Jump to Combat Strength Modifications


A unit can't enter a tile occupied by an enemy unit. Instead, it will ask if you want to attack. Combat usually locks units in battle until one is destroyed. An attack costs the aggressor one move-point. It will also lose moves proportional to damage it suffers. Attacking a tile does not move there — the surviving unit remains where it was.

Some combat rules are obvious—units must have non-zero attack strength to attack. Defenders with zero defense lose immediately. There are limits on which units can attack which others. Most Land units can only attack other Land units. Most ships can attack other ships and also Land units. Helicopters and Marines can attack Land and Sea units and can be attacked by most units. Bombers and Missiles can attack any Land or Sea unit. Fighters and Anti-Aircraft Artillery can attack almost all units.

Fighters in a city or a Base can be attacked by land. Ships in port cities suffer defense penalties. Marines and Anti-Aircraft Artillery can attack targets from aboard ship or Helicopter; other Land units must disembark and wait one turn before engaging enemy units (unless the ship first docks on a tile where Unloading and Deboarding with no move penalty is legal.

A unit ordered to Sentry remains in place indefinitely and no longer asks for orders each turn. Sentried units can be reactivated manually by selecting them, or activate automatically if an enemy unit comes into view (or if they have finished healing.) Sentried units will report on the first non-allied unit they see moving within their vision or 3 tiles of their location (whichever is less.) Sentried units get no defense bonus.

Land units can be ordered to Fortify, which gives an extra defense bonus for the unit if it is attacked next turn and has at least ⅑ remaining move point left to fortify. Once fortified, units enjoy the same +50% advantage as land units in a city. A unit with no remaining moves can't fortify—it needs remaining move-points to begin the next turn fortified. Unless specified otherwise, a unit who moves, attacks, or does a Special Unit Attack will lose its fortified status and have to re-fortify over turn-change to gain it back. The exceptions are a few units whose special tactics allow them to preserve their fortified state. The Phalanx and Marines can do Special Unit Attacks and Standard Attacks without losing fortified status. Archers are able to do Volley Attacks without losing fortified status, but not Standard Attacks.

Spies in combat. Spies can harm enemy units by doing sabotage.

Combat Mechanics[]

There are two types of combat: Standard Attacks, which are the majority of all combat; and Special Attacks, which are special tactical engagements.

Standard Attacks[]

Each unit begins combat with one or more hitpoints—the amount of damage it can sustain. (See Units for stats on each unit type.) Combat consists of successive rounds of violence between the units, which cannot be interrupted and ceases only when a unit dies by reaching zero hitpoints. (An exception is most ancient sea units—they can attack for a maximum of 15 combat rounds.) In each combat round, only one unit succeeds in wounding the other. The damage a unit inflicts with each blow is called its firepower.

In each combat round, which unit inflicts damage is based on probability. The attacker's chance is relative to its attack strength, while the defender's chance is relative to its defense strength. For example, on an open field with no other bonuses: Archers have attack strength 3 and attack a Phalanx with defense strength 2. For each round, the Archers will have odds of inflicting damage, while the Phalanx has odds.

Special Unit Attacks[]

These are unique tactical engagements different from the standard "to-the-death" fatal combat. SUA are typically—but not always—ranged attacks which gain the advantage of not incurring retaliation, but (usually) at the cost of not doing fatal damage. In spite of usually not being fatal, such special attacks are quintessential to the science of Tactics. They can affect movement and the ability to gain strategic positioning. SUAs may cause injury or fatigue that may have decisive results when followed up with standard combat. They may degrade or compromise large numbers of enemies at little or no cost. In MP2C, a handful of special units have Special Unit Attacks to replicate the historic tactical abilities that these units famously exploited for advantage. Phalanx, Archers, Legion, Siege Ram, Zealots, Marines, Zeppelins, and Battleships, have different types of SUA that emulate the historic abilities of those units..Note: You can see the statistics for any SUA by hovering the mouse over the menu button for the Special Unit Attack.

Special Unit Defense[]

Just as some units can do Special Unit Attacks, other units' tactical abilities let them retaliate against units that expose their location via ranged attack and other forms of SUA. Special Unit Defense (SUD) is an exception to the rule that Special Unit Attacks have no risk of retaliation. When attacked from range, these units can do a SUD retaliation attack against the location the attacker exposes by making the attack. The following units can retaliate against special unit attacks with SUD: Archers, Catapult, Cannon, Artillery, Howitzer, Battleship, Helicopter. Archers and Battleships are the only units that can do both SUA and SUD.

NOTE: The requirements for Special Unit Defense are the same as for Special Unit Attacks and regular Attack: all three actions require a unit to have moves left in order to do it.

Tired attack[]

When units do standard attacks or special unit attacks with less than one full move-point, they are penalized because of tiredness. Only a fraction of their attack strength is used. If they have move-points, they will attack with strength. If they have move-points, they will attack with strength, and so on.

There are other factors which affect combat strength. These are summarized in the tables below:

Combat Strength Modifications[]

Veteran Bonus
Unit is not veteran ("green") ×1.00
Unit is veteran 1st level ("veteran") ×1.50 V1
Unit is veteran 2nd level ("hardened") ×1.75 V2
Unit is veteran 3rd level ("elite") ×2.00 V3
Unit is veteran 4th level (elite-2, "crack") ×2.10 V4
Unit is veteran 5th level (elite-3, "master") ×2.20 V5
Unit is veteran 6th level (elite-4, "champion") ×2.30 V6

Combat Strength Modifications
Terrain Multiplier defense bonus, TM × TM Lowlands city with Fortifications add to TM +0.17
Terrain includes a River ×1.33
Unit is tired (move points < 1) ×(moves left)
Phalanx or Pikemen attacking and attacker owns the Agōgē of Sparta ×1.5
In city with SAM Battery against Air units (not Stealth or Missile)... ×2
.... In city with SAM Battery against Stealth Air units ×1.25
In city with SDI Defense against Missile ×2
In city with Coastal Defense against Sea units ×2
In city with Fortifications (no Walls) vs. Land unit (see Ballistic units) ×1.5
In city with City Walls against Land unit (but, see Ballistic units) ×3
Land unit/Fighter/Helicopter in Fort against Land or Sea (not Armor) ×1.33
Non-Sea unit in Naval Base -- **same as Fortress (below) **
Fighter in Fortress against Land or Sea units (except Armor) ×1.33
Land unit/Heli in Fortress against Land or Sea units (except below...) ×2
... Land unit in Fortress against Armor I, Helicopter, or Air units ×1.66
... Land unit in Fortress against Armor II ×1
Sea unit in Naval Base. ×2
Land unit fortified or in city ** ×1.5

These factors are combined: Each factor that qualifies as true is multiplied into the final bonus.

** Land units able to fortify get a 1.5x "automatic fortified" bonus in a city, regardless if fortified or not. Those unable to fortify don't get the bonus.

The Base bonus page gives a chart for the bases above. Also see: Terrain bonuses and base bonuses.

There are more circumstances that result in adjustments to combat:

Special Combat Modifications
Pikemen defends vs. Mounted units (except Cavalry) Defense strength ×2
AEGIS Cruiser defends vs. Aircraft, Missile or Helicopter Defense strength ×3
Missile Destroyer defends vs. Aircraft, Missile or Helicopter Defense strength ×2
AAA or Mobile SAM attacks or defends vs Aircraft or Helicopter Strength ×2
Armor II vs. Missile Defense strength ×2
Stealth Aircraft attacks vs. units with Anti-Air bonus Attack strength ×1.25
Ship defends while inside city: "Pearl Harbor Effect" Attacker firepower ×2

Ship firepower reduced to 1

Sea unit attacks Land unit Both have firepower reduced to 1
Sea unit defends vs. Marines Defense strength ×2
Cruiser,Battleship,Missile Destroyer,Aegis Cruiser defend vs Submarine Defense strength ×2
Destroyer defends vs. Submarine Defense strength ×4
Knights defend vs. Mounted units (except Cavalry) Base Defense strength = 3
Knights defend vs. any Foot soldiers Base Defense strength = 2


General Promotions. Most units have a chance to gain a higher veteran level when they survive combat. Higher veteran levels impart three kinds of bonuses to units.

Movement bonuses. Veteran levels may impart a movement bonus. (1) Crack V4 land units gain + move-point over standard. (2) Air and Sea units gain +1 move-point over standard. (3) Marines gain +²⁄₉ moves for every veteran level.

Work-rate bonuses. Veteran military units who are able to work tiles get the same bonus to their work-rate as they do to their combat strength.

Combat bonuses. All veteran military units gain veteran bonuses to their Combat Strength. With two exceptions, all combat units have the following chances of promotion:

Land/Sea Promotion Odds.

Land and Sea Units: Veteran Promotion Chances
V0→V1 (Green to Veteran) 50% V1
V1→V2 (Veteran to Hardened) 33% V2
V2→V3 (Hardened to Elite) 20% V3
V3→V4 (Elite to Crack) 15% V4
V4→V5 (Crack to Master) 15% V5
V5→V6 (Master to Champion) 15% V6

Air Promotion Odds. Offensive Air units' promotions are slightly lower, to balance getting more attacks per turn:

Air Units: Veteran Promotion Chances
V0 (Green to Veteran) 40% V1
V1 (Veteran to Hardened) 25% V2
V2 (Hardened to Elite) 16% V3
V3 (Elite to Crack) 10% V4
V4 (Crack to Ace) 10% V5
V5 (Ace to Top Gun) 10% V6

Marines' Promotion odds represent foot soldiers' upgrades to modern weaponry as the game progresses:

Marines: Veteran Promotion Chances
V0 (Green to Veteran) 60% V1
V1 (Veteran to Hardened) 50% V2
V2 (Hardened to Ranger) 40% V3
V3 (Ranger to Commando) 30% V4
V4 (Commando to Green Beret) 20% V5
V5 (Green Beret to Navy SEAL) 15% V6

Marines' veteran bonuses represent improved strength of weapons and special ops forces in the late game:

Veteran Combat Strength Multiples
V0 (Green) 100%
V1 (Veteran) 150% V1
V2 (Hardened) 175% V2
V3 (Ranger) 250% V3
V4 (Commando) 300% V4
V5 (Green Beret) 350% V5
V6 (Navy SEAL) 400% V6

Note: 1. Marines are the strongest foot unit, yet come in the middle of the tech tree. Rather than upgrade to a newer unit, the game represents the need for experience and training for modern special ops. 2. A veteran Marine usually needs 5 battles to become Ranger, where it can defend slightly better than older cheaper faster Alpine Troops. 3. A veteran Marine requires 20 successful battles on average to become Navy SEAL, a rare unit attacking at 89% the strength of a green Howitzer. 4. Thus, the late bonuses serve to slightly mitigate the rapid uselessness that occurs for late-game foot units; and provide a role for multipurpose special ops in modern warfare.

Injured Movement[]

Damaged Land and Sea units begin each turn with fewer move-points than normal. Their move-points will be proportional to (current_hitpoints / total_hitpoints). However, each unit class is guaranteed a minimum amount of moves: this is referred to as min_speed. Land units have a min_speed of 1. Ships made from wood have a min_speed of 2. Modern metallic ships have a min_speed of 3. Aircraft suffer no min_speed losses and always keep 100% of their move points.


Damaged units enter combat at a disadvantage. To regain hitpoints they must spend turns neither moving nor attacking. They regain health each turn according to the table below:

Healing Factor Modifications
Resting unmoved +10%
Fortified *additional +10%
In a City +33%
Unit is a Ship (see chart below) *additional +8%
Fortress: Land or Helicopter unit. +25%
Fort: Land units only. +10%
Airbase: Aircraft . +15%
Airbase: Helicopters . +25%
Land unit in city with Barracks Completely restored
Sea unit in city with Port Facility Completely restored
Air/Helicopter unit in Airport city. Completely restored
  • A fortified unit gets +10% for resting unmoved and +10% for being fortified, for a total of +20%.
  • If you sentry a damaged unit, it will become active and request new orders after its hit points are fully restored.
  • Except for the Crew Repair bonus (below), all healing factors require a whole turn of resting (not moving) in order to activate.

Crew repairs heal ships 8% every Turn Change regardless of whether the unit has moved.

Crew Repair
Ship type Repair rate
10hp 0hp
20hp 1hp
30hp 2hp
40hp 3hp

You may produce new V1-Veteran units in a city if it has the appropriate building for its type:

B.barracks i Barracks cost:30 upkeep:1

requires:Warrior Code makes vet. Land units

B.barracks ii Barracks II cost:35 upkeep:1

requires:Gunpowder makes vet. Land units

B.barracks iii Barracks III cost:40 upkeep:1

requires:Mobile Warfare makes vet. Land units

B.port facility Port Facility cost:60 upkeep:3 requires:Amphibious Warfare

makes vet. Sea units

B.airport Airport cost:120 upkeep:3

requires:Radio vet. Air & Missile units

*Marines made in a city with Barracks III, Port Facility, AND Airport come out V2. Sun Tzu's War Academy gives an additional +1 veteran level to Land units. Magellan's Expedition gives an additional +1 veteran level to Sea units.

Stack-Kill, Stack-Escape; Cities, Forts, Fortresses[]

One unit defends a stack[]

When several units on the same tile are attacked, the unit most capable of defense protects the entire tile.

  • More precisely, for all defenders on the tile which can defend against the attacker, winning chance is calculated to the precision of 0,001­%, and the best result is chosen to defend the whole stack. If several units have similar results, the cheapest unit defends first.


If defenders are inside a City or Base, a lost battle only kills one defending unit. Otherwise, loss of the defender results in Stack-Kill: the loss of every attackable unit on the tile.

When a unit transporting other units is in combat, only the attacking unit participates in the engagement, and its passengers are lost if it loses.


Air and Sea units (from Galleon onward) can sometimes survive a Stack-Kill event. When they are present in a stack whose defender has died, each has a separate 60% chance to escape to an adjacent tile if and only if it has as at least as many move points as the attacker. For example, if an attacker with 2 remaining move points kills the defender of a stack, each defending unit in that stack needs 2 or more remaining move points to qualify for a chance to escape. Escape Charm is the name given to an additional 1% bonus that is awarded for each surplus move point the defender has over the attacker: for example, if a Submarine with 1 move point kills a stack that has a ship with 5 remaining move points, the ship receives an "Escape Charm" bonus of 5-1 = 4%, which is added to its Stack-Escape odds.

Stack-Escape simulates the ability of Air and Sea units to escape in multiple directions if "faster" than the attacker, and provides superior playability and realism in their ability to escort each other.

Note: Destroyer types and Stealth Aircraft have a higher 67% chance to stack escape. Submarines have a 75% chance. Satellites always stack escape.

City Population Loss[]

When a City loses a defending unit to an attack by a Land unit, there is a 50% chance that a city citizen will be lost if the city has no Fortifications or City Walls1, 2. Once the last defender is gone, you may conquer the city with a Land unit or Helicopter. Ships and aircraft can attack cities but not capture them. A captured City loses 1 population, which destroys the City if it is size 1. Upon capture of a City, each building has a 20% chance of being destroyed. The victor may steal technology blueprints from the former owner.

1Knights cause population loss only during city capture, not when killing units inside the city.

2The server setting killcitizen_pct regulates the chance of one citizen being lost, and defaults to 50% in MP2-Caravel



Forts, Fortresses, Castles, and Bunkers[]

Building a Fort requires Masonry. A Fortress requires an existing Fort and Construction tech. To build one of these, move Settlers, Workers, Legions, Engineers, or Proletarians to a tile and give the order. A Fort or Fortress can go anywhere except on a city-center or in water. More information is available by clicking the link for each base type. Castles and Bunkers are types of modified Fortresses that are built over top of them, and take a significant amount of work to finish. They defend the same, but enemies cannot see units inside. Castles are immune to attacks from Siege Rams and Bunkers are immune to attacks for Air and Missile units.

Other Bases[]

There are three other kinds of military base. More info can be found on Airbases and Naval Bases by clicking the link for each base type. The last type of base is the Hideout:

  • A Hideout can be made in Forests, Swamps, Mountains, and Jungle, but not in someone else’s territory. Units in a hideout are invisible to other players. Only Foot soldiers can make Hideouts. All Land units and Helicopters can hide in them. Other types will be seen. Hideouts are not seen or detected on the map, are invisible to anyone not occupying the tile, and only appear as an activity icon near the unit who is hiding in it. The only way to see a Hideout is to have a unit inside it. Hideouts can't co-exist with other base types. Hideouts utilize natural terrain and foliage; therefore, for each turn it is unoccupied, a Hideout has a 15% chance of being lost to weather or other forces of nature; however, Hideouts made on Ruins will never disappear. Hideouts provide no bonus of any kind except for invisibility.
  • Ruins mark the site of a now uninhabited city. Units in Ruins can use the cellars, walls, and old buildings somewhat like a base. There is no defense bonus, but units in Ruins will not experience Stack-Kill.


Fighter types can Vigil - this orders them to auto-attack units who moved adjacent if and only if...

  1. The other unit is any type of airplane, or is a Paratrooper or Transport Helicopter.
  2. The fighter has greater odds to win by attacking instead of defending
    • This odds of winning must be greater than 25%.
  3. The fighter is not the only unit defending a city
    • This rule is ignored if the Fighter has a 90% or greater chance to win.

A fighter can vigil if it has not moved more than its move limit for allowing Vigil:

Fighters on Carriers can Vigil until the Carrier moves. After Carrier movement, the Vigil order must be reset.

For a quick lookup chart to see which vigil units will engage which adjacent units, please see Vigil Engagement Chart.

Pearl Harbor Effect[]

MP2 and most other rulesets have The Pearl Harbor Effect. If attacked in a city, defending firepower for Sea units is set to 1, and firepower of the attacker is doubled.

City Defenses[]

There are five buildings which improve the strength of units who are attacked inside a city:

City Defense Improvements
Fortifications Fortifications

cost:35 upkeep:0

requires: Masonry

+0.17 added to Terrain Defense on Lowlands

1.5× defense vs Land attacks* walls City Walls

cost:65 or 75 upkeep:0

requires: Construction

defense vs Land attacks*

B.coastal defense Coastal Defense

cost:65 upkeep:2


defense vs Sea attacks

Sam battery SAM Battery

cost:80 upkeep:2


defense vs Air (including Helicopters)

(not Missiles)

B.sdi defense SDI Defense

cost:140 upkeep:4


defense vs Missiles

"Nuke proof"

* Ballistic class Land units reduce the bonus: Catapult: -0.25x, Cannon: -0.50x, Artillery: -0.75x, Howitzer: -100% (ignores the bonus)

Note: the Great Wall wonder counts as City Walls. Gibraltar Fortress improves Coastal Defense.

Nuclear Combat[]

Nuclear bombs and missiles do not engage in combat like other units — they either strike a ground zero within range of an SDI Defense and are harmlessly destroyed, or detonate at a ground zero outside the range of SDI, which results in a blast area around the attacked tile. SDI only prevents detonation within its range of protection, but provides no protection from blasts after a nuclear device successfully detonated! Within the blast radius for the specific type of nuke, all units are destroyed. cities lose population, and each land tile has a 50% chance of becoming polluted with Fallout.

Nuclear Fallout raises the chances of Nuclear Winter — terrain begins changing into colder terrain; ice caps grow, which lowers sea levels. Workers and Engineers must be given the Clean Fallout command to dispose of nuclear waste. Fallout gradually disappears by itself -- roughly 15% will fade away each turn. However, be warned: the natural rate of dissipation is not fast enough to prevent nuclear winter, if the world has a lot of Fallout.

Diplomatic Combat[]

See this section in the page on Diplomacy.

Capturing Units[]

The following non-military units may be captured, which converts them into your own units:

  • Tribesmen, Workers, Peasants, Pilgrims, Proletarians, Migrants
  • Explorer
  • Caravan, Wagon, Goods, Train, Truck, Freight

To capture a unit requires a Foot soldier or Mounted unit whose raw attack value is 3 or higher. (If less than 3, the units will fight for their freedom.) Units on a tile with other units may not be captured—however, cargo Commerce units such as Goods and Freight do not count toward the number of units on the tile: commercial cargo being carried by captured units will be looted as booty and transferred to the capturer's nearest domestic city.

Units in Forts, Fortresses, or Mountains terrain may not be captured.

In Longturn games, a unit from a nation who is idle 3 turns can't be captured unless inside the capturer's territory.

Expelling Units[]

The following non-military units can be expelled from your nation, which sends them back to their home country:

  • Settlers, Well-Digger
  • Tribesmen, Workers, Engineers, Peasants, Pilgrims, Proletarians, Migrants
  • Diplomat, Spy
  • Caravan, Wagon, Truck
  • Explorer, Airplane, AWACS

Expelling is easier than Capturing. To expel a Land unit requires any Land-based military unit except Warriors. Units on Mountains terrain may not be expelled. Units on a tile with other units may not be expelled. Expelling an Airplane or AWACS requires a Fighter-type unit.

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