Flanking bonus and Support bonus are two types of combat bonuses in Civilization VI. They are granted to units when they are grouped together in adjacent tiles to surround the target of an attack and force the enemy to fight on more than one front, or to give support to each other during defense. In the first case this bonus is known as a "Flanking bonus," and in the second as a "Support bonus." Since Flanking bonuses can theoretically stack up to 6 times and Support bonuses up to 10 times, they can turn the tide of a battle if used correctly.
For the sake of brevity, Flanking bonus and Support bonus will be collectively referred to as "Flanking and Support" in this article.
Both Flanking and Support share quite a few similarities:
- They both are unavailable at the start of the game, and are unlocked only after researching Military Tradition.
- Land units can provide bonuses to naval units and vice versa, as long as they stay in their native elements, meaning embarked land units will follow a different set of rules.
- Each stack of Flanking or Support provides +2 Combat Strength. The theoretical limit of stacks of Flanking is 6, while Support is 10, resulting in +12 Combat Strength and +20 Combat Strength (respectively) without special bonuses that grant higher Flanking or Support.
- Units and Promotions that have higher Flanking and Support only benefit more from Flanking and Support, but are not better at providing Flanking or Support to other units. (For example, an Impi and a friendly Swordsman both flank an enemy unit; the Impi will receive a +4 Combat Strength flanking bonus from the Swordsman but the Swordsman will still receive only a +2 Combat Strength flanking bonus from the Impi.) These units and Promotions include:
- Impi (+4 Combat Strength per Flanking stack)
- Light cavalry units with Double Envelopment (+4 Combat Strength per Flanking stack)
- Warrior Monks with Shadow Strike (+4 Combat Strength per Flanking stack)
- Hypaspist (+3 Combat Strength per Support stack)
- Anti-cavalry units with Square (+4 Combat Strength per Support stack)
- Great General Georgy Zhukov raises Flanking of all land units to +3 Combat Strength per Flanking stack (50% more Flanking), meaning Impi, light cavalry units, and Warrior Monks with their appropriate Promotions will receive +6 Combat Strength per Flanking stack. Great Admiral Horatio Nelson does the same thing for all naval units.
- Both Flanking and Support are effective for and against melee attacks only, which means offensive ranged attacks will not gain Flanking and units will not gain Support when defending against incoming ranged attacks. However, all non-air military units are capable of providing Flanking and Support, regardless of their modes of attack.
- Barbarians can gain Flanking and Support once at least half of the major civilizations have researched Military Tradition.
After Military Tradition is researched, units gain the ability to provide Flanking. The attacker will gain 2 Combat Strength for each friendly unit adjacent to the target of the attack. However, there are a few rules to this:
- The attacker itself does not count for the purpose of Flanking (otherwise, every melee attack will receive +2 Combat Strength, which does not make sense). This bonus is fully stackable, meaning if you do not count the attacker and there are two more units adjacent to the targeted enemy, the attacker will gain +4 Combat Strength, three more units for a +6 Combat Strength bonus, etc.
- All non-air military units can provide Flanking, but only melee units can gain Flanking bonus. For example, you have a Warrior and an Archer both adjacent to an enemy unit (three units form a triangle). If your Warrior attacks the enemy, the Warrior will gain 2 Combat Strength Flanking bonus provided by the Archer, but the Archer will not gain any Flanking if it is the one who conducts the attack.
- Embarked land units do not provide Flanking. As mentioned above, land units can benefit from Flanking provided by naval units and vice versa, but only if they stay in their native elements. Land units on water tiles will lose the ability to provide Flanking.
- Land units still receive Flanking when they perform an Amphibious attack (an attack conducted when the land unit is on a water tile and attacks onto a land tile). Of course, unless it is a melee unit with the Amphibious Promotion, it still receives the Combat Strength penalty for performing such an attack like normal.
- Allied or neutral units do not provide Flanking - not even units belonging to two civilizations can provide Flanking to each other when at war with a common foe. Only units that are currently owned by the same player can provide Flanking to one another, which means levied units do provide Flanking during their levying period.
- Units across a River from the targeted enemy do not provide Flanking.
- Units will not gain Flanking when attacking defensible Districts (City Center, Encampment, Oppidum). However, units inside these Districts can still provide Flanking to their friends.
If the targeted enemy is surrounded by 6 land tiles, the maximum number of Flanking stacks that can be earned is 5, since the unit that conducts the attack does not count. However, the theoretical 6 Flanking stacks can be gained when at least one tile adjacent to the enemy is a water tile occupied by a friendly naval unit, and the unit that conducts the attack does so amphibiously. Basically, in that case, the enemy is surrounded by all 6 fronts, both land and water, and since the attacker attacks from a water tile with a friendly ship, all 6 tiles provide Flanking to the attack.
The easiest way to take advantage of this is to always remember to move all units into position before any of them launch an attack, so that all can benefit from the maximum Flanking possible. When your unit kills and displaces an enemy unit in an adjacent tile, it can provide Flanking to another battle one tile away from its original position, so do take that into consideration.
Similar to Flanking, once Military Tradition is researched, your units can support each other when one gets attacked. The defender will gain 2 Combat Strength for each adjacent friendly unit. Below are a few rules that apply to Support:
- Support is fully stackable; also, Support can only be provided and received by units under the same ownership.
- All non-air units can provide Support and can benefit from Support; however, Support is effective only against melee attacks. Ranged attacks ignore any Support received by the defender.
- Embarked land units provide Support like normal. Since naval units provide Support to land units and vice versa, a water tile containing an embarked unit and a naval unit provides +4 Combat Strength to any friendly unit defending in an adjacent tile.
- Embarked land units do not benefit from Support against attacks of enemy naval units.
- Similar to Flanking, only units that are currently owned by the same player can provide Support to one another.
- Units can provide Support to each other across a River.
- Units will not gain Support when inside defensible Districts (City Center, Encampment, Oppidum). However, units inside these Districts can still provide Support to their friends.
Since embarked land units still provide Support, the maximum number of Support stacks is 10, which can be earned when the defending unit is surrounded by 5 water tiles, each occupied by a friendly embarked unit and a naval unit.
To take advantage of Support, units with low Combat Strength like recon or ranged units should be placed behind the melee frontline to provide extra sturdiness. Wounded units should also be retreated to the back line to heal and provide Support to the frontline at the same time. Also, try to take out ranged units quickly if possible, since their damage pierces any Support provided to your units. Of course, it is more advantageous to get your hit in before your enemies get the chance to, but if you cannot finish the kill before your turn ends, make sure your units end their turn close to one another.