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- This page deals with combat mechanics. For information on the recruitment and maintenance of armies see army. For the individual unit types see land units.
Land warfare is the deployment and maneuvering of military assets against an enemy in most cases resulting in combat between opposing armies. In EUIV most combat is land-based and, while the naval aspect of war holds importance, losing the land war is usually tantamount to defeat in general. The art of land warfare is therefore of significant importance, and it's complexities are discussed here as fully as possible.
- 1 Combat interface
- 2 Deployment
- 3 Combat sequence
- 4 Combat statistics
- 5 Terrain
- 6 Sieges
- 7 Mechanics of an Army
- 8 Strategies and tactics
- 9 See also
- 10 References
EU3 introduced a complex combat simulation with over sixty different positions for units at each side, which possibilities of units moving about and firing at their flanks, and covering holes in the line, and for reserves to enter the combat. The combat system was not as transparent to the player though, and there are actually quite a lot of the players who think its about just numbers, modifiers and dice-rolls. The interface is now more obvious, you can now see which regiment is fighting which, and who is moving where.
- Main article: Army#Composition
To maximize the effectiveness of an army, the mix of troops is of vital importance.
Combat width determines how many units can actively participate in a battle at one time. At the beginning of the game all countries start with a low base combat width. As military technology advances a countries combat width increases, allowing them to use more soldiers effectively at once. Terrain impacts the width of combat rather dramatically, so a small army can hold up a large one if they get lucky and catch them in the mountains. The Combat Width used in a battle is the highest Combat Width of any of the participants. For every 1 combat width 1 additional regiment will be placed in front and back line, if sufficient troops are available. The combat width can be increased through military technology, its base is 15. Terrain gives modifiers to the combat width for both sides as following:
- Plains, Grassland, Coastline, Desert: No Modifier
- Mountains: -66%
- Hills: -33%
- Forest: -20 %
- Woods: Unknown
combat width technology levels:
- Base: 15
- Military Tech (2): +5
- Military Tech (5): +2
- Military Tech (6): +2
- Military Tech (8): +1
- Military Tech (11): +2
- Military Tech (14): +2
- Military Tech (16): +1
- Military Tech (18): +2
- Military Tech (20): +2
- Military Tech (22): +2
- Military Tech (24): +2
- Military Tech (26): +2
The game uses an undocumented algorithm to automatically deploy land units on the battlefield, on each row for each side of the battle. Through observation and controlled experiments, the community has suggested a theory that the game seems to follow, dependent on the rough size and composition of each army.[This section's factual information is debatable. See the discussion page for more information]
NB: The player plays no part in unit deployment.
For the smaller army
- If there is not enough infantry to fill the entire first row:
- Deploy all infantry in first row.
- Deploy as much cavalry at the sides of the first row.
- If there is space left in first row:
- Deploy all artillery in the first row.
- Deploy all remaining artillery in the second row.
- If there is no space left in first row:
- Deploy all artillery in the second row.
- If there is space left in first row:
- If space left in the second row, deploy all remaining cavalry in the second row, beginning with the positions behind the cavalry in the first row and then going inwards to the artillery.
- If there is enough infantry to fill the entire first row:
- Deploy all infantry in first row, except the outer positions in the amount of cavalry available but not more than 6[this amount is made up] (3 left and 3 right).
- Deploy up to 6 cavalry in first row at the sides of the infantry.
- Deploy all artillery in the second row.
- If space left in the second row, deploy all remaining infantry in the second row besides the artillery, but leave the outer positions in the amount of cavalry available but not more than 6[this amount is made up] (3 left and 3 right).
- Deploy all remaining cavalry in the available space in the second row, beginning with the positions behind the cavalry in the first row and then going inwards to the infantry.
For the bigger army
- Deploy as much infantry in the first row as are able to attack the enemies units in the first row, except the outer positions in the amount of cavalry available but not more than 6[this amount is made up] (3 left and 3 right).
- Deploy as much cavalry as are able to attack the enemies regiments in the first row.
- Deploy all artillery in the second row.
- If space left in the second row, deploy as much infantry in the second row besides the artillery as there are positions available behind the infantry in the first row.
- If space left in the second row, deploy as much cavalry in the second row besides the infantry as there are positions available behind the cavalry in the first row.
When two warring armies meet in a province a battle will commence. A battle will last until one side is routed or annihilated.
The attacker gets +0.5 Morale upon starting a battle. This can take them above their Morale maximum but only until the end of the battle.
Combat is divided into a series of 3-day phases. Phases alternate between Fire and Shock, with the Fire phase happening first.
Units in the front make an attack at enemies straight ahead of it. If no enemies can be found straight ahead, the unit will try to attack other enemies as maneuver (range) allows. Artillery also make an attack, even if they are in the back row. They only deal 50% damage, however.
At the beginning of each phase, each side rolls a die. The result is used to determine the morale damage and casualties inflicted by that side during each of the three days of that phase.
The result is computed as following:
die result = die roll + attacking leader skill + attacking unit attack pips - defending Leader skill - defending unit defense pips - terrain modifiers
- Die roll: A random number between 0-9, rolled for each entire side at the beginning of each phase (not each day).
- Leader skill: The leader skill for that phase (Fire or Shock).
- Attacking unit attack pips: The attack pips for the attacking unit for the current phase, or Morale pips if computing morale damage. Note all units attack during every phase---here "attack" does not refer to which army is attacking.
- Defending unit defense pips: The corresponding defense pips for the defending unit.
- Terrain modifiers: Harsh terrain may give a penalty to the attacks of the attacking army.
Casualties caused by each unit during each day are computed as follows:
casualties = base casualties * attacking unit strength * attacking unit modifier * (100% + attacking unit Combat Ability) * attacking unit Discipline / defending unit Tactics
- Base casualties: Base casualties is determined by the die result according to the following table:
Die result -2 or less -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 or greater Base casualties 4 8 12 16 20 24 32 40 50 60 70 80 90 100 100 120
- Mean casualties for a particular attacker advantage (net modifier to the attacker die roll) are as follows. Marginal proportional increase is the ratio of that entry compared to the last.
Attacker advantage -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Mean base casualties 4.0 4.4 5.2 6.4 8.0 10.0 12.8 16.4 21.0 26.6 33.2 40.4 48.2 56.6 64.6 74.2 83.0 91.0 98.0 104.0 109.0 113.0 116.0 118.0 120.0 Marginal proportional increase 0.0% 10.0% 18.2% 23.1% 25.0% 25.0% 28.0% 28.1% 28.0% 26.7% 24.8% 21.7% 19.3% 17.4% 14.1% 14.9% 11.9% 9.6% 7.7% 6.1% 4.8% 3.7% 2.7% 1.7% 1.7%
- Attacking unit strength: If the attacking unit has below its maximum of 1000 men, damage will be reduced proportionally.
- Attacking unit modifier: The attack modifier from the attacking unit's technology, e.g. "Infantry Fire".
- Attacking unit Combat Ability: Any Combat Ability bonuses the attacking unit has.
- Attacking unit Discipline: The Discipline of the attacking unit. Note that Discipline does not currently help in defense.
- Defending unit Tactics: The Tactics of the defending unit.
morale damage = base casualties * 0.01 / 6 * attacking unit strength * attacking unit maximum morale * (100% + attacking unit Combat Ability) * attacking unit Discipline / defending unit Tactics
- 6 base casualties translates to dealing 1% of the attacking unit's maximum morale as morale damage. Note that the modifiers may be different.
- Attacking unit maximum morale: Note that this is the maximum morale of the attacking unit, not the current morale.
Military tactics reduces the amount of damage your troops take in combat. Military tactics is increased by Military Technology.
- Base: 0.50
- Military Tech (4): +0.25
- Military Tech (6): +0.25
- Military Tech (7): +0.25
- Military Tech (8): +0.25
- Military Tech (15): +0.50
- Military Tech (19): +0.50
- Military Tech (23): +0.50
- Military Tech (30): +0.50
Each military unit has two stats in four categories: Fire, Shock, Morale, and Maneuvers. The first set of pips are yellow for offensive, and the second set of pips are green for defensive. With the exception of Morale, every combat phase the offensive/defensive pips are used against each other to calculate the number of casualties/survivors of each combat phase. Morale's pips are used to state the rate that morale will decrease as combat ensues.
Morale is an important factor in fighting battles. Each turn of combat a unit will take a Morale hit. Once an army's overall Morale value has been reduced to zero the army will attempt to retreat. Retreat cannot happen until both a fire and a shock phase have completed, so an army that has its morale reduced to 0 before that point will be destroyed.
A unit that has its morale drop below a certain threshold is flagged as disorganized, which is indicated by a small flame next to its morale bar on the map and interface. A disorganized army is unable to start moving until its morale has recovered to a certain point.
If an army loses a battle while having low enough morale to be disorganized, they will be forced to retreat to a safer province often much further away than just one over – it could be two or three provinces from where the battle was fought. They will usually retreat to one with a high base tax value, forts, and no adjacent enemies. While retreating, it cannot be engaged in combat or be controlled until it reaches the safer province. The army also moves slightly faster, and will recover morale at a normal rate during the retreat.
After every battle is fought an army must spend some time not fighting for its morale to recover.
- A shattered army will get an extra morale bonus as it stops retreating.
- Morale is not gained while forced marching
The following contributes to the maximum morale of a nation's army.
- Army Maintenance: Ranging from 20% at minimum maintenance to 100% at maximum maintenance (multiplicative modifier)
- Defensive national ideas: +25%
- Certain unique national ideas
- Researching military technology:
- Military technology (3): +0.5
- Military technology (4): +0.5
- Military technology (15): +1.0
- Military technology (26): +1.0
- Military technology (30): +1.0
- Prestige: +20% at 100 Prestige, -20%
- Army reformer advisor: +10%
- Army tradition: +25%
- Being the Defender of the Faith: +10%
- Piety (Muslim only): +25% (at 100% Piety)
The old Combined Arms bonus that used to give +25% bonus damage in EU3 has been removed. It is now called Insufficient Support and is now a penalty. Each Technology Group has a limit of what is an effective ratio of Infantry to Cavalry. If your ratio of Cavalry to Infantry is too high, your military tactics are reduced by 25%, causing you to take more damage. The ratio is checked in mid-battle.
Cavalry/Infantry ratios per tech group:
|Icon||Technology Group||Cavalry ratio|
A unit’s effective range is determined by its Maneuver value and its strength. A unit that has 75% or more of its troop strength, they will fight at full range, if between 50 and 75%, they will fight at 50% maneuver range, and between 25% and 50% strength they will fight at 25% of their maneuver range. This is always rounded down, so a regular infantry will either have 0 or 1 maneuver range. There are technologies which increase your units’ range as the game progresses.
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Terrain is randomly selected when combat starts. The percentage chance of each terrain type is the same as the percentage of each terrain type present in the province needs verification. These percentages can be seen on the terrain map mode by hovering over the province.
- Crossing a river as the attacker will add an -1 penalty
- Amphibious landing (attacking from sea or landing directly with ships) gets a -2 penalty
When your troops enter an enemy province and are not moving into another province, a siege will begin. To progress in a siege, you need at least as many besieging troops as the enemy garrison. It does not matter which unit type the besieging units are, but only infantry can try to storm the enemy fortress. Progress in a siege will never decrease as long as attackers are continuously present; however, if all attackers leave, it will be instantly reset.
Besieging armies will always take at least 1% attrition.
A siege progresses in phases. Each phase has a base length of 30 days, modified by the defender's Fort Defense ("defensiveness" in the game files).
The mean number of phases to finish a siege for a particular starting bonus is as follows:
|Starting success %||-100.00%||-92.86%||-85.71%||-78.57%||-71.43%||-64.29%||-57.14%||-50.00%||-42.86%||-35.71%||-28.57%||-21.43%||-14.29%||-7.14%||0.00%||7.14%||14.29%||21.43%||28.57%||35.71%|
|Sieges per year||0.28||0.40||0.48||0.57||0.70||0.82||0.96||1.12||1.29||1.48||1.68||1.88||2.10||2.37||2.69||3.15||3.72||4.32||4.95||5.60|
"Sieges per year" is computed at the default phase length of 30 days.
At the end of each siege phase, a die (1 to 14) is rolled. The following modifiers are then applied:
- Siege status. The most important modifier. As the siege goes on, this bonus will increase from its starting value of 0 to a maximum of 12 depending on previous die rolls.
- Leader siege. If the attacking army has a leader, the leader's siege skill is added as a bonus.
- Leaders can have Siege, capped at 6. Getting the maximum Siege 6 with no leader Siege bonuses is possible, but the chance seems to be less than one in a thousand.
- The Inside Man event can increase leader siege by 1.
- The Engineer Corps idea (Defensive Ideas) increases leader siege by 1.
- The Army Sappers unique Idea (Netherlands) increases leader siege by 1.
- Artillery. A bonus depending on the ratio of their Artillery to the defender's Fort Level:
Modifier Artillery per Fort Level +1 Any artillery at all +2 At least 2 artillery per fort level +3 At least 3 artillery per fort level +4 At least 4 artillery per fort level +5 At least 5 artillery per fort level
- Blockade. If the province is coastal and not blockaded, a -1 penalty is applied, with an additional -1 if the defender owns the province (?)
- Fort Level. The defender's Fort Level is applied as a penalty.
- Walls Breached. A +3 bonus is applied if the defender's walls have been breached.
The highest possible starting bonus is thus +6 for the leader, +5 for artillery, and -1 for Fort Level 1 for a total of +10.
The die roll may result in an increase of the siege status, to a maximum of 12. This improves the results of future siege stages.
|5 - 11||Supplies Shortage||+1 siege status|
|12 - 13||Food Shortage||+2 siege status|
|14 - 15||Water Shortage||+3 siege status|
|16 - 19||Defenders Desert||+1 siege status, reduces garrison (?)|
|20 or more||Suggest Offer||Siege successful|
Additionally, if a 14 is rolled on the die (before modifiers), the defender's walls are breached. This applies a +3 bonus to future rolls. Walls cannot be breached more than once.
Therefore, the attacker needs at least a net +6 bonus to have a chance of ending the siege. Since siege status and Walls Breached will eventually reach their combined maximum of a +15 bonus and the maximum Fort Level is 9, only non-blockaded coastal sieges can possibly fail to eventually succeed.
The attacker may choose to storm the garrison with their infantry. This results in a speedy conclusion of the siege at the cost of 5 Military power, and usually lots of lives. The attacker loses roughly 10 times as many men as the garrison if the walls are not breached and 1.5 times as many if they are (what else affects this?). Only infantry can assault
Mechanics of an Army
- Main article: Army
When an army is exiled, a black flag will be visible over it. The regiments of this exiled army are unable to participate in combat. They must first return to a province controlled or owned by you, or board a transport ship, to reset. Troops in exile are able to march through territory of countries you do not normally have military access to.
Exile occurs when an army is still in an enemy's territory when the war ends.
An enemy's provinces can be looted marching an army of any size through them. The owner of the looting army will gain money directly into their treasury equal to the base tax of the province being looted. This amount is doubled for hordes.
A province is "lootable" if it is all of the following:
- Is an enemy owned and enemy controlled territory
- Does not have the "looted" modifier (which lasts for 6 months)
- The province does not border any province where the looter has military access (allies, agreements, a province occupied by the looter or an ally).
Exiled armies and moving armies can not loot.
Clicking the hunt rebels icon in a selected army panel will set the army to automatically travel to and fight rebel armies that appear in it's surroundings. Armies that are loaded onto ships automatically stop hunting rebels.
Strategies and tactics
- Defending territory is easier than conquering it, and the bigger the battlefield the easier it gets.
- Your enemies want to besiege and conquer your provinces.
- The more the border is fortified, the better. Higher level forts means more time to take them down, more men needed to assault/siege and more attrition.
- If the border is narrow (1/2 provinces) a March is worth building. March, Severe Winter and Scorched Earth can cause an outstanding attrition that can easily burn the enemy MP pool, especially if the province is very big.
- Sometimes they will also use hunter-killer armies to destroy your armies and protect their sieges.
- Disturbing the enemies siege will reset the siege timer. Even though damage dealt will still stay, the siege timer is the main factor in winning a siege.
- If your main army is bigger than the enemies hunter army, destroy them and then hunt the siege armies. Most of them will flee, but you can often catch them.
- If your forces are inferior to your enemies hunter army, evade them and focus on killing siege armies. This will force the enemy to split up his forces to replace the siege army.
- If the enemy is concentrating his forces in one province or in a few neighbouring ones, attacking him can be dangerous.
- But that means his armies can not move.
- Besiege his land instead, while spreading out your forces. You should be able to besiege more provinces than him.
- If he sends troops while continuing his siege, destroy this army rather then continuing your siege.
- If the forces he sends are too big to be destroyed, evade them and attack the siege armies instead.
- Use Scorch Earth on your territories.
- This will cost you a lot of tax money
- 10% attrition makes even standing in this province a deadly undertaking and will burn your enemies manpower very fast.
- Besieging such a province is practically impossible.
- Try to control your enemies movement and lure him into these provinces.
Standing or Situational Army
- A standing army contains a number of troops with this number only changing slightly, usually being near the force limit.
- A standing army has the advantage of a military deterrence. Nations which can field less troops than this army will be much less likely to attack.
- Even though the number of troops is not the only point of accessible reference for warfare capabilities, its the most obvious.
- Even when kept at low moral, a standing army will be battle ready much faster than troops which have to be recruited first.
- If revolt risk is high and rebels are spawning continuously, a standing army will most likely be cheaper than recruiting and disbanding troops repeatedly.
- Recruiting regular troops costs manpower. After the standing army is created, this reserves can refill.
- A situational army contains only small numbers of troops, and will recruit additional regiments when needed.
- Maintenance for not existing regiments is even lower than for regiments with no additional funding.
- Hostile nations will possibly misjudge the military capabilities, thus could be baited into a war they can not win.
- With Administrative ideas and Innovative ideas, cost of mercenaries are competitive to regular troops, with recruiting time extremely short and no consumption of manpower. This makes them ideal troops for this strategy.
Assessing the Enemies Strength
Correctly assessing the enemies capability for warfare is essential for good preparation and thus decisions, and there are multiple indicators which allow deducing it:
- Number of troops. This most direct indicator tells the minimum strength of a nation. Only very rarely will a nation use all available resources to conduct a total war, but the possibility still exists.
- Military technology. More troops does not necessarily mean victory. How advanced are these troops matters too.
- Tech group. Usually Western troops, especially late game, are always better than Eastern/Ottomans/Muslim group.
- Idea groups. The opponent's ideas, if focused towards the Army and/or Navy, can be decisive. Also, many nations have ideas boosting their troops (France, Ottoman Empire and so on).
For fastest sieging:
- Bring lots of artillery if finances permit.
- Siege as many provinces as is safe to do so ("carpet sieging").
- Distribute one artillery to each province being sieged---one artillery will give a +1 bonus regardless of Fort Level.
- If any artillery is left over, concentrate it with the best siege leader---in terms of successful sieges per length of time, each point of bonus is worth more than the last.
- Use a small portion of your army to lure the enemy into attacking it, then come in with your main army and crush the enemy.
- Pay attention to the terrain. While river crossing are often only a minor inconvenience, a much lower combat width due to mountains or forests can hugely shift the outcome of a battle.
- Use leaders. Even a bad one is worth using.
- As long as you are in allied territory, you can instantaneously move your leader from army to army. This way you use one good leader to virtually fight all battles, saving you military monarch points.
- Armies of relatively the same size will often retreat with no or very low morale. Often chasing them down and annihilating them is possible and should be done. Be careful however when chasing an retreating army too far - this can get you into an unfavourable strategic position.
- Attrition is deadly - your manpower is your most limited resource. Avoid it as much as possible. A 10,000 men army with 5% attrition will burn 500 men each month from your manpower pool.