Ground Combat

Base Ground Combat Rules

Ground combat is conducted after the naval combat phase of each increment. One combat round will be performed for every eight hours that passed in the increment. Combat potentially takes place on any system body where populations exist from two or more hostile powers. If only one side has ground forces present, there may be a conquest (rules and code TBD). If ground forces are present from two or more hostile powers, ground combat will take place.

Ground forces can be assigned one of four field positions: Front Line Attack, Front Line Defence, Support, and Rear Echelon. Units in Support and Rear Echelon positions cannot directly attack hostile forces, but if they possess elements with bombardment weapons they may be assigned to support a front line formation. Support and Rear Echelon formations can also potentially provide anti-air cover and supply to front line units. Only formations with all elements supplied can be placed in Front Line Attack mode. Formations placed in Front Line Attack mode lose any fortification bonus.

Each race involved in a combat on a system body creates a list of its own formations on that system body (even if in multiple populations), plus a list of hostile alien formations, even if they are from multiple alien races in multiple populations. Hostile formations are checked for their weighted size. This is based on actual size for front line, 25% for support, and 5% for rear echelon. Each hostile formation is given a range for potential selection based on its weighted size.

Each front line friendly formation randomly targets a hostile formation. Friendly units with Front Line Defence can target hostile front line formations. Friendly units with Front Line Attack can target any hostile formation, although Support and Rear Echelon are less likely given their smaller weighted size. The more formations that are pushed into front line positions, the less likely it is that rear areas will be attacked.

Support and Rear Echelon formations that contain formation elements with bombardment weapons can be assigned to support front line formations that are part of the same organisation. Formations in a Support position with light bombardment weapons will fire with the front line formations. Formations in a Support position with medium/heavy bombardment weapons, or formations in a Rear Echelon position with heavy bombardment weapons, will fire in a subsequent phase.

Once a front line formation (or a light bombardment element in Support) has been matched against a hostile formation, each friendly individual unit (a soldier or vehicle) in that formation engages a random element in the hostile formation, with randomisation based on the relative size of the hostile formation elements. This represents combined-arms cooperation (infantry supporting tanks, etc.).

Once all front line attacks have been concluded, each unit in each element providing supporting bombardment will engage either:

the hostile formation being targeted by the friendly formation they are supporting, or
one of the hostile formation’s own supporting elements (counter-battery fire).

If the hostile formation is targeted, each unit in the supporting artillery element engages a random element in the hostile formation. If a hostile supporting element is targeted, all fire is directed against that element.

Supporting medium artillery will choose between hostile forces in Front Line or Support positions (ignoring Rear Echelon). Heavy artillery can select targets in any field position.

Once all initial combat is complete, there is a chance for a breakthrough. Each defending formation is checked:

Breakthrough Procedure

Cohesion Damage: For each formation element:; Cohesion Damage = (Element Class Size) × (Units Destroyed in Combat Phase) × (100 / Element Morale)

The total Cohesion Damage is summed for all elements and compared to the formation size. This value (0–100%) is the Formation Cohesion Rating.

Breakthrough Value

For each front line formation that attacked the defender:

Static elements have zero Breakthrough Value.
Vehicle elements:

(Element Class Size) × (Element Units) × (Element Morale / 100)

Infantry elements:

Same formula × 0.5

The total Breakthrough Value is summed and compared to formation size. If the formation is in Front Line Attack, multiply by 2. This value (0–200%) is the Formation Breakthrough Rating.

Breakthrough Potential

Breakthrough Potential = (Defending Cohesion Rating) × (Attacking Breakthrough Rating)

If ≥ 30%, a breakthrough occurs.

Each formation that creates a breakthrough mounts a second attack. This attack:

does not benefit from supporting artillery or fighter support
functions as if the formation is in Front Line Attack
may target any hostile formation

Breakthroughs are more likely when:

multiple attackers strike one defender
the defender suffers high casualties
casualties fall on large-class elements
defender morale is low
attacker is vehicle-heavy
attacker is in Front Line Attack
attacker morale is high

Combat Resolution

When a formation element engages a hostile element, supply is checked. If supply is unavailable, only 25% of units fire.

For each attacking unit:

To Hit Chance: Base chance = 20% × (Dominant Terrain To Hit Modifier) × (Element Morale / 100) × (Base To Hit for target unit class if target is not fortified)

Fortification Modifier: Target Fortification Level × (Dominant Terrain Fortification Modifier).; If target is not fortified, this modifier = 1.

Environment Modifier: Based on gravity, pressure, temperature, and element capabilities.; Each untrained environment doubles the modifier.

Terrain Capability Modifier: If trained for dominant terrain, modifier = 0.5.

Final Chance to Hit: Final Chance to Hit = To Hit Chance / (Fortification Modifier × Environment Modifier × Terrain Capability Modifier)

The unit fires each weapon it has (except non-bombardment weapons for units bombarding from Support or Rear Echelon). If the to-hit roll ≤ Final Chance to Hit, the weapon hits.

Armour Penetration: If AP ≥ Armour → penetration; If AP < Armour → chance to penetrate = (AP / Armour)^2

Damage: If penetration occurs → chance to destroy target = (Weapon Damage / Target Hit Points)^2

If a target is destroyed:

the firing element gains morale
the target element loses morale
morale gain/loss is doubled in Front Line Attack mode

All combat is simultaneous and losses are applied after all firing is complete. Multi-way conflicts with multiple races on each side are possible.