War, in Humankind, is a continuation of diplomacy by force. If the other Empire is unable to or refuse to satisfy your Empire's Demands, you can resolve the argument by declaring war on the pretext of a high War Support, and crush the other Empire in combat until they abandon their own Demands and accept yours.
The War system heavily evolves around Grievance, Demand, War Support, and Reputation Badge mechanics.
War Support[]
War Support, also known as Population War Support, is the population's desire to voice dissatisfaction and wage war against a specific Empire. Your population's dissatisfaction will rise the War Support up, justify a formal war; and your population will force you to surrender if their War Support falls to 0 or take stability penalties if the war goes on for too long.
When in the Diplomacy Screen with another Empire, yours and their War Support will be shown at the top of the screen.
Similar to many other diplomatic mechanics, all the War Supports are calculated on a bilateral basis; a high War Support against Empire A will not affect relationships with Empire B.
In general, diplomatic conditions such as Grievances and Demands will increase the War Support to be higher above the equilibrium, indicating that the population of your Empire is unsatisfied with what is happening, and you can use their desire as a justification for a war. On the other hand, conditions such as Cities being ransacked and being defeated in a battle will decrease the War Support, bringing the Empire to the negotiation table or even surrender.
- Other diplomatic modifiers such as Ideological Proximity and Reputation Badges will also affect the War Support.
Every Empire's War Support has a maximum value of 100, and will gradually lean towards a base peacetime equilibrium of 50; War Support higher than 50 will naturally decrease each turn in peacetime, and vice versa.
- In addition, every signed Treaty or Alliance with change the War Support equilibrium of both Empires by -5.
- Empires that signed all the pre-Alliance Treaties with each other will both have a War Support equilibrium of 25.
- Empires that signed an Alliance with each other will both have a War Support equilibrium at 20.
- Empires that signed all the Alliance Treaties with each other will both have a War Support equilibrium of 0.
- If two Empires are in a Liege-Vassal relationship, then both of their War Support will retain the War Support equilibrium of 50, unaffected by the unique Treaties between the two.
Militarist cultures will always have a +30War Support equilibrium toward every other Empire on top of the existing War Support, as their affinity bonus.
- Militarist Empires will always have the +30War Support applied, even when in an Alliance or being a Vassal.
- Militarist Empires' base War Support is at 80 instead of 50, and their minimum peacetime War Support will normally be at 30 instead of 0.
- This means Militarist Empires can declare Formal War without Grievances or Demands.
- Moreover, forcing a Militarist culture to surrender in a war is significantly harder than forcing most of other cultures.
War Support Buildup[]
When both Empires are in Peace, War Support will naturally move towards its base equilibrium. It will increase every turn when lower than the equilibrium, and decrease every turn until reaching the equilibrium when it is higher than the equilibrium. If the equilibrium is 0, then War Support won't increase naturally.
On the other hand, when there are on-going Grievances and Demands, or someone breaks a Treaty, the War Support will increase; and most of these modifiers can stack. Since there are very few ways to decrease War Support in large numbers (signing Treaties would only decrease War Support equilibrium instead of War Support value), there will be gradual buildup of War Support over time, as long as Grievances and Demands are present.
List of War Support Modifiers When in Peace[]
| Modifiers | Value | Note |
|---|---|---|
| Being a Militarist culture | Always +30 | Will disappear when picking a different affinity |
| below equilibrium value during Peace | +2 per | Will stop once reaches equilibrium |
| Having active Demands (Religion has Reject Luxury tenet) | +1 per per Demand | |
| Having more on-going Demands than the other Empire | +3 per | |
| Grievance triggered | +5 per Grievance | Renouncing a Grievance won't cancel out the increased |
| Demanding a Demand (Religion has Reject Luxury tenet) | +10 per Demand | |
| Demand withdrawn (when Ideological Proximity is at Distrust) | +5 per Demand | |
| Demand withdrawn (when Ideological Proximity is at Toleranace) | +10 per Demand | |
| Demand withdrawn (when Ideological Proximity is at Kinship) | +15 per Demand | |
| Demand refused by the other Empire | +10 per Demand | |
| Accepted Demand from other Empire | +10 per Demand | |
| Treaty broken by the other Empire (when Ideological Proximity is at Distrust) | +5 per Treaty | |
| Treaty broken by the other Empire (when Ideological Proximity is at Tolerance) | +10 per Treaty | |
| Treaty broken by the other Empire (when Ideological Proximity is at Kinship) | +15 per Treaty | |
| Opponent retreating | +5 per retreat | Happens when the Military Accords Treaty of both Empires is at Tolerate Skirmishes |
| Recent victory in battle | +8 per victory | |
| Opponent retreating (Religion has Hunt the Infidels tenet) | extra +10 per retreat | |
| Recent victory in battle (Religion has Hunt the Infidels tenet) | extra +10 per victory | |
| above equilibrium value during Peace | -1 per | Will stop once reaches equilibrium |
| Army retreating | -5 per retreat | Happens when the Military Accords Treaty of both Empires is at Tolerate Skirmishes |
| Recent loss in battle | -8 per defeat |
Declaring War[]
The gradual War Support buildup in the peacetime implies that the population of your Empire become more and more dissatisfied with the other Empire, or vice versa. When War Support reaches a certain "boiling" point, a war against the other Empire can be justified.
War can be declared in Relation Tab using Surprise War button or Declare War button.
Surprise War[]
If you absolutely must have war, so be it.
Surprise War, as its name implies, can be declared without any proper War Support buildup - that is, without any Grievances or Demands in the first place. Surprise War can be declared via Surprise War button.
- A Surprise War only needs 20 or higher War Support.
- This means, once the War Support reaches its normal equilibrium, it would be possible to declare a Surprise War.
On the other hand, this "convenient" way to declare war is not without downside:
- Whoever declared a Surprise War, will receive an additional -2War Support per turn penalty - called Declaring Unjust War - during the war.
- In addition, for every Surprise War declared, you will receive 1 level of Traitor Reputation Badge.
- The Badge will be effective for at least 10turns, and in this period, your opponents can earn more War Support when they win a battle against you.
- The Badge will also deteriorate all the other Empires' Attitude towards you.
Basically, whoever declared Surprise War will be likely to lose War Support quicker than their opponents.
Formal War[]
Resolve this argument by force; crush the other Empire's War Support until they abandon their Demands and accept yours.
The Declare War button indicates declaring a Formal War without a proper War Support buildup - that is, with Grievances or unsatisfied Demands in the first place, the "formal" way to declare war.
- A Formal War needs 80 or higher War Support.
- This means a Militarist culture, with its +30 War Support equilibrium bonus, can declare Formal War without any pretext.
- In addition, Formal War can also be declared when a Demand is being refused by the other Empire.
Although Formal War requires much more War Support buildup or a demand being refused, it won't affect your relationship with a other Empires like Surprise War does.
In the War[]
When in war, all the Treaties between Empires are not applicable, so as Trade (unless Trade at war civic is enabled). Instead, a new set of war-time Treaties will be applied, indicating the breakdown of relationships in the war.
When both Empires are in war, War Support will lose its equilibrium and will not naturally increase. All the Grievances and Demands won't apply on War Support values anymore, the only way to impact War Support at this stage is on the battlefield. The maximum value of War Support is still capped at 100.
The ultimate goal in War is to drain your opponent's War Support - if an Empire's War Support falls to 0 in a war, the opposing Empire gains an option to force surrender or take stability penalties if the war goes on for too long.
List of War Support Modifiers When in War[]
| Modifiers | Value | Note |
|---|---|---|
| Being a Militarist culture | +30 | Can (only) be reduced in a war |
| Picked Seize Resources choice for Materials Procurement Civic | +30 | One-time effect. Triggers when going to war |
| Built Forbidden City wonder | +25 | One-time effect. Triggers when going to war |
| As Anti-Imperialist, winning a battle against Imperialist Empire | extra +20 per victory | Happens when one Empire chose Imperialist for Conquered Empires Civic, while the other Empires chose Anti-Imperialist Civic |
| As Imperialist, winning a battle | extra +10 per victory | Happens when one Empire chose Imperialist for Conquered Empires Civic |
| Recent victory in battle, with State Religion having Hunt the Infidels tenet | extra +10 per victory | |
| Opponent retreating, with State Religion having Hunt the Infidels tenet | extra +10 per retreat | |
| Capturing a City with Russian Legacy Trait | +10 per City | |
| Destruction of enemy Administrative Center | +10 per Administrative Center destroyed | |
| Recent victory in battle | +8 per victory | Irrelevant to killed. Every victory will receive +8 |
| Opponent retreating | +5 per retreat | Irrelevant to Army size. Every retreating Army will receive -5 |
| Damages to enemy Districts | +5 per | Can be done via Ransacking, Bombardment, or Nuclear Strike |
| Declaring war | -1 per | A generic penalty for whoever declared the war first (not Surprise War) |
| Territories influenced by opponent | -1 per | Can stack for each influenced Territory |
| Proximity state as attacker (when Ideological Proximity is at Distrust) | +1 per | Will increase War Support instead of decreasing due to distrust |
| Proximity state as attacker (when Ideological Proximity is at Tolerance) | -1 per | The most common penalty during a war |
| Proximity state as attacker (when Ideological Proximity is at Kingship) | -2 per | |
| Declaring Unjust War | -2 per | Penalty for declaring Surprise War |
| Cities occupied by opponent | -4 per per City | |
| White Peace treaty refused | -5 | |
| Damages inflicted to friendly Districts | -5 per | Can be done via Ransacking, Bombardment, or even Nuclear Strike. |
| Army Retreating | -5 per retreat | Irrelevant to Army size. Every retreating Army will cost -5 |
| Recent loss in battle | -8 per defeated battle | Irrelevant to killed. Every defeat will cost -8 |
| Loss of Administrative Center | -10 per Administrative Center destroyed | |
| Having Warrior Badge while occupying cities | -1 per occupied enemy City per level of Warrior Badge | |
| Waging war against a Pacifist Badge bearer | -1 per at level 1 Badge
-2 per at level 2 Badge -4 per at level 3 Badge |
Pacifist Badge can be obtained by proposing White Peace while having more War Support than the enemy |
Settling War[]
The War status will only end if a White Peace is accepted or one of the warring Empires Surrendered. Both White Peace and Surrender negotiations can be done in the Crisis Tab of the Diplomacy Screen.
Surrender and Forcing Surrender[]
There are two situations for Surrender:
- As long as two Empires are in a war and both of their War Supports are not at 0, an Empire can actively propose Surrender Terms to the other empire, therefore withdraw from war and satisfying the War Support of the other Empire in moderate terms.
- In this case, only the surrendering empire can propose the Surrender Terms.
- If the winning Empire chooses to refuse the proposed surrender terms, it loses 10War Support, and the surrendering empire gains 20War Support. Offering surrender has no cooldown or cost and can be repeated indefinitely in case of being refused.
- However, if one of the empire in the war had their War Supports reduced to 0, the wining empire can forcing it to surrender.
- Unlike the "active" surrender, in a forced surrender it is the wining empire that demand the Surrender Terms to the losing empire. The losing empire must accept the demanded terms as well as abandon all the existing Grievances and Demands.
- In this case, only the winning empire can propose the Surrender Terms.
- If the war goes on for too long with enemy War Support at 0 the wining Empire will take increasing stability penalties
Surrender Terms[]
The actual process of surrendering is done via the negotiation of Surrender Terms.
Whoever proposing the Terms - whether the surrendering empire in a "normal" Surrender, or the wining empire in a Force Surrender - will have a list of terms to select from. The terms will include pre-war Demands, Territories for annexation , forcing vassalization, as well as War Reparations paid in Money.
Each term in the list will cost/worth a certain amount of War Support, named as War Score in the Diplomacy Screen. War Score has an upper limit, and the terms selected shall not exceed the total War Score of the winning empire. This total War Score is calculated as such:
Total War Score of the Winning Empire = WSstart + WSend + C1 + C2 + ... + Cn
WSstart = the War Support of the Winning Empire at the moment the war started
WSend = the War Support of the Winning Empire at the turn of the negotiation
C1~n = the War Score values of cities and territories currently occupied by the Wining Empire
Basically, the more cities the Winning Empire is occupying, the more terms they can demand. The less cities the Winning Empire is occupying, the less terms the Losing Empire will receive. Both situations of Surrender follow this rule.
Eventually, when the total War Score costs of surrender Terms equal to the total War Score of the Winning Empire, the Surrender Terms can be established.
- Therefore, Surrender Terms can be understand as the process of Losing Empire trying to satisfy Winning Empire's War Support.
- This means an "active" surrender will be more favorable to the Losing Empire, as they can have the possibility to face less War Score to satisfy.
- This also means a Force Surrender will be more favorable to the Winning Empire, as they can have a much larger stock of War Score to spend.
List of Surrender Terms[]
The surrender terms and their War Score worth are as following:
| Surrender Terms | War Score Costs | Note |
|---|---|---|
| War Reparation | 5 * Winner's Current Era per 1 |
|
| Existing Demands before war | 10 per Demand |
|
| Give [Territory] | 20+ per Outpost (+1 for each district) 40+ per Attached Territory (+1 for each district) 80 per City |
|
| Become a Vassal of the winning empire | 135 per capital (base cost) 35 per city -5 per each 200 fame difference (max 120) |
|
White Peace[]
During the war, a White Peace can be proposed. It proposes that both Empires abandon their Demands, and put an end to the conflict without either being declared the victor of the war. Signing a White Peace will allow both Empires' Demands and war-time gains return to the pre-war situation.
White Peace can be only proposed when both Empires are having unsatisfied Demands, and both Empires' War Supports are not at 0.