles, while attack formations can target any position.

No Targeting Priority Control: (unverified — #866)

Ground unit weapons cannot be directed at specific enemy types. Targeting is random – weapons fire independently and players cannot specify that anti-vehicle weapons should prioritize enemy armor over infantry or vice versa.

Workarounds for targeting control:

Multi-wave deployment: Deploy infantry-killer units first, then armor units after enemy infantry is eliminated
Weapon load diversification: Equip heavy vehicles with mixed weapon types (HCAP, CAP) rather than all SHAV, since most enemies are infantry/light armor
Formation mixing: Create separate unit models with different weapons and combine them in formations

Targeting Range Modifiers by Position:

The effective size of a formation for targeting purposes is modified by its field position:

Field Position	Size Modifier for Targeting
Front Line (Attack or Defence)	100% of formation size (no modification)
Support	25% of formation size
Rear Echelon	5% of formation size

(requires live testing — #747)

This means support and rear echelon formations are significantly less likely to be targeted by front-line attack formations. Rear echelon units in particular are nearly invisible to targeting selection, making them safe positions for headquarters and logistics elements.

13.3.3.2 To-Hit Calculation

The fundamental accuracy formula:

Final To-Hit = (Base 20%) x (Terrain Modifier) x (Morale Ratio) / (Fortification x Environment x Unit Defensive Value)

(requires live testing — #747) \hyperlink{ref-13.3-10}{[10]}

Modifiers:

Fortification Level: Divides incoming accuracy (higher = harder to hit)
Environmental Penalties: x2 multiplier per unsuitable condition (gravity, pressure, temperature)
Terrain-Trained Units: 0.5x modifier per matching capability (stacks multiplicatively)
Morale: Ratio between attacker and defender morale affects accuracy
Commander GCO Bonus: Improves accuracy of direct-fire weapons \hyperlink{ref-13.3-9}{[9]}
Commander GCA Bonus: Improves accuracy of indirect-fire weapons \hyperlink{ref-13.3-9}{[9]}

Ground Commander Skill Distinctions: (unverified — #866)

Skill	Affects	Combat Type
Ground Command Offense (GCO)	Hit chance for direct fire weapons	Ground Combat only
Tactical (on ground commanders)	Hit chance of STO weapons under command	Space-to-Ground Ordnance only

Important: Tactical skill on ground commanders has no effect on ground combat – it only affects Space-to-Ground Ordnance (STO) weapons. This is a common source of confusion because Tactical skill is typically associated with naval commanders.

Commander Hierarchy Bonus Stacking:

Ground combat bonuses apply through the command hierarchy with diminishing returns by echelon:

Direct Commander: Provides 100% of their ground combat bonus (GCO, GCD, GCA, etc.) to the formation they directly command (requires live testing — #747)
Superior Commander (one level up): Provides 25% of their bonus to formations commanded by their subordinate commanders (requires live testing — #747)

These bonuses stack additively. For example, a battalion with a commander providing 10% GCO, subordinate to a brigade commander providing 20% GCO, receives: 10% (direct, 100%) + 5% (superior, 25% of 20%) = 15% total GCO bonus. This rewards proper hierarchical organization with competent senior officers.

13.3.3.3 Damage Resolution

Upon a successful hit, damage is resolved in two stages:

1. Armor Penetration:

Penetration chance = (Weapon AP / Target Armor)^2 \hyperlink{ref-13.3-5}{[5]}
If AP >= Armor, penetration is automatic \hyperlink{ref-13.3-5}{[5]}
If AP < Armor, penetration becomes increasingly unlikely

2. Destruction:

Destruction probability = (Weapon Damage / Target Hit Points)^2 \hyperlink{ref-13.3-5}{[5]}
If Damage >= HP, destruction is automatic \hyperlink{ref-13.3-5}{[5]}
If Damage < HP, destruction becomes increasingly unlikely

13.3.3.4 Morale Effects

Successful kills generate morale gains for the attacker (doubled in attack mode)
Targets suffering kills receive morale losses
Morale affects to-hit calculations and breakthrough potential
Maximum morale = 100 + (5 x commander training bonus percentage)
Morale recovers between combat rounds based on commander training bonus

13.3.3.5 Breakthrough Mechanics

When a defending formation takes sufficient damage, breakthrough may occur:

Breakthrough potential = Formation Cohesion Rating x Formation Breakthrough Rating
Commander GCM bonus increases breakthrough probability \hyperlink{ref-13.3-9}{[9]}
When breakthrough potential >= 30%, attacking formations gain additional attacks (requires live testing — #747)
Breakthrough attacks do NOT include support capabilities (no artillery, no air support)
Breakthrough attacks can target all hostile formations regardless of field position
Represents exploitation of a gap in enemy lines

Breakthrough Value Calculation:

The breakthrough value for individual elements is calculated as:

Vehicles: Element Class Size x Number of Units x (Morale / 100)
Infantry: Element Class Size x Number of Units x (Morale / 100) x 0.5

(requires live testing — #747)

Infantry elements contribute half the breakthrough value of equivalently-sized vehicle elements, reflecting the role of armored forces in exploitation operations.

13.3.3.6 Counter-Battery Fire

Artillery units in the Support field position can engage enemy artillery that has fired during the current combat round. This counter-battery fire mechanic enables suppression of enemy fire support:

Trigger: When enemy artillery fires from the Support position, its location becomes known to opposing forces for counter-battery targeting
Eligible Units: Any friendly artillery in the Support position can direct counter-battery fire against identified enemy artillery
Effect: Counter-battery fire allows suppression or destruction of enemy indirect fire assets, reducing their bombardment effectiveness over time
Tactical Implication: Players should consider rotating artillery units or distributing them across multiple formations to reduce vulnerability to counter-battery fire. Concentrating all artillery in a single formation makes it an attractive counter-battery target.

Tip: Counter-battery fire is one of the few ways to directly engage enemy support-position units. If enemy artillery is inflicting heavy casualties, assigning your own artillery to counter-battery duty can neutralize the threat, though at the cost of losing your own bombardment against front-line targets.

13.3.4 Fortification

Updated: v2026.01.30

Fortification represents ground forces digging in and constructing defensive positions. Fortified formations are dramatically harder to dislodge.

13.3.4.1 Fortification Levels by Unit Type

Unit Type	Self-Fortification	Max Fortification	Time to Self-Fortify
Infantry	3	6	30 days
Static Weapons	3	6	30 days
Light/Medium/Heavy Vehicles	2	3	30 days
Super-Heavy Vehicles	1.5	2	30 days
Ultra-Heavy Vehicles	1.25	1.5	30 days

\hyperlink{ref-13.3-4}{[4]}

13.3.4.2 Automatic Self-Fortification

All elements move from non-fortified to their maximum self-fortification level in 30 days without outside assistance: (requires live testing — #747)

Progression occurs automatically and linearly
Only occurs when formations are NOT set to front-line attack mode
Commander GCD bonus increases effective fortification level when fortified

13.3.4.3 Construction-Assisted Fortification

Construction elements can fortify other units beyond their self-fortification maximums:

Only works on elements already at their self-fortification maximum
Given sufficient capacity, a construction element can fortify any other element from its self-fortification level to maximum fortification in 90 days (requires live testing — #747)
Construction capacity = construction rating x unit count x racial construction rating x commander bonus x 100 tons (requires live testing — #747)
Multiple construction elements work in parallel

13.3.4.4 Fortification in Combat

Fortification level divides incoming to-hit probability
Fortification level is further multiplied by the dominant terrain’s fortification bonus
Front-line attack formations forfeit all fortification bonuses
Moving/loading a formation resets fortification to 0 (requires live testing — #747)
Taking casualties does NOT reduce fortification level (requires live testing — #747)

13.3.4.5 Breaking Fortifications

Approaches to overcoming fortified positions:

Overwhelming Force: Raw combat power to overcome the defensive multiplier
Orbital Bombardment: Reduce fortification levels from orbit before landing
Ground Support Fighters: Aerial bombardment bypasses some fortification benefits
Siege: Sustained combat attrits defenders even through fortifications (costly)
Combined Arms: Heavy armor + artillery most effective against fortified positions

13.3.5 Ground Forces Detection

Updated: v2026.01.30

Ground forces use a specialized detection system that rewards defensive positioning.

13.3.5.1 Detection Mechanics

Ground forces are treated as size-1 for detection purposes (requires live testing — #747)
Resolution-1 sensors are best for detecting them
Makes ground forces inherently harder to spot than larger space targets

13.3.5.2 Signature Calculation

Formation Signature = (Total Formation Signature) / 100

Element Signature = (Unit Size x Unit Number) / (Fortification Level x Dominant Terrain Fortification Modifier)

(requires live testing — #747)

13.3.5.3 Practical Signature Interpretation

When viewing ground force sensor returns, the thermal and EM signatures provide a rough guide to enemy strength. As a rule of thumb, a signature reading gives you the product of unit size and unit count divided by fortification and terrain modifiers. A large signature could mean many unfortified troops in open terrain, while a small signature could mean either a small force or a large force that is heavily fortified in defensive terrain. If you detect a moderate signature on a jungle-mountain world, assume the actual force is significantly larger than the raw number suggests, since the terrain fortification modifier (up to 3.0) dramatically suppresses signatures.

13.3.5.4 Strategic Implications

Well-fortified units have smaller signatures than unfortified ones of equivalent strength
Observers cannot distinguish between “a small force, or a well-fortified larger force” without additional intelligence
Defensive positioning and fortification reduce detectability
Reconnaissance is more difficult against prepared positions

13.3.5.5 Hostile Force Intelligence During Combat

Intelligence about enemy ground unit composition becomes progressively more accurate as combat continues. The system uses a formula based on the number of combat rounds:

Intel Error Range = 200 / Number of Combat Rounds
Intel Error = 1 + (Random(Intel Error Range) / 100)

(requires live testing — #747)

After each combat round, estimates are recalculated. The actual number of hostile units is either multiplied or divided by the Intel Error value (50/50 chance).

Practical Examples:

Combat Rounds	Possible Estimate Range (for 1,000 actual units)
2 rounds	500 - 2,000 units
10 rounds	833 - 1,200 units
20 rounds	909 - 1,100 units

Early estimates are highly unreliable, but extended combat provides increasingly accurate force composition data. Players gradually learn the true strength of enemy forces through sustained engagement.

13.3.5.6 Alien Ground Unit Intelligence

Players accumulate knowledge about alien ground unit classes through combat engagement. Intelligence is tracked in the Diplomacy and Intelligence window alongside ship and sensor data.

Identification Thresholds (combat milestones):

Milestone	Requirement	Information Revealed
Weapon Detection	Alien unit fires on friendly forces	Weapons systems
Unit Type ID	20 hits scored against the unit class	Base type (infantry, vehicle, etc.)
Armor Discovery	20 armor penetrations against the class	Armor value
Hit Point Learning	20 units of the class destroyed	Total hit points

(requires live testing — #747)

Requirements:

Players must have their own ground forces present on the same body where alien units operate
Intelligence thresholds are per-class (each alien unit class must be independently identified)

Renaming Alien Units (v2.0.0+):

The Intelligence window allows players to rename each alien ground unit class (same interface as renaming alien ship classes)
Custom designations are used in all ground combat reports throughout the interface
Enables clearer battlefield communication based on tactical experience with the enemy

13.3.6 Ground Support Fighters (Removed in v2.8.0)

Updated: v2026.01.30

Warning: Ground support fighters were removed from Aurora C# in v2.8.0. Fighter-based ground support orders, fighter pods, and all related mechanics are no longer available in current versions. Orbital bombardment by ships remains the primary method for providing fire support to ground forces (see Section 13.3.8 Orbital Bombardment Support and Section 13.3.10 Naval Bombardment of Ground Forces).

This section is retained as a historical reference for players using versions prior to v2.8.0. All mechanics described below are non-functional in v2.8.0 and later.

Historical content (pre-v2.8.0 only)

Ground support fighters provided aerial assistance during ground combat, using fighter pods rather than standard missiles. **Deployment Requirements:** - Fighters required a "Provide Ground Support" order targeting a friendly population - Order persisted until manually removed - Only fleets carrying appropriate fighter pods qualified - Eligible fleets appeared in a dedicated section on the Ground Combat Window - Fleets on ground support duty at their designated population could not be engaged in standard naval combat **Combat Integration:** - Attacked simultaneously with bombardment elements - Same target selection options as heavy bombardment - Accuracy influenced by crew quality and unit morale - Aircraft avoided environmental penalties affecting ground-based units **Fire Direction Limits:** - Each Forward Fire Direction component permitted support from up to 6 fighters - Excess fighters beyond FFD capacity fired with reduced accuracy: `Accuracy Modifier = (Number of FFD x 6) / Number of Fighters` **Fighter Pod Systems:** - Specialized fighter pods (bombardment, autocannon, or air-to-air configurations) - Configuration changes occurred while stationed in hangars

13.3.7 Ground-Based Anti-Aircraft Fire

Updated: v2026.01.30

AA units defend against ground support fighters using specialized targeting mechanics.

13.3.7.1 Engagement Rules

AA units participate in normal ground combat using standard combat values
Can draw supply twice if engaged in both ground-to-ground AND ground-to-air combat simultaneously
All AA damage applies after all attacks resolve in the combat sequence

13.3.7.2 AA Targeting Priority

All AA units in a formation directly attacked by aircraft select a random aircraft from those attacking that formation
Medium/Heavy AA in parent formations of attacked units target aircraft engaging subordinates
Heavy AA units engage random hostile aircraft, including those on combat air patrol

13.3.7.3 Accuracy Formula

AA To-Hit = (10% x (Tracking Speed / Aircraft Speed) x (Morale / 100)) / Environment Modifier

(requires live testing — #747)

Units untrained in specific environments face a 2x penalty per environmental condition
Higher tracking speed relative to aircraft speed improves hit chance
Commander GCAA bonus improves AA accuracy \hyperlink{ref-13.3-9}{[9]}

13.3.7.4 Damage Against Aircraft

Aircraft Damage = ((Ground Damage Value / 20)^2) rounded down

(requires live testing — #747)

Example: An AA unit with 40 ground damage inflicts 4 points of damage to fighters (40/20 = 2, 2^2 = 4).

13.3.8 Orbital Bombardment Support

Updated: v2026.01.30

Ships equipped with energy weapons can provide precision ground combat assistance when assigned to support friendly formations. This is distinct from general orbital bombardment.

13.3.8.1 Deployment

Ships must receive a “Provide Orbital Bombardment Support” order targeting a friendly population
Ships in orbit appear in the “Orbital Bombardment Support” section of the Ground Combat Window
Players drag and drop vessels onto ground formations for assignment
Unlike ground support fighters, these ships remain vulnerable to naval combat and surface-to-orbit weapons

13.3.8.2 Combat Mechanics

Ships attack simultaneously with bombardment elements
Each vessel fires once per ground combat phase (requires live testing — #747)
Cannot fire if the ship fired during the preceding naval combat phase in the same increment (requires live testing — #747)
Uses same accuracy system as ground unit bombardment

13.3.8.3 Accuracy Modifiers

Modified by crew grade and morale
Tactical officer contributes 100% of their ground support bonus (requires live testing — #747)
Ship commander provides 50% of their bonus (requires live testing — #747)
Standard ground support accuracy calculations apply

13.3.8.4 Damage Conversion (Ship-to-Ground)

Energy weapon damage converts to ground combat values using:

Ground Damage = 20 x sqrt(Point Blank Ship-to-Ship Damage)
Armor Penetration = Ground Damage / 2

(requires live testing — #747)

Examples:

Weapon	Ship PB Damage	Ground AP	Ground Damage
10cm Railgun	~0.25	5	10
10cm Laser	~3	17.3	34.6
Heavy Laser	Higher	Higher	Higher

(requires live testing — #747)

13.3.8.5 Fire Direction Requirements

Each formation FFD component enables 1 orbital bombardment ship or 6 ground support fighters \hyperlink{ref-13.3-6}{[6]}
If a formation loses FFD capability, ships automatically seek alternative formations at the same location
Formations without FFD cannot receive orbital bombardment support

13.3.8.6 Strategic Considerations

More accurate than general bombardment (precision directed by ground controllers)
Ships fire far less frequently than in general bombardment role
Ships are vulnerable to STO weapons while in support orbit
Powerful but costly advantage requiring dedicated warships

13.3.9 Ground Combat Events

Updated: v2026.01.30

C# Aurora generates granular combat reports with multiple detail levels, allowing players to filter information according to preference.

13.3.9.1 Combat Summary Organization (v2.6.0)

Added: v2.6.0

Ground combat summaries are organized by planet or ship rather than empire-wide. This location-based grouping makes it significantly easier to track combat progress and conduct after-action analysis for specific engagements:

Planetary Combat: Summaries are grouped by the planet where combat is occurring
Boarding Combat: Summaries are grouped by the ship being boarded
Improved Tracking: Players can quickly assess the status of individual engagements without sifting through combined empire-wide reports

13.3.9.2 Tactical-Level Reports

Event Type	Description
Element vs GUC	One element vs one GUC (shots, hits, penetrations, kills)
Ship vs GUC	One ship vs one hostile ground unit class

13.3.9.3 Aggregate Reports

Event Type	Description
GUC vs GUC Summary	Friendly vs hostile ground unit class performance comparison
Attack vs GUC Summary	All friendly ground force attacks against specific hostile types
Orbital vs GUC Summary	All ship attacks against particular hostile ground unit classes

13.3.9.4 Formation-Level Reports

Event Type	Description
Formation Attack Summary	Hostile unit types and quantities destroyed by a specific friendly formation
Ground Attack Summary	Comprehensive list of hostile units destroyed by all surface and orbital forces
Element Loss Summary	Enemy attack results against friendly formation elements
Formation Loss Summary	Types and quantities of friendly units lost per formation
Ground Defence Summary	Total friendly unit casualties across all formations
Breakthrough Achieved	Notification when a formation achieves a breakthrough

Players can filter events to avoid excessive detail or enable granular information for role-playing and after-action reports.

13.3.10 Naval Bombardment of Ground Forces

Updated: v2026.01.30

Naval Bombardment of Ground Forces (NBG) allows ships to mass-bombard ground-based sensor contacts using missiles or energy weapons. This operates as part of normal naval combat without requiring friendly ground forces or fire direction support, distinct from the precision Orbital Bombardment Support in Section 13.3.8 Orbital Bombardment Support.

13.3.10.1 Targeting Mechanics

Each weapon type on each ship targets separately. A ship with 10cm and 15cm railguns makes two independent targeting rolls. Target formations are selected based on a weighted random roll, with the weighting based on formation size. Within selected formations, shots target random elements using additional weighted rolls.

13.3.10.2 Energy Weapon NBG

Ships using energy weapons for NBG have one-third of the chance to hit compared to using Orbital Bombardment Support (Section 13.3.8 Orbital Bombardment Support) and cannot benefit from ground support bonuses.

To-Hit Formula:

NBG Energy To-Hit = (Base 20% / 3) x (Terrain To-Hit Modifier) / (Target Fortification x Terrain Fortification Modifier)

(requires live testing — #747)

This means blind-firing energy weapons at enemy concentrations is not very effective, especially in difficult terrain.

13.3.10.3 Missile NBG

Missiles for NBG have a 100% base chance to strike their targets due to nuclear warheads requiring less precision than energy weapons.

Damage Distribution:

Missile warhead damage is distributed across multiple attacks to simulate blast effects:

1 attack at full warhead damage
2 attacks at half damage
4 attacks at quarter damage
Continues doubling attacks at half damage until damage per attack drops below 1

Each attack can hit multiple targets within a formation. The number of sub-attacks per attack equals 50 / target size. (requires live testing — #747)

Example: An 8-point missile warhead against infantry (size 5):

1 attack at 8 damage, hitting 10 targets (50/5)
2 attacks at 4 damage, hitting 10 targets each
4 attacks at 2 damage, hitting 10 targets each
8 attacks at 1 damage, hitting 10 targets each
Total: 15 attacks hitting 10 targets each = 150 infantry elements attacked

13.3.10.4 Damage Conversion

Ground combat damage for orbital weapons:

Ground Damage = 20 x sqrt(Point Blank Ship-to-Ship Damage)
Armor Penetration = Ground Damage / 2

Examples:

Weapon	Ship PB Damage	Ground AP	Ground Damage
10cm Railgun	0.25	5	10
10cm Laser	3	17.3	34.6
25cm Laser	16	40	80
9-point Warhead	9	30	60

(requires live testing — #747)

13.3.10.5 Environmental Impact

Effect	Missile Warheads	Energy Weapons
Radiation increase	Equal to warhead size	None
Dust level increase	Equal to warhead size	5% of damage amount

13.3.10.6 Collateral Damage

Each NBG shot has a one-third chance to also strike the population itself, inflicting installation damage and population losses (requires live testing — #747)
Conversely, planetary bombardment attacks (targeting population/installations) have a one-third chance to hit any ground forces present, regardless of detection status (requires live testing — #747)
All ground combat to-hit modifiers apply to these collateral hits

13.3.10.7 Constraint

Ships cannot perform orbital bombardment in the ground combat phase if they fired in the preceding naval combat phase of the same increment.

13.3.11 Surface-to-Orbit Weapons

Updated: v2026.01.30

Surface-to-Orbit (STO) weapons are ground unit class-mounted beam weapon systems that can engage ships in orbit. They represent a significant ground-based anti-ship capability.

13.3.11.1 Component Generation

STO weapons automatically generate integrated components when designed as a ground unit class:

Beam Fire Control: Created with either:

4x Racial Fire Control Range + 1x Tracking Speed (for normal anti-ship weapons), or
1x Range + 4x Tracking Speed (for point defense variants)

The fire control features a 25% range bonus versus ship-mounted equivalents. Cost and size are 50% of the ship version due to dedication to a single weapon (uses the single weapon fire control system). (requires live testing — #747)

Active Sensor: Resolution-1 with minimum 5-ton size, range matching the weapon’s maximum range. (requires live testing — #747)

Reactor: Generates sufficient power for the weapon capacitor at normal cost/size. (requires live testing — #747)

ECCM: Optional 50-ton component at half normal cost. (requires live testing — #747)

13.3.11.2 STO Targeting Options

Ground elements with STO capability can select from these targeting modes:

Target random/largest/smallest/fastest/slowest/easiest ship
Target shipyards or populations (same body restriction applies)
Target ground forces or STO ground forces
Final Defensive Fire (full or surface-only)
Area Point Defence against missiles

13.3.11.3 STO AI Targeting (v2.0.0+)

The AI uses a custom priority list based on distance, size, and known capabilities rather than simple player-selectable options. This ensures the AI prioritizes high-value or vulnerable targets rather than taking low-chance shots against warships while ignoring closer commercial or unarmed targets.

13.3.11.4 Detection and Contact Classification

Before Firing: STO elements that have not fired are detected with other ground forces as a standard ground forces contact. Their active sensors are detectable through EM sensors like any other active sensor, but EM detection alone does not flag the element as an STO weapon.

After Firing: Once an STO element fires, detecting races flag it as a separate “STO Ground Forces” contact distinct from standard ground forces. All known STO elements on a planet are grouped as a single STO Ground Forces contact.

Multiple Knowledge States: An STO element may be known to some races (flagged as STO) while still being part of the normal ground forces contact for other races that have not witnessed it fire.

Targeting Implications: Players can choose to engage either the identified STO elements specifically or target the general ground forces, which might contain undetected STO units.

13.3.11.5 Strategic Considerations

STO weapons make sustained orbital bombardment costly for the attacker
Ships in bombardment support orbits are vulnerable to STO fire
Suppressing STO assets before committing to prolonged bombardment is advisable
Multiple formations with STO weapons stack their defensive contribution
STO point defense variants can engage incoming missiles, providing ground-based anti-missile capability

13.3.12 General Orbital Bombardment

Updated: v2026.01.30

General orbital bombardment allows ships in orbit to fire on enemy surface positions to soften defenses, reduce fortification levels, or support friendly forces. This differs from the precision support in Section 13.3.8 Orbital Bombardment Support and the mass NBG bombardment in Section 13.3.10 Naval Bombardment of Ground Forces.

13.3.12.1 Bombardment Mechanics

Eligible Weapons: Energy weapons (lasers, particle beams, railguns, etc.) and missiles
Targeting: Ships in orbit of a body with enemy ground forces bombard surface formations
Damage: Applied to enemy ground formations, destroying elements and reducing fortification
Terrain Modifier: Terrain to-hit modifier applies to bombardment accuracy (e.g., Jungle Mountain’s 0.125 modifier makes bombardment far less effective)

13.3.12.2 Bombardment Types

Targeted Bombardment: Focuses fire on military formations, minimizing collateral damage. Less total damage but more precise
General Bombardment: Fires indiscriminately at the surface. Maximum military damage but significant collateral damage to colony infrastructure and population

13.3.12.3 Collateral Damage

Population Casualties: General bombardment kills civilians at approximately 100,000 civilians per point of warhead strength. (requires live testing — #747) Even a modest missile salvo can devastate a colony’s population, making orbital bombardment an extremely blunt instrument against inhabited worlds.
Infrastructure Destruction: Installations (factories, mines, labs) can be destroyed
Political Impact: Excessive civilian casualties may have diplomatic consequences
Capture vs. Destroy: Excessive bombardment defeats the purpose of capturing a colony

13.3.12.4 NPR Bombardment Behavior (v2.0.0+)

As of v2.0.0, some Spoiler and NPR factions will avoid bombing populations except when specifically targeting Surface-To-Orbit (STO) weapons. This behavior is influenced by the race’s xenophobia setting. Low-xenophobia races are more likely to restrict their bombardment to military targets only, while highly xenophobic races may still employ indiscriminate bombardment.

13.3.12.5 Reducing Fortification

Sustained bombardment gradually reduces defending formation fortification levels
High-damage weapons (particle beams, heavy lasers) are most effective
Terrain modifier significantly affects bombardment effectiveness against fortified positions
Monitor progress through the ground forces display

13.3.12.6 Anti-Aircraft and STO Defense

AA elements reduce bombardment effectiveness
STO weapons can engage bombarding ships, making sustained bombardment costly (see STO AI Targeting above)
Multiple formations with AA/STO stack their defensive contribution
Consider suppressing AA/STO assets before committing to prolonged bombardment

13.3.13 PDC Ground Assault Mechanics

Updated: v2026.01.30

Planetary Defence Centres (PDCs) interact with ground combat in specific ways that differ from open-field engagements. Understanding these mechanics is essential when planning assaults on fortified worlds.

13.3.13.1 PDC Defense Rules

Isolated Defense: Only the defending troops garrisoned within the specific PDC under attack participate in its defense. Troops in other PDCs or in open-field positions do not reinforce the defenders of a PDC being assaulted.
No Reinforcement: Defenders cannot reinforce a PDC that is already under ground attack. Once an assault begins, the garrison fights with whatever forces were present when the attack started.
No Magazine Reload: A PDC under ground attack cannot reload its weapon magazines from the planetary stockpile. The PDC fights with whatever ammunition it had loaded when the assault commenced.
Offensive Sorties: Troops garrisoned in OTHER PDCs (those not currently under attack) can emerge to fight offensively against attacking ground forces in the open. They are not trapped inside their PDC.

13.3.13.2 Why Ground Forces Are Needed

PDC weapons systems (missiles, energy weapons, point defense) are designed to engage spacecraft in orbit, not ground troops on the surface. A PDC’s formidable anti-ship armament cannot be turned against infantry or vehicles assaulting its perimeter. This is why ground forces are required to neutralize PDCs – orbital bombardment may suppress them, but only ground assault can capture or destroy them from the surface.

13.3.13.3 Tactical Implications

Divide and Conquer: Since PDC garrisons fight in isolation, an attacker can concentrate overwhelming force against one PDC at a time while the others cannot intervene
Starve Ammunition: Sustained ground assault prevents magazine reloads, eventually silencing the PDC’s anti-ship weapons even if the garrison holds
Exploit Sorties: When defenders emerge from other PDCs to fight offensively, they lose their PDC’s protective fortification, making them vulnerable to destruction in the open

13.3.14 Boarding Combat

Updated: v2026.01.30

Boarding combat allows ships to attempt capture of enemy vessels through marine assault. This is a specialized form of ground combat that occurs in the confined spaces of a starship.

Diplomatic Consequence (v1.13.0+): As of v1.13.0, boarding an alien ship is classified as a hostile act. This triggers the same diplomatic penalties as an unprovoked attack, immediately dropping relations to hostile (-100) if not already hostile. Plan boarding operations with full awareness of their diplomatic ramifications.

13.3.14.1 Requirements

Attacking ship must have a boarding-equipped troop transport bay \hyperlink{ref-13.3-7}{[7]}
Only all-infantry formations can participate in boarding
Target ship must not be faster than attacking ship
Fleet must end movement in target’s location to trigger the attempt
Infantry with “Boarding Combat” capability are far more effective \hyperlink{ref-13.3-8}{[8]}
Boarding Combat specialization requires Powered Armour technology as a prerequisite – the option will not appear in the unit designer until this tech is researched \hyperlink{ref-13.3-12}{[12]}

13.3.14.2 Boarding Attempt (Transfer Phase)

Individual soldier success chance for reaching the target:

Transfer Success = 10% x (Boarding Ship Speed / Target Ship Speed)

(requires live testing — #747)

Ships 10x faster achieve automatic success (100%)
Units with “Boarding Combat” capability receive double the normal hit chance during boarding operations (only need 5x speed differential for certainty) \hyperlink{ref-13.3-12}{[12]}
Failed boarders are killed – they represent soldiers lost in the transfer attempt
If an HQ unit dies and only one exists, the formation commander automatically perishes

13.3.14.3 Breaching Phase

After successful transfer, boarders must breach the hull:

If armor is already breached (from prior combat damage), survivors enter immediately
Otherwise, boarders apply a “breaching charge to destroy one armour at the weakest point every thirty seconds” until access is gained
Thicker armor means longer breaching time and more vulnerability

13.3.14.4 Internal Combat

Once inside the target vessel:

Combat rounds occur every 300 seconds (5 minutes) (requires live testing — #747)
Defender fortification bonus: Defenders receive a fortification value of level 2, representing dug-in positions in corridors, choke points, and makeshift barricades. Attackers have a base fortification of level 1 (before any commander GCD bonuses). (requires live testing — #747) This gives defenders a significant accuracy reduction against incoming fire without needing time to fortify.
No retreat: Boarding is a one-way commitment. Once marines have transferred to the target vessel, they cannot withdraw or return to their ship. Combat continues until one side is completely eliminated.
Each unit randomly selects opposing targets
Standard to-hit, armor penetration, and damage calculations apply

13.3.14.5 Marine Detachments

Ships can carry marine detachments – ground force formations assigned directly to the ship – that serve as dedicated defenders against boarding actions. Marines are significantly more effective than regular crew at repelling boarders, as they use their full combat statistics (weapons, armor, hit points) rather than the crew’s improvised defense values. Assigning a marine detachment to high-value ships (carriers, flagships, transports) provides a substantial defensive upgrade against boarding attempts.

13.3.14.6 Crew Defense

The target ship’s crew forms a temporary defensive formation:

Crew defense has armor equal to half the lowest racial armor for infantry (requires live testing — #747)
Represents improvised defense by non-combat personnel
Smaller crews are overwhelmed more quickly
Larger crews provide more targets but also more defenders

13.3.14.7 Deployment Window

If a boarding shuttle can reach the target ship within 5 seconds of deployment, the troops will deploy before the shuttle can be intercepted and destroyed. (requires live testing — #747) This makes boarding viable even against ships with point defense, provided the boarding vessel is close enough at the moment of launch. Plan your approach to close within this 5-second transfer window before committing marines.

13.3.14.8 Capture Consequences

Upon defeating all defenders:

Ship transfers ownership to the boarding faction
Captured ship receives a “01 status” – an overhaul factor of 0.01 (essentially requires complete overhaul) (requires live testing — #747), indicating the ship needs full crew replacement and extensive repair (see Section 14.2 Maintenance)
Simulates sabotage, locked controls, and unfamiliar systems
Ship must be returned to a shipyard for overhaul before being fully operational
Reverse Engineering: Captured ships can be reverse-engineered at a research facility to unlock alien technology components, or scrapped at a shipyard to recover materials. Even a heavily damaged capture may yield valuable technological insights that justify the boarding casualties.

13.3.14.9 Collateral Damage

Internal combat causes ship damage:

Fractional damage results apply as percentage chances of full-point damage conversion
Critical systems may be damaged during the fighting
The captured ship may require significant repairs beyond the overhaul

13.3.14.10 Boarding Infantry Design

Boarding combat is extremely brief – resolved in 300-second (5-minute) increments – which makes logistics capacity completely irrelevant for boarding teams. Marines will never consume supplies during the engagement. Instead, invest in maximum survivability and lethality: heavy powered infantry armor for the best protection, genetic enhancements for increased hit points, and crew-anti-personnel weapons optimized for close-quarters shipboard fighting. A boarding team designed this way will vastly outperform general-purpose infantry in the confined, short-duration engagements of shipboard combat.

13.3.14.11 Practical Tips

Boarding is most effective against slower or disabled ships
Fast boarding ships with large infantry capacity maximize transfer success
The “Boarding Combat” capability is essential for infantry intended for boarding operations
Consider the cost-benefit: a heavily damaged captured ship may not be worth the marine casualties
Elite boarding infantry with genetic enhancements make the best marines due to their increased hit points

13.3.15 Surrender

Updated: v2026.01.30

Ground forces can be compelled to surrender when overwhelmed by superior opposing forces on the same body.

13.3.15.1 Population Surrender Mechanics

Populations (colonies) surrender when the occupying ground force strength exceeds the defender’s remaining capability:

The ground forces strength required to force a population to surrender is based on the population’s remaining military power
Surrender evaluates the total combat power of attacking forces versus defending forces
Populations without adequate military defense may surrender to invading ground forces
As of v1.13.0, the surrender threshold for populations with STO (Surface-To-Orbit) weapons is correctly calculated – prior versions required 100x the intended ground force strength to compel surrender when STOs were present

13.3.15.2 Conquest Rewards

When you successfully conquer a colony through ground combat or forced surrender, you gain several benefits:

Reparations: The conquered colony yields wealth and mineral resources as spoils of war. The reparation amount is determined by the colony’s existing wealth stockpile, mineral reserves, and the economic output of its installations. Larger, more developed colonies yield proportionally greater reparations. This provides an immediate economic benefit to the conquering empire.
Captured Technology: Research facilities and installations on the conquered world may yield alien technology components that can be reverse-engineered, potentially unlocking tech advances your empire has not yet discovered. The probability of recovering usable technology increases with the number of intact research facilities captured. Prioritize minimizing orbital bombardment damage to research infrastructure if technology capture is a goal.
Intact Installations: Colony installations (factories, mines, research labs, shipyards, etc.) may survive the conquest intact, particularly if the attacker relied on ground assault rather than heavy orbital bombardment. Surviving installations immediately begin producing for the conquering empire once the colony stabilizes. This makes ground-only conquest significantly more valuable than bombardment-followed-by-occupation.
Population Absorption: The conquered population becomes part of your empire as a subject people. They contribute to your labor force and economy, but suffer from elevated unrest due to the conquest (modified by the Political Status Modifier for conquered peoples). Managing conquered populations requires attention to stability and garrison forces sufficient to meet the Required Garrison Strength formula (see Section 13.1.8 Colony Garrison and Security).

13.3.15.3 Naval Surrender (for reference)

AI naval fleets may also surrender under specific conditions:

Conditions: Fleet must be unarmed, badly damaged, or incapable of completing its mission while under attack from energy weapons
Decision Factors: Fleets may attempt evasion, surrender, or ramming based on crew attributes
Crew Traits: Determination and Xenophobia ratings influence which action occurs
Exception: Certain spoiler races will never surrender under any circumstances
Consequence: Surrendered ships receive an overhaul factor of 0.01 (matching ships captured through boarding)

13.3.16 AI Ground Offensives (v2.0.0+)

Updated: v2026.01.30

The AI uses improved decision-making for ground combat operations, particularly regarding when to transition from defensive to offensive postures.

13.3.16.1 AI Offensive Decision Process

Previous Behavior: The AI would only launch ground offensives with specific formation types (such as armor units), creating exploitable situations
Current Behavior (v2.0+): The AI assesses whether to mount offensive operations using formations that would normally remain in defensive positions

13.3.16.2 AI Intelligence Assessment

The AI evaluates available intelligence before deciding on offensive action:

Known Information: Assesses player armor, hit points, and offensive capabilities based on the Alien Ground Unit Class intelligence system
Default Assumptions: When lacking information, the AI assumes basic infantry until discovering otherwise
Adaptive Behavior: The AI may launch aggressive offensives against unknown forces, then revert to defensive postures once it gains better intelligence about enemy composition

13.3.16.3 AI Tactical Considerations

Fortification Trade-offs: The AI accounts for the benefits of maintaining fortification bonuses versus initiating offensive operations
Exploitation: The AI will now attack reluctant landing forces rather than allowing indefinite defensive standoffs
Strategic Flexibility: AI decisions create more dynamic ground combat scenarios where players cannot exploit purely passive AI behavior

13.3.17 Combat Summary

Updated: v2026.01.30

13.3.17.1 Ground Combat Flow (per 8-hour phase)

Supply Check: Verify formation supply status; unsupplied units restricted to 25% fire rate
Target Selection: Front-line formations randomly select targets weighted by formation size
Bombardment Phase: Support elements, ground support fighters, and orbital bombardment ships fire
Direct Combat Phase: Front-line elements engage selected targets
AA Phase: Anti-aircraft elements engage attacking aircraft (damage applied after all attacks)
Casualty Assessment: Hits resolved through AP check then damage check; destroyed elements removed
Morale Update: Kills generate morale gains/losses; morale recovery calculated
Breakthrough Check: If breakthrough potential >= 30%, additional attacks without support
Fortification Update: Self-fortification progresses (if not in attack mode); construction elements work

13.3.17.2 Key Formulas Reference

Calculation	Formula
Armor Penetration	(AP / Armor)^2
Destruction	(Damage / HP)^2
Base To-Hit	20% x terrain / (fortification x environment)
AA To-Hit	10% x (tracking/speed) x (morale/100) / environment
AA Damage vs Aircraft	((Ground Damage / 20)^2)
Ground Damage (Orbital)	20 x sqrt(ship PB damage)
Orbital Bombardment Accuracy	Modified by Tactical Officer (100%) + Ship Commander (50%)
Boarding Transfer	10% x (boarding speed / target speed)
GSP per 10 rounds	penetration x damage x shots
Formation Signature	(size x count) / (fortification x terrain modifier) / 100
Intel Error Range	200 / Number of Combat Rounds
Intel Error	1 + (Random(Intel Error Range) / 100)

UI References and Screenshots

Updated: v2026.01.29

Ground Forces Window Layout — combat status and unit deployment
Forum screenshots (archived – pentarch.org URLs no longer accessible as of 2026-01):
- Ground Rules (was: pentarch.org/steve/Screenshots/GroundRules005.PNG) – combat resolution
- Ground Support (was: pentarch.org/steve/Screenshots/GroundSupport002.PNG) – orbital bombardment support

Section 5.5 Terraforming – Terrain changes from terraforming
Section 12.6 Damage and Armor – Orbital bombardment and radiation effects
Section 12.7 Planetary Defence Centres – Orbital bombardment defense and fortification interactions with PDCs
Section 13.1 Unit Types – Ground unit class design and capabilities
Section 13.2 Training and Transport – Deploying forces to combat zones
Section 14.2 Maintenance – Overhaul requirements for captured ships
Section 16.2 Skills and Bonuses – Ground combat commander bonuses
Worked Example: Ground Invasion – Planetary assault planning and execution walkthrough

References

\hypertarget{ref-13.3-1}{[1]}. Aurora C# game database (AuroraDB.db v2.7.1) – DIM_PlanetaryTerrain. Contains 41 distinct terrain types (TerrainID 1-41). Previously stated as 38; corrected to 41. Additional terrains added since v2.0.0 include Hot Desert (39), Cold Desert Mountain (40), and Hot Desert Mountain (41).

\hypertarget{ref-13.3-2}{[2]}. Aurora C# game database (AuroraDB.db v2.7.1) – DIM_PlanetaryTerrain. Fortification/To-Hit modifiers confirmed from database: Steppe (1.0/1.0), Desert (0.75/1.0), Swamp (0.5/1.0), Temperate Forest (1.25/0.5), Mountain (2.0/0.5), Jungle (1.5/0.25), Jungle Mountain (3.0/0.125). Corrections: “Forest” renamed to “Temperate Forest” with fortification corrected from 1.0 to 1.25; “Rift Valley” corrected from 2.0/0.5 to 1.5/0.75; “Barren” corrected from 0.5/1.0 to 1.0/1.0.

\hypertarget{ref-13.3-3}{[3]}. Aurora C# game database (AuroraDB.db v2.7.1) – DIM_PlanetaryTerrain. High-variation terrain types confirmed with MinTempRange=30: Arid (ID 31), Arid Mountain (32), Arid Rift Valleys (33), Grassland (34), Alpine Grasslands (25), Boreal Forest (35), Boreal Mountain Forest (36). Temperature ranges verified from MinimumTemperature/MaximumTemperature columns.

\hypertarget{ref-13.3-4}{[4]}. Aurora C# game database (AuroraDB.db v2.7.1) – DIM_GroundUnitBaseType. Fortification values confirmed: Infantry (3/6), Static (3/6), Light Vehicle (2/3), Medium Vehicle (2/3), Heavy Vehicle (2/3), Super-Heavy Vehicle (1.5/2), Ultra-Heavy Vehicle (1.25/1.5). Note: “Standard Vehicle” corrected to “Medium Vehicle” per database naming.

\hypertarget{ref-13.3-5}{[5]}. Aurora C# game database (AuroraDB.db v2.7.1) – DIM_GroundComponentType. Weapon penetration and damage values confirmed for all component types. The (AP/Armor)^2 penetration formula and (Damage/HP)^2 destruction formula are from Steve Walmsley’s ground combat mechanics documentation on the Aurora Forums.

\hypertarget{ref-13.3-6}{[6]}. Aurora C# game database (AuroraDB.db v2.7.1) – DIM_GroundComponentType. Forward Fire Direction (ID 20): FireDirection=1. The “6 fighters per FFD” and “1 orbital bombardment ship per FFD” values from Steve Walmsley’s ground combat rules.

\hypertarget{ref-13.3-7}{[7]}. Aurora C# game database (AuroraDB.db v2.7.1) – FCT_TechSystem. Troop Transport Boarding Bay techs confirmed: Standard (ID 65454, 2,500 RP), Small (ID 65848, 100 RP), Very Small (ID 67060, 100 RP). All are CategoryID=32 (Planetary Combat).

\hypertarget{ref-13.3-8}{[8]}. Aurora C# game database (AuroraDB.db v2.7.1) – DIM_GroundUnitCapability. Boarding Combat (ID 1): InfantryOnly=1, CostMultiplier=2.5. FCT_TechSystem: Boarding Combat Capability (ID 65822) = 2,500 RP.

\hypertarget{ref-13.3-9}{[9]}. Aurora C# game database (AuroraDB.db v2.7.1) – DIM_CommanderBonusType. Ground combat bonus types confirmed: Ground Combat Offence (BonusID 30, GCO), Ground Combat Defence (BonusID 10, GCD), Ground Combat Artillery (BonusID 31, GCA), Ground Combat Manoeuvre (BonusID 32, GCM), Ground Combat Logistics (BonusID 33, GCL), Ground Combat Anti-Aircraft (BonusID 35, GCAA), Ground Combat Occupation (BonusID 29, OCC), Ground Combat Training (BonusID 12, GCT). All have Ground=1, confirming ground-force-only restriction.

\hypertarget{ref-13.3-10}{[10]}. Aurora Forums – Steve Walmsley’s ground combat mechanics posts. Combat resolution formulas (base 20% to-hit, armor penetration, destruction probabilities), field position mechanics, fortification timing, breakthrough mechanics, boarding combat details, and orbital bombardment conversion formulas. (forum-sourced; specific post URLs unavailable)

\hypertarget{ref-13.3-11}{[11]}. Aurora C# game database (AuroraDB.db v2.7.1) – FCT_Game.MinGroundCombatPeriod = 28800 seconds (8 hours). This defines the interval between ground combat rounds.

\hypertarget{ref-13.3-12}{[12]}. Aurora Forums – Steve Walmsley response in “Is boarding specialization still a thing?” (https://aurora2.pentarch.org/index.php?topic=13828.0). Confirmed: Boarding Combat specialization requires Powered Armour technology as a prerequisite and provides double (2x) hit chance during boarding operations.