This article will describe the intricacies of combat and combat-related activities in Civilization VI. War and fighting has always been part of human civilization, and is integral to the game. Combat in Civilization VI follows most of the guidelines from Civilization V: Gods & Kings and Civilization: Beyond Earth, but there are some important differences, which will be described at length below.
- 1 Creating military units
- 2 Combat statistics
- 3 Engaging in combat
- 4 Strategic breakdown of units
- 5 Pillaging
- 6 See also
- 7 References
- 8 Related achievements
Creating military units
Units are, of course, created in cities, either by producing them in the main Production queue, or by purchasing them with Gold or Faith (which is only possible under the Theocracy government, or in Rise and Fall with a Grand Master's Chapel built in your Government Plaza). The main difference from previous games is that not all cities may automatically produce all units anymore.
There are now Districts specialized in training/building specific classes of military units:
- Encampment - specialized in land units
- Harbor - specialized in naval units
- Aerodrome - specialized in air units
Air units may only be produced in cities with an Aerodrome. Naval units may be produced both in cities founded on coastal tiles, and in inland cities which have constructed a Harbor. Land Units may be produced in all cities, unless they have a strategic resource requirement. In this case, and if you have only 1 count of the relevant resource, only cities with the relevant specialty district may produce them (so, cities with an Encampment for land units, and cities with a Harbor for naval units, regardless of whether or not they're founded on the Coast). If, however, you have access to 2 or more counts of the resource you may produce units in any city (for example, any city with or without an Encampment for land units, and cities on Coast with or without a Harbor for naval units). Again, air units may only be produced in a city with an Aerodrome, regardless of how many counts of strategic resources you have. In Gathering Storm this distinction is not valid anymore - all land units may be produced in every city, and naval units may be produced in Coastal cities or in these with a Harbor, if you have enough of the necessary Strategic resource accumulated. Air units may still be produced only in cities with an Aerodrome.
Combining units (Formations)
- Corps or Fleet, created by combining two units of a kind. Requires the Nationalism Civic. The effect is to increase the Combat Strength by +10 (both Combat and Ranged Strength) as well as the Anti-Air strength by +7 above a single unit of the same type. Other statistics, such as Movement or Range, as well as Aircraft slots (Carrier), remain unchanged.
- Army or Armada, created by combining three units of a kind. Requires the Mobilization Civic. The effect is to increase the Combat Strength by +17 (both Combat and Ranged Strength) above a single unit of the same type. However, the Anti-Air strength is still only +7.
Note that the increase in CS for land formations is preserved when they embark. This benefit will only serve them for defense, since embarked units can't attack at sea. Even then, this is a considerable advantage over "normal" embarked units and could mean the difference between surviving a sea crossing under enemy fire, and sinking to the bottom.
You have two ways of forming these stronger units:
Combining existing units
Whenever you have two or more identical combat units in adjacent tiles, a special action will appear in their Action tab. Selecting this action will prompt you to choose a unit with which to combine. The act of combining the units will absorb the targeted unit from its tile, and create the new, stronger unit in the original tile (this can be used to strategically retreat units that have already acted).
Aside from receiving a combat bonus, when two units are combined into a formation the following happens:
- the Level and number of XP points of the more experienced unit is kept
- the unique name of the more experienced unit is kept
- the unit HP is averaged between the separate units
- all promotions are combined (Gathering Storm update) - great for combining units with separate promotion tree choices
- the highest combat experience modifier is kept (Gathering Storm update) - great for improving the XP rate of older high level units by integrating new highly trained ones; this also allows cities without an Encampment or Harbor to contribute to a skilled military
Note that it is not possible to combine City State units (with your units or within themselves).
Note that GDRs in Gathering Storm are the only units which cannot combine into Formations.
- Corps or Fleet: 150% unit Production/ Gold cost, double strategic resource cost
- Army or Armada: 225% unit Production/ Gold cost, triple strategic resource cost
However, it is still faster than creating two or three separate units, then combining them (unless of course you create them in two or three different cities).
Gold maintenance for the combined units is less than the combined value of the two or three units:
- 100% base unit
- 150% Corps/Fleet
- 200% Army/Armada
In Gathering Storm the resource maintenance cost for a formation unit remains 1, regardless of its being a Corps or Army. This allows civilizations with less access to Strategic resources to still field a strong army, because they may keep producing units and combining them into stronger formations while still fitting into their resource cap.
Shaka and the Zulu have special benefits to Corps and Armies: not only can they be created faster, earlier, and cheaper, but they also have some significant advantages in combat. Read more in the Strategy sections of those pages.
The combat statistics system is largely unchanged from Civilization V: Gods & Kings. Each military unit possesses statistics which describe its strength in combat. This strength may be modified further by factors such as promotions, terrain bonuses or other special bonuses. There are several statistics important to combat:
- Health - Each military unit has 100 points of health (even Corps and Army units). Each attack it suffers brings its health down, with more powerful attacks causing a greater loss of health. When its health reaches 0, the unit dies. Health is often abbreviated "HP" (which stands for "Health Points" or "Hit Points").
- Combat Strength (CS) - This defines the general strength of the unit. For melee units this comprises both its offensive and defensive power; for Ranged units it only comprises its defensive power (used only when it is attacked).
- Ranged Strength (RS) - Only ranged types of units have this stat. It defines the unit's power when attacking from afar. Note that this power is significantly reduced when attacking City Defenses and naval units.
- Bombard Strength - Only siege units have this stat. It defines the damage they do to Fortifications/City and District defenses. Units with Bombard Strength do significantly reduced damage versus land units, but full damage to City Defenses and naval units. Note that a ranged unit has either Ranged or Bombard Strength; it cannot have both!
- Range - Again, only ranged, siege, immortal, and some recon units have this stat. It defines which tiles around the unit's position they may attack. For example, a Range of 1 means the unit may only attack the surrounding tiles; a Range of 3 means that the unit may attack all tiles up to three away from its position.
- Movement Points (MP) - Movement points are consumed when units are directed to move across terrains and perform actions. The default consumption is 1 point per tile on plains and water which may be modified by roads, hills, river crossing, enemy zone of control, etc. Units may only attack if they have enough MPs left to do so. Strategically, high movement points means greater defense coverage of territory holdings by fewer units.
- Sight - This denotes how many tiles around its position the unit is able to "see" (that is, remove the "fog of war" from). Generally units have a sight of 2. Again, although not strictly a combat stat, this is very important, especially for ranged units.
Units may use many modifiers in combat, according to the combat situation on the ground, and the special abilities they have acquired. One big difference from older games is that all these bonuses confer direct increase or decrease to the unit's combat statistics, instead of a percentage increase. Thus, for example, a Flanking Bonus will increase the unit's CS by 4, and not by 10% anymore. This may not seem like a big change, but the odds of a battle hold in the strength difference and not in the strength ratio between the opponents like Civ V.
The term "modifiers" is technically more accurate than "bonuses," because they may be both positive and negative. Modifiers of different types may stack, vastly increasing (or diminishing) a unit's final combat statistics, thus it is perfectly possible (and quite realistic) that two otherwise equal units (from the same type, Era and experience) may have quite different combat statistics.
Below is the list of combat modifiers:
Various terrain types offer bonuses or penalties to defense. The unit which benefits or suffers is the unit currently occupying the tile. Mouse over any tile and you will see its modifiers listed in the popup info tab.
- "Ideal terrain" is the positive defense modifier, offering a +3 CS bonus. Terrains that are considered ideal are Hills (any type), Woods, and Rainforests. Note that the latter two may combine with Hills, and their bonuses stack for a total of +6. In Rise and Fall, Reefs provide a +3 Defensive CS bonus for ships.
- "Unfavorable terrain" is the negative modifier, which confers a -2 CS. Terrains considered unfavorable are Marshes and Floodplains (but not Oases). A Marsh could be found on Floodplains, and in this case the modifier is -4.
- "River defense" is a bonus which applies when the attacking unit has to cross a River to reach the defender. Unless the attacker has a special Promotion, the defender receives a +5 CS bonus. Obviously this only affects melee attacks.
- "Amphibious attack" is any attack made by an embarked non-ranged unit to a unit or District on land. This is the most complicated type of attack and carries a -10 CS penalty. Note that Melee units may acquire a special Promotion which negates both Amphibious penalties when attacking while embarked, and River defense bonuses to the enemies when attacking over a River.
Flanking and Support
- Main article: Flanking and Support (Civ6)
These bonuses depend on the grouping and position of units on the field.
A unit gains +3 CS to defense having not used any movement points last turn or +6 CS not having used movement points for at least 2 turns. This bonus will cap at +6 even when your units fortify for longer than 2 turns. Forts and Fort-like improvements instantly grant units on them 2 turns of fortification, even though they just entered the tile!
Unit Class modifiers 
Some unit classes incur modifiers when in combat with specific targets:
- Melee units versus anti-cavalry units receive a +5 CS bonus.
- Anti-cavalry units versus light Cavalry, heavy cavalry or ranged cavalry units receive a +10 CS bonus.
- Ranged units versus City/District defenses or naval units receive a -17 RS penalty.
- Siege units versus land units incur a -17 RS penalty.
Intel on enemy movements
If your intelligence apparatus is superior to your enemy's (that is, your level of Diplomatic Visibility on him is greater than his on you), then you gain a +3 bonus for each level of difference, because you have advance warning on his armies' whereabouts and intentions. Mongolia gains +6 for each level of difference. Of course, the reverse situation is also possible.
- Main article: Promotions (Civ6)
All military units may gain promotions by acquiring Experience Points. The promotion system is different from Civilization V: Brave New World, and more akin to Civilization: Beyond Earth. Each unit class has separate promotion choices - there are no cross-class promotions anymore. Furthermore, each unit class has two separate paths towards a single, "ultimate" promotion, such as the ability to attack twice in a round.
Note that, unlike in Civilization V, units battling Barbarians (or all similar units, such as Rebels) will still earn XP after reaching level 1. However, since the battle tactics of the uncouth louts/rebel scum are always the same (unlike those of civilized combatants), all combat encounters after Level 1 will grant only 1 XP, regardless of circumstances!
Units that have lost health suffer a penalty to their Combat Strength. The lower the unit's health, the greater the penalty becomes. The formula is: -10 * (100 - HP) / 100 CS modifier rounding down 0.5 or less either attacking or defending. The maximum lost health penalty is -10 * (100 - 1) / 100 = 9.9, rounding to 10, which means a unit with 1 HP will have 10 less Combat Strength than normal.
In Gathering Storm, certain late game units require per turn resource maintenance. When your reserve is not enough to pay the maintenance of all units, they will all suffer a combat penalty - we can infer that they won't have enough fuel and power to maneuver normally and use all their weapon systems! The penalty is calculated as follows: -1 * (the number of units that spend the turn without maintenance), up to a maximum of -20. However, the defensive Anti-Air strength is not reduced.
For example, you have 5 Oil left in your reserve and have 5 Infantries and 5 Artilleries. Since 5 units will then spend their turn without maintenance, all 10 units will receive a -5 Combat Strength. Next turn when your reserve hits 0, all 10 units will receive a -10 Combat Strength.
These are bonuses only applicable in special circumstances, such as from Policy cards, Religious beliefs, World Congress resolutions or civilization-specific bonuses. Note, for example, that the difficulty level of the game applies a permanent bonus or penalty to enemy combat units!
Engaging in combat
In order for your units to engage in combat with another entity in the game, they must be at war with it. You may force an attack on another civilization's or city-state's units, and this will be considered an Act of War, automatically declaring war on this entity. However, this is highly inadvisable, because the type of war declared in such circumstances is the worst possible (Surprise War), and grants the most severe warmonger penalty. So, you should first consider the formal diplomatic options for declaring war before actually engaging in combat.
Declaration and types of war
- Main article: Casus Belli (Civ6)
At first look, declaring war is simple: you just need to enter the Diplomatic screen of the target leader, and press a button. A confirmation screen will appear, and then guns will start firing. Note that unlike previous games, Trade Routes with this civilization won't get automatically plundered; instead, they will get cancelled and your Traders will be ready for reassignment in the beginning of the next turn.
However, you can't declare war if you're Declared Friends or Allies with this nation. Furthermore, you will have to think well what type of war you want to declare! Civilization VI introduces a sophisticated system of diplomatic options for declaring a war, called Casus Belli.. As the designers say, "with the passing of time, war becomes less and less the normal state of the world." Leaders become more conscious of aggressors, and are more willing to condemn unjust wars. In terms of the game, this means two things:
- With the passing of eras, declaring a Formal or Surprise War brings higher and higher diplomatic repercussions (i.e. "warmonger penalties", or "grievances" in Gathering Storm). For example, declaring such a war in the Ancient Era brings no penalties at all, while in the Modern Era it brings egregious penalties. Note that in Rise and Fall the penalties increase with passing of individual Eras, and not the World Era! Warmonger penalties will apply a direct negative result to your relations with a Leader.
- With Civic development, more and more types of war declarations (aka Casus Belli) are unlocked. These can now be used in some situations to declare types of war which will be more or less justified in the eyes of other nations and bring lessened penalties - or in some cases, none at all. For example, Declaring a War to liberate a city you've lost to the rival civilization will bring no penalties. What's more, some leaders gain special bonuses upon declaring certain types of wars.
Differently from Civilization V, entering a city-state's territory is now forbidden unless you are their Suzerain, or you're in the very beginning of the game and they haven't developed Early Empire yet.
Attacking a unit
After hostilities have been opened, your units may engage the enemy. In order to attack an enemy unit, your unit/s must be in range of the target. For melee units, that means they must be in a nearby tile and have the means to move to the target's tile; for units possessing ranged attack it means they have to be within the number of tiles their range dictates, and have line-of-sight. Furthermore, for a melee attack to occur, the attacker unit must have enough Movement points left to be able to enter the target's tile! This is also the major difference with the previous battle system, where a melee unit was able to attack the target, regardless of where its position was, so far as it had even a fraction of a Movement point left. According to the new rules, an attacker needs to have at least so many points left as it normally takes to move onto the target's tile. This is not the case with Ranged attacks, who can attack even having a fraction of a MP left - under the new rules this is a significant strategic advantage.
A ranged attack also has to obey the line-of-sight rules - in other words, it has to be able to "see" its target. That means that there can't be obstacles in the straight line between the attacker's position and the target. Obstacles comprise terrain features, such as Forests, Jungles, Hills or Mountains. If the attacker is on higher ground (i.e. a Hill), it is able to ignore all obstacles on lower ground, including other hills. However, hills with forests or jungles on them, and Mountains are insurmountable obstacles, even for units on higher ground, since they add an additional "level" of obstacle which effectively eliminates the advantage of higher ground. Finally, any ranged unit is able to attack all tiles surrounding its position. As per the new MP requirements, ranged units may attack even having a fraction of a MP left.
Note that sometimes a ranged unit may not be able to use its full range, because it's still unable to see its target due to simple distance - there are few units with a Sight range of more than 2 tiles in the game, and some of these aren't even ranged. This changes if another unit is closer and is able to "spot" the target for the ranged unit.
Siege-type units (Catapults, Bombards, etc.) cannot attack in the same turn they move, even if they're in range of the target, unless they have acquired the Expert Crew promotion or a movement bonus (Great General, Supply Convoy, etc.).
A unit may take shelter (that is, avoid being attacked) if he enters a City Center or Encampment tile. There it is invulnerable, as long as the city/encampment stands; however, when an enemy destroys/takes the city/encampment, the unit inside will be destroyed instantly, regardless of its actual health! Civilians and Support units which are in the same tile with a Military unit are also safe from attacks, as long as the military unit stands.
When a currently selected unit is able to attack an enemy, a red target cross will appear over the enemy's tile. When an attack occurs, the Combat Strength of the attacker is compared to the CS of the defender, or if the attacker is a ranged unit, its Ranged or Bombard Strength (as applicable) is compared to the target's CS. All bonuses or penalties are taken into account, and the final difference between the two strengths determines what damage the target will suffer to its health stats. Starting from a "default" damage, if the difference is zero (that is, the attacker's strength equals the defender's), the attacker will deal progressively more damage for each point of positive difference, and the opposite for negative difference, down to a minimum of 1 (verification needed).
Note that if the attacker is a melee unit, it will also suffer damage, in retaliation to its attack! Ranged attacks don't incur retaliation.
An Attack dialogue will appear always when you mouse over an enemy unit while commanding a military unit. This dialogue shows your unit to the right, and the enemy unit to the left; both have a list of items which modify their Combat Strength and project the health outcome of the attack. Use this to determine the possible outcome of the attack, and judge whether you should attack indeed, or not! In the absence of a comprehensive list of combat bonuses, the Attack dialogue is also your all-important source of information about those.
Currently, the damage formula, according to players' research, is the following exponential equation:
- e is Euler's number, a math constant approximately equal to 2.71828.
- StrengthDifference is a result of subtraction of defending unit's strength (always Combat Strength) from attacking unit's strength (either Combat Strength, Ranged or Bombard Strength).
- randomBetween is a random multiplier between given arguments, including both ends.
A few things to note about damage calculation:
- Every strength point multiplies your damage dealt (and divides damage received) by roughly 1.041.
- For units of equal total strength the expected damage dealt to each is 30HP, reliably falling between 24 and 36.
- Only strength difference matters, which means that combat buffs are not decaying in effectiveness and are equally useful in any age (e.g. a battle between 30 and 20 units will result exactly the same as 110 vs 100 units, which makes +4 Wars of Religion policy card bonus equally effective in both situations even despite the proportional difference).
- For smaller strength differences (up to about +20) the expected difference in damage between two units is approximately linear at 2.5x the strength difference (e.g. a battle between 30 and 20 units will be expected to have a difference of 2.5x10=25HP. Damage midpoint is always skewed higher than 30 so in this case the damages dealt are 20 and 45 respectively). This is a usual rule of thumb for in-game calculations.
- Strength difference of 26+ can result in one-shot-kill and 36+ difference guarantees one-shot-kill.
- Theological Combat and City Combat damage calculation work the same way as normal combat.
- Damage of wounded units is diminished up to a half of the original strength, the formula is -10 * (100 - HP) / 100, where HP is the current HP of the unit, which means that units with 30 HP will lose 7 Combat Strength and units with 1 HP will lose almost 10 Combat Strength.
- When a unit's Combat Strength is reduced to 0 (through the Varu's and Toa's debuffs, amphibious penalty, terrain penalty, etc.), it is a guaranteed one-shot kill if it attacks or is attacked, regardless of the opponent's Strength.
Melee and ranged attack locations
As before, all battles happen in the tile of the defending unit, not the attacking unit. This is very important when calculating terrain bonuses/penalties, and in certain other situations. Melee units have to physically be able to move into the attacked tile, so if the defending unit is beyond a border the attacker cannot pass,there can be no attack at all! If the attack destroys the defending unit, the attacker will advance into the tile of the battle; in the opposite case (the attacker is destroyed), the defender will stay where it is, and the attacker will simply disappear.
Ranged attacks may happen regardless of borders. In case the attack destroys the defender, it will simply disappear, and the attacker won't move.
Zone of control
- Main article: Zone of control (Civ6)
Attacking embarked units
In a major change with respect to previous games, embarked units in Civilization VI cannot retaliate against naval melee attacks! While they will defend and suffer health loss according to the normal CS comparison rules, the attacking melee ship won't suffer any damage whatsoever. This makes naval-based invasions even more difficult and riskier than before, giving a nation with good fleet a great advantage over one without fleet, which is nevertheless trying to use the sea to attack.
Also, embarked units may not attack any other unit in the water, not even other embarked units.
Embarked melee units may attack targets on land, when adjacent to it, but they will suffer the Amphibious attack CS penalty (unless they're of the melee class and have earned the Amphibious promotion). On the other hand, land melee units in tiles adjacent to embarked units may also attack, but they will do so at full strength!
All embarked units have Combat Strength for defense purposes, regardless of their type. This strength is normalized across all units (since it is accepted that all units use the same type of Transport ship), and depends on the owner's current technological Era (not the World Era!). For example, Medieval Era embarked units have CS of 30, while in the Modern Era their CS goes up to 50.
So, it may be said that "Transport ships" have decent defense. Still, they cannot attack, or retaliate against attacks, which makes them "swimming ducks", easy pickings for enemy ships. That's why you should always take care to provide your embarked army with a good maritime escort, if you want to avoid unpleasant surprises. More than one overseas invasion has failed due to the lack of adequate maritime support!
Attacking stacked units and Priority Targeting
As mentioned elsewhere, in Civilization VI units of different types may form Escort formations by stacking in the same tile. This assures defenseless units (such as Civilians or Support units) will be defended by military units while moving in hostile areas of the map. All attacks against this tile will be absorbed by the military unit of the formation, and only after its death will the enemy be able to destroy the other defenseless units.
Some units of the Modern and later Eras, however, have the special ability to attack directly Support units - this is called Priority Targeting. It becomes active only when the unit is in range of a valid enemy formation, and permits a direct attack against the Support unit, which will harm it while leaving the Military unit unharmed. Note that you cannot instantly destroy a Support unit this way, as you can by entering its tile while it is not defended! Use this option to destroy strategically important units, such as Drones or Supply Convoys.
Units may choose to Fortify, instead of attack or move (or do anything else in this round). A Fortify stance is achieved when the unit hasn't done anything for an entire round, so if you move, then Fortify, you will not be in the stance in the end of this round, but only at the end of next round. When Fortifying, a unit digs into its current position, and gains a CS defensive bonus of 3. If the unit stays dug-in for more than 1 turn, this bonus increases to 6. Note that any action besides automatic retaliation attacks will cancel the Fortify stance. However, leveling-up or Upgrading the unit keeps the Fortify stance.
There is, as usual, a Fortify until Healed button, which will hold the unit in place until its health is fully recovered. Note that to break this stance, you will need to expressly "wake" the unit.
Unit which hasn't performed any action for at least 1 turn starts to recover lost Health. Note that Healing won't happen if a unit has used his MPs for this turn, even partially. Also, unlike Civilization V, the unit regains HP only when all other players finish their turns, and not at the end of your own turn. This difference is very important, because it means that in the first round after starting to Heal, the unit will still have only its old HP, and will be more vulnerable.
The base Healing rate is as follows:
- Normal rate - 10 HP/turn. This applies to all neutral territory.
- Friendly territory rate - 15 HP/turn. "Friendly territory" comprises your own territory, and the territory of Allied civilizations and of City-states you're the Suzerain of. It does not include nations with which you have Open Borders!
- City or District healing rate - 20 HP/turn.
- Enemy/rival territory rate - 5 HP/turn. This includes territory of nations with which you have Open Borders.
Note that ships and embarked units may only Heal in Friendly territory, unless they acquire certain promotions, are a Norwegian naval melee unit, or adjacent to Abu Al-Qasim Al-Zahwari, a Medic, a Chaplain-promoted Apostle or a Supply Convoy.
The Medic support unit increases Healing rate by 20 HP for all units on and around its tile. It becomes incredibly useful for assaulting armies, since their Healing rate in enemy territory is greatly diminished. An Apostle with the Chaplain promotion and the Medieval Era Great Scientist Abu Al-Qasim Al-Zahrawi also provide the same Healing bonus granting an early, pre-Industrial Era, maintenance-free Medic. Expending the Great Scientist lets all units receive a permanent Healing bonus of +5 HP/turn. Mamluks and Māori units in a Pā will heal +10 HP/turn.
In Civilization VI some civilian units may be captured by other civilizations and then forced to serve their interests. In order to capture a unit, you need to move your own military unit into the tile currently occupied by the target civilian - it will then switch colors and become yours. You cannot capture civilians with either a civilian, support or religious unit - only military units command enough respect (and fear) to force the enemy into submission! Note also that embarked military units cannot capture - only ships may capture on water tiles.
Settlers and Builders can both get captured, and are among the best targets for raids. Use cavalry-type units to sweep into enemy territory, grab their civilians, then defend until the captives move away! Note that captured Builders will be using the same abilities as your own; that is, you won't get access to exotic foreign tile improvements, or to such whose technology you haven't researched yet.
Note that religious units, Archaeologists, Naturalists, and Great People cannot get captured - the first can move freely through tiles occupied by non-religious units (more on that below), while the latter three retreat to the nearest friendly city. Trader units are also immune to being captured; however, their Trade Route may get plundered, which destroys the unit itself.
The Fall 2017 Update introduces a new way for Military units to attack Religious units: the Condemn Heretic action. It is no longer possible for Military units to attack Religious units directly - the latter are now on their own independent layer, which for purposes of normal combat amounts to them being in a different universe altogether. In practical terms this means that both types of units may share the same tile, enter and exit it without anything happening. However, military units now may use the special "Condemn Heretic" action whenever they're in the same tile with an enemy Religious unit to destroy it instantly! The action requires 3 MPs, just like Pillaging, and besides destroying the unit will cause the religious pressure for their Religion in nearby cities to drop by 1/2 of the usual amount. Note, however, that there won't be a corresponding rise in Religious pressure for the military unit's Religion (assuming their civ follows one)! Also note that this action may only be undertaken against units from a nation you're at War with.
Strategic breakdown of units
All military units from the different eras in Civilization VI belong to a certain class, which is most easily visible from the promotions they have access to. Each one of them has a different use and purpose.
- Recon - Swift units that can explore quickly and efficiently, but are not particularly strong in combat. They receive XP not only from combat, as is usual, but also from activating Tribal Villages and discovering Natural Wonders. Their promotions allow them to traverse difficult terrain more easily, and even become invisible and launch ambushes! A high-level recon unit with the right promotions may actually stand up to any military unit of the same Era!
As their name suggests, these are the units in the front of your lines. They are good at soaking up damage, and protecting more vulnerable units in the army. Note that sometimes both units below are described in-game as "melee", for example for the purposes of the training bonus from Agoge policy and its later replacements.
- Melee - Strong front-line units that fight in close combat. They can soak up lots of damage, and are extremely effective against anti-cavalry units. They acquire Promotions that allow them to ignore some terrain penalties when attacking, and even move faster. They are also one of the classes that may attack twice in a round, after acquiring their ultimate Promotion!
- Anti-Cavalry - Melee units designed to counter cavalry units (or tanks in later Eras). They are extremely good at defending against almost anything (even Melee units, after they acquire Promotions), and like fighting in close formation with other units.
These are highly mobile units, designed to outrun enemies, flank the enemy formations and exploit vulnerabilities in their lines. All of them have lots of MPs and are able to ignore Zone of Control, which allows them to move freely around enemy armies.
- Light Cavalry - Swift mounted skirmishers that use hit-and-run attacks. After acquiring Promotions, light cavalry may attack enemy shooters with exceptional efficiency. They can also become very good at Pillaging and Escorting units (allowing these to move as fast as the cavalry unit itself), which may be incredibly useful when settling or moving Builders to faraway cities.
- Heavy Cavalry - Powerful mounted units that hit hard and can soak up lots of damage. Heavy cavalry moves faster on flat terrain than on rough terrain (all except the Knight). They are the second class which can learn to attack twice in a round, and move after attacking! With the right promotions Heavy Cavalry become city-killers, able to sweep in the right moment and deliver enough melee damage to conquer the city!
These units deal damage from a distance, without suffering any in retaliation. They are, however, more vulnerable in close combat, so make sure to protect them with melee units. Note that any shooting unit is unable to capture cities! They can still capture or destroy enemy civilians, though, as well as activate Tribal Villages and disperse Barbarian outposts.
- Ranged - Units that specialize at dealing damage, mostly to other units (they suffer a -17 RS penalty when attacking cities and naval units). With promotions, they may become especially deadly against land units, or when occupying a District. However, even with promotions they aren't especially effective against cities.They are the last class able to learn to attack twice.
- Siege - Units meant for taking down cities, districts and naval units, not land units (they suffer RS penalty when attacking land units). With promotions, these units may overcome their ineffectiveness against land units, and become as deadly as ranged units. But their main strength is when attacking cities! They are the only land unit which may develop long range, and shoot cities from outside their defensive perimeter.
- Naval Melee - Swift ships specialists at naval combat and patrolling. They are also good when moving in formation, and against Raider type units. Naval melee units are capable of capturing Coastal cities. From the Caravel on, naval melee units develop a Sight of 3.
- Naval Ranged - Ships designed to bombard from sea. With Promotions, they may specialize against land units, other naval units, or cities (or against all of them, of course!). Ranged units can develop exceptionally long range, so as to be able to shoot cities from outside their defensive perimeter. Naval ranged ships do not suffer the -17 RS penalty against cities (still suffer against Walls like other ranged units), making them the unit of choice for naval sieges.
- Naval Raider - Ships designed to be invisible, to ambush the enemy and pillage the coastline. They may attack both naval and land units, but are much more effective against the first. Raider ships stay naturally invisible, even without Promotions, which makes them very good at sneaking in enemy territory, then wreaking havoc to their coastline by Pillaging! What's more, they are the only ship class which is able to ignore ZoC, which makes them able to easily achieve the best position for launching devastating attacks against any unit in any formation. The last upgrade of the Naval Raider class, the Nuclear Submarine, is capable of launching nukes! Naval ranged ships do not suffer the -17 RS penalty against cities (still suffer against Walls like other ranged units).
- Naval Carrier - Comprised of only one ship, the Aircraft Carrier. Each Carrier is able to serve as a base to aircraft, which makes it invaluable for invasions to other continents.
Airplanes move through the air, flying above all obstacles on land or sea, and attacking targets on the ground at will. Unfortunately, they are locked to their bases, which severely limits their freedom of movement. On the other hand, Air units are able to attack without retaliation all land units, and all naval units before the Modern Era. However, later naval units (Destroyer, Battleship and later) possess anti-air weapons and can damage attacking aircraft, while Land units may enjoy the defense of special Support unit, the Anti-Air Gun, which is quite lethal against attacking aircraft.
- Air Fighter - Aerial units to attack other aerial units, or land units. They are also capable of defending against air units, by staying on Patrol and executing Interceptions. Their range is generally smaller than Bombers, but they end up being more versatile, thanks to deployment capabilities.
- Air Bomber - Aerial units specialized in attacking on the ground (or sea, with Promotions). They are naturally good at attacking city defenses (thanks to their Bombard type of damage), but through Promotions can also become good at attacking both land and naval units. Bombers may also Pillage and deliver Nukes.
- Main article: Nuclear weapons (Civ6)
As in any Civilization game, we have nukes! Their rules are much different than Civilization V, though. Nukes are now called "nuclear devices" and are stored in a secured, undisclosed location after their production. They are launched automatically by all nuclear-capable units and buildings, whenever you decide. So, no more moving bombs and missiles around the map! In fact, the actual delivery form which the device will take is created on-the-fly, according to where you will launch the nuclear strike from.
Pillaging is back with a new twist in Civilization VI, thanks to the new district system. Military units may now pillage not only tile improvements, but also districts, with different results. Pillaging now takes 3 MPs, or a full action for units with 3 or less points (under normal circumstances); note, however, that this action doesn't terminate a unit's turn - if it has more MPs left after the pillaging, the unit may take other actions. That means that from the land units, only cavalry may pillage and continue moving afterwards - indeed, light cavalry units are specialist pillagers and may acquire a special promotion which allows them to pillage with a single MP! Ships are also good pillagers because of their many MPs, especially after technological developments.
Pillaging improvements and districts
This action can be done when a military unit moves onto a tile with an improvement or district. The plunder from pillaging varies, according to the type of thing pillaged - for example, pillaging a Campus will yield Science points! Note that pillaging doesn't heal the unit automatically anymore - this is now a function of a specific loot type; i.e. the unit will get Healed for 50 HP only if it pillages a specific improvement or district, such as a Farm, or an Entertainment Complex.
Note that pillaging a district will damage one building within this district per Pillage action (starting with the most advanced one). When all available buildings have been damaged, the district itself will be pillaged, disabling it. This means that by default, one unit can pillage a single tile multiple times!
The Encampment and Oppidum cannot be Pillaged normally - they have to be "conquered" by a melee unit, as you would a City Center. At this point the entire district and all buildings in it are automatically Pillaged, but you don't gain any yields from it. The Oppidum can still be pillaged by the Sabotage Production espionage mission.
The values of the pillage "loot" are fixed in vanilla Civilization VI and Rise and Fall. However, in Gathering Storm pillaging values scale up with the passing of time (all but the Healing values)! Thus, Pillaging will preserve its strategic uses even into modern times, allowing the aggressor nation to boost its development significantly through preying on others. Note also that since the Antarctic Late Summer Update Pillaging Improvements will not provide Science and Culture yields anymore, just Gold, Faith and Healing. Science and Culture are still available from Pillaging Districts, though. Refer to the individual lists for info on what district/improvement provides what type of loot. With a Grand Master's Chapel, pillaging improvements and districts also provide bonus Faith yields.
Pillaging Trade Routes
Trade Routes of enemies may also be pillaged. This action is commonly known as "plundering" and requires less MP than pillaging tile improvements or districts, but yields a large sum of Gold. However, simply placing a military unit in any tile of the route's trajectory is not enough anymore - you must move a military unit into the tile the Trader unit is currently in to plunder its route.
Pillaging Barbarian Outposts
Unoccupied Barbarian Outposts can be pillaged by moving a land unit over its tile or by Coastal Raid. Pillaging a Barbarian Outpost removes the outpost - no more future barbarians spawn from here - and yields 50 Gold (depending on difficulty). The yield is unscaled through research and era progression. It is also unaffected by Policy.
This is a unique action performed by the Naval Raider class units (such as the Privateer). It is basically a Pillage action performed by a sea unit to a land tile which is located near the coast. The result of a Coastal Raid is the same as a Pillage action, with the nifty difference that the pillaging ship is invulnerable to anything but Ranged retaliatory strikes. Strong naval civilizations may wage attrition wars against their enemies by not engaging directly, but instead wrecking their economy via constant raids on their coasts and trade!
Norway under Harald Hardrada is a civ specifically adept at Coastal raids: all their melee ships may perform it, in addition to raider ships! What's more, they can get Science and Culture yields from raiding certain Improvements, and even kidnap (capture, that is) Civilian units which happen to be in a vulnerable tile!
Put two units into a formation.