Warfare

War between countries

When declaring war, the war declaration window will show a comparison between the armies and navies of each country. The country that declares war and the country that was declared war upon will be called the War Leaders. Allies may join each side depending on their opinion of both sides and their distance from the enemy, but only the War Leaders can receive and accept peace proposals. Allies that are already at war have a -100 acceptance and are unlikely to join the war. A country cannot declare war on a country that's on the same side in a war.

If multiple countries are on the same side in a war, each country will have a War Participation percentage, which is how much they contributed to the war. It has no effect during civil wars, but during country wars, countries will react positively or negatively to treaties that favor or do not favor them depending on how much the country contributed.

Every country has an Army Size and a Navy Size number displayed in its tooltip. Army Size is calculated based on existing regiments, manpower, and army levies that can be raised. Navy Size is calculated based on existing ships, sailors and naval levies that can be raised.

After a peace treaty, a truce is formed between the war leaders. Truces block certain diplomatic actions and give penalties if war is declared again during that period.

Types of wars

There are two possible types of wars: country wars and civil wars.

• Civil wars are wars that start when a rebellion reaches 100% progress. When a location either falls within the zone of control of an enemy fortification or is successfully sieged, it becomes owned by the enemy. Civil wars do not use casus belli, treaties or warscore and can only end in the complete surrender and annexation of either side.
• Country wars are wars started when a country declares war on another country. When a location either falls within the zone of control of an enemy fortification or is successfully sieged, it becomes occupied and usually has to become so before it can be added to a peace treaty. Country wars use casus belli, treaties and warscore.

Casus belli

Literally meaning cause for war, the casus belli is the justification a country uses for starting a war. Depending on the Casus Belli used, the type of war and the wargoal will be different. Most casus belli have to be created before they can be used, which costs 20 Spy Network. Most casus belli expire if they are not used within 4 years. Casus belli can also be created through international organization actions, situations, and other random events. War can be declared without a casus belli, but this incurs an additional cost. Each casus belli has a wargoal, which is the objective established for the war. Achieving the wargoal will grant ticking warscore over time, while not achieving it reduces warscore. When the wargoal changes status, its warscore impact is cleared.

Casus belli	War Goal	How to Obtain	Conquer cost for attacker	Subjugate cost for attacker	Max antagonism for attacker	Conquer cost for defender	Subjugate cost for defender	Max antagonism for defender	Ticking War Score modifier	Other effects
No Casus Belli	Superiority	Always Available	+50%	+30%					50%
War from Event	Superiority		+50%	+30%					50%
Subject Broke Free	Superiority		+50%	+30%					50%
Insulted Us	Superiority	From Insult diplomatic action targeting you	+50%	+30%					50%
Supported Rebels	Superiority		+50%	+30%					50%
Declined Call to Arms	Superiority	Attempt and fail to call to arms	+50%	+30%					50%
Denied Military Access	Enforce Military Access	Send military access request and get denied	+1900%	+1900%					100%
Following Through on Threat of [Province]	Take Province	Demand Unlawful Territory action	-25%	-25%					25%
Destroyed Buildings	Superiority		+50%	+30%					50%
Trade War	Superiority	Triggered by event	+50%	+30%					50%
Border Feud	Take Border	Triggered by event	-20%	-20%					50%
Religious Conformance	Take Capital	HRE member refused religious conformance	-50%	-50%					50%
Annex	Take Capital	Triggered by event	-50%	-50%					50%
Maritime Dominance	Naval Superiority	Triggered by event	+900%	+900%					50%
Destabilized Our State	Superiority	Triggered by event	+50%	+30%					50%
Livonian War	Superiority	Triggered by event	-25%	-25%		-25%	-25%		50%
Claim Timurids	Take Capital	Triggered by event	-50%	-50%					50%
Invasion of China	Superiority	Triggered by event	-50%	-50%		-40%	-40%		25%	Attacker only allowed conquest of locations in China
Restoration of Andalucia	Superiority	Triggered by event	-50%	-50%		-40%	-40%		25%
Incursion into [COUNTRY]	Superiority	Triggered by Scottish event against England	-25%	-25%					25%	Attacker can only conquer locations in the Great Britain region.
Subjugation	Take Capital	Triggered by event		-75%					50%
Anti-Piracy War	Naval Superiority	Created. Allowed against countries sending privateers to a market in your country	+900%	+900%					50%
Seize Fur Supply	Superiority	Created against tribes with provinces that produce furs. Requires modifier from event	-20%	-20%					25%
Break free from the Tatar Yoke	Superiority		+50%	+30%					50%
Claim Throne	Take Capital	Given when a ruler dies and one of the possible heirs is your family member	+100%			-75%	-75%		50%	Attacker cannot subjugate defender. Allows the 'Join Union' peace treaty.
Coalition	Take Capital	Coalition IO	-75%	-75%		+150%	+150%		50%	Adds war enthusiasm to attackers. Allows areas to be released. Adds extra antagonism reduction for defender. Disallows separate peace.
Colonial Conflict	Naval Superiority		+900%	+900%					50%
Colony War	Take Capital		-75%			-75%			50%	Attacker and defender cannot subjugate each other. Overlords are not called into the war.
Claims on [PROVINCE]	Take Province	Created. Have cores on unowned province	-25%	-25%					50%	Adds war enthusiasm
Crusade	Take Province	Curia vote from Catholic church	-25%	-25%					25%
Crush Hussitism	Superiority	Hussite Wars situation	+75%	+75%		+75%	+75%		50%
Cut Down in Size	Superiority		+50%	+30%					50%
Religious War targeting [PROVINCE]	Take Province	Created. Requires advance and defender to be part of another religious group	+20%	+20%					50%
Disloyal Subject	Take Capital	Can be created on disloyal subjects. Persists even if subject is released	-50%	-50%					50%
Disrupting Trade	Naval Superiority	Created. Allowed against countries sending privateers to sea zones adjacent to your provinces	+900%	+900%					50%
Dissolve the Tatar Yoke	Superiority	Can be created by any kingdom or empire that is part of the Tatar Yoke against the golden horde				-25%	-25%		25%
Excommunicated Ruler	Superiority	Target has been excommunicated by curia vote	-25%	-25%					25%
Expansion into the Steppes	Superiority	Created against neighboring hordes, tribes, or country with a capital in the steppe or Northern Asia regions. Requires modifier that allows this CB.	-50%			-50%			50%
Exploration	Superiority	Created against a country in a sub continent different from yours with less power projection. Requires exploration or chartered companies advance.	+50%	+30%					50%
Dubious Claims on [PROVINCE]	Take Province	Has the same requirements as the regular claim CB but appears to be disabled.	+30%		+30%				50%
Flower Wars	Superiority	Can be created by a Nahuatl country with the flower wars focus on its neighbors	+900%	+900%		+900%	+900%		50%
Force Migration	Take Capital	Created by tribes against other tribes							50%
Force into our Faction	Take Capital	Guelphs vs Ghibellines situation. Can be created against countries that are eligible to join your international organization.	+25%	+25%					100%	Allows the 'Force into our Faction' peace treaty.
Great Northern Conflict	Take Province	Given by event	-10%	-10%					25%	Attacker can only conquer location which are either neighboring locations they own, or coastal locations in the Baltic or North German region
Take Down Hegemon	Take Capital	By non-hegemon against hegemon	-75%	-75%		-75%	-75%		50%
Cleanse Heresy	Superiority	Created against neighbors of a heretic religion	+75%	+75%		+75%	+75%	100,00 %	50%
Overthrow High King	Superiority	Can be created by members of the High Kingship IO against the leader	+50%	+30%					50%
Reclaim High Kingship Land	Take Province	Created. Target province is in High Kingship IO	-75%	-75%	-75%	+100%	+100%	+100%	50%
Subjugate High Kingship Member	Superiority	Created. Target country is non-leader member of High Kingship IO	+100%	-75%	-50%	+100%	-75%	-50%	50%
Horde Expansion	Superiority	Can be created by hordes against non-horde neighbors							50%
Raiding Retaliation	Superiority		+50%	+30%					50%
Imperial Liberation	Take Capital	Can be created by the HRE emperor against non-HRE countries with HRE subjects	+100%			200%	200%		50%
Humiliate	Superiority	Can be created by an OPM to humiliate another OPM	+900%	+900%					50%
Humiliate Rival	Superiority	Can be created against rivals	+900%	+900%					50%
Conquer the Throne of France	Superiority	From Hundred Years War Situation	-25%	-25%		-25%	-25%		50%	Only allows conquest of location in the French region or from French subjects.
Defend the Throne of France	Superiority	From Hundred Years War Situation	-25%	-25%		-25%	-25%		50%	Only allows conquest of location in the French region or from French subjects.
Unify the [ILKHANATE]	Superiority	Created by an Ilkhanate claimant against other members	-25%	-25%		-25%	-25%		25%
Refuse the False Claimant	Superiority	Can be created by Ilkhanate members against claimants							25%
Shed Shackles of the [ILKHANATE]	Superiority	Can be created by non-Iranian Ilkhanate members against other Ilkhanate members	-25%	-25%		-25%	-25%		25%
Imperial Ban	Take Province	Can be created by the HRE emperor against non-HRE countries holding HRE land	-25%	-25%					50%	Attacker can only conquer locations part of the Holy Roman Empire International Organization
Imperialism	Take Country	Can be created in the age of revolutions by independent kingdoms and empires	-50%	-50%					100%
Independence	Independence	Can be created by subjects	-25%	-25%					100%
Jihad targeting [PROVINCE]	Take Province	From Jihad religious action	-25%	-25%					25%	Adds wars enthusiasm
League of the Public Weal	Superiority		+20%	+20%					50%
Lodi Claims	Take Capital								25%
Make Tributary	Take Capital	Can be created either by a steppe horde, against a steppe horde or tribe, or by a country with the modifier that allows tributaries. Can only be created against a country of a lower or equal rank.							50%	Attacker cannot conquer location or subjugate defender except for making it a tributary
Nanbokuchou	Destroy Army	From the Nanbokuchou situation	-25%	-75%		-25%	-75%		100%	Only allows subjugation of countries that are not a subject of another country.
Nationalism	Take Country	Can be created in the age of revolutions against countries of the same culture	-75%	-75%					50%
Native Subjugation	Superiority	Can be created against neighboring countries of pops. Requires advance	+50%	+30%					50%
Approved Claims on [PROVINCE]	Take Province	From parliament action	+25%		+25%				50%
Prevent Annexation	Take Capital	Granted when annexation starts	+100%	+100%		+100%	+100%		50%
Push Back Colonizers	Superiority	Created by tribes against non-tribe neighbors with colonial charters	-50%	-50%		+900%	+900%		50%
Red Turban Rebellions	Superiority	Red Turban Rebellions situation. Created by a rebel country against China	-98%	-98%	-98%	-98%	-98%	-98%	125%	Attacker only allowed conquest of locations in China. Adds a lot of war enthusiasm
Rein in the Rebels	Superiority	Red Turban Rebellions situation. Created by a China against a rebel country	-98%	-98%	-98%	-98%	-98%	-98%	125%	Attacker only allowed conquest of locations in China. Adds a lot of war enthusiasm
Regional Supemacy	Superiority	Red Turban Rebellions situation. Created by rebels against any other country in the China region	-98%	-98%	-98%	-98%	-98%	-98%	125%	Attacker only allowed conquest of locations in China
Resist Annexation	Independence	Granted when annexation starts	+100%			-75%	-75%	-100%	50%	Attacker cannot subjugate defender. Adds war enthusiasm
Religious Superiority	Superiority		+25%	+25%		+25%	+25%		125%	Adds a lot of war enthusiasm
Crush the Revolution	Take Capital	The Revolution situation. Created by a non-revolutionary country against a revolutionary country	-75%	-75%		-75%	-75%		50%
Spread the Revolution	Take Capital	The Revolution situation. Created by a revolutionary country against a non-revolutionary country	-75%	-75%		-75%	-75%		50%
Take Shogunate	Superiority	Sengoku Situtation. Created against the Shogun							25%
Sengoku	Destroy Army	Sengoku Situation. Created against another member of the Shogunate IO	-25%	-25%		-25%	-25%		25%
Expand Clan Authority	Destroy Army	After Nanbokuchou has ended or during Sengoku. Created by building-based clans against other clans or diamyo, but diamyo can only create against other diamyo	-25%	-75%		-25%	-75%		100%	Only allows subjugation of countries that are not a subject of another country.
Rebel Against the [SHOGUN]'s Authority	Destroy Army	Created outside of the Nanbokuchou situation by a member of the Shogunate against the Shogun.	-25%	-75%		-25%	-75%		100%	Only allows subjugation of countries that are not a subject of another country.
Reassert [SHOGUN]'s Authority	Destroy Army	Created by the Shogun against other members of the Shogunate. Disallowed during Nanbokuchou	-25%	-75%		-25%	-75%		100%	Only allows subjugation of countries that are not a subject of another country.
Slave Raiding	Superiority	Created by countries with slave raiding allowed	+900%	+900%					50%
Sound Toll Exemptions Broken	Take Capital	Sound toll exemptions revoked via diplomatic action	-50%	-50%					50%
Timur's Conquest	Superiority	Created by Timurid Empire againt any of its neighbors		-25%			-25%		50%
Trade Conflict	Naval Superiority	Created against countries embargoing the country	+900%	+900%					50%
Tribal Feud	Take Country	Created by tribes against neighboring tribes	-25%	-25%					50%
Unify China	Superiority	Created by leader of Middle Kingdom against other members	-75%	-75%	-75%	-75%	-75%	-75%	25%	Only allows conquest of location part of the Middle Kingdom International Organization
Claim Mandate of Heaven	Take Capital	Created by member of Middle Kingdom of Chinese, Confucian, Jurchen, or Mongolian culture group with less than 75 sinicized against Middle Kingdom leader	-50%	-50%		-40%	-40%		20%	Attacker only allowed conquest of locations in China
Union Independence	Defend Capital	Created by junior personal union member against the senior member							50%
Union War for Superiority	Take Capital	Created by junior personal union member against a senior member who has less than twice the great power score.	-50%	-50%					50%

Treaties

The peace treaty interface

A country can leave a war by proposing peace to the opposing war leader and the opposing war leader accepting the proposal. The country that proposes peace can choose to either enforce demands, which allows picking peace treaties that give the country a benefit, or offer tribute, which allows picking peace treaties that give the opponent a benefit. Demands and offers can target any country on the opposing side of the war. Demands will increase the antagonism of the country sending the proposition, while offers will increase the antagonism of the opposing war leader. Demands also requires the warscore to be at least 10 towards the country making the demand. A war will end when the war leaders sign a treaty, but after the war had dragged for a year countries that are not the war leader can propose peace with the enemy war leader for themselves.

Each treaty has a peace cost, which scales with the scope of the treaty. A country will only accept a peace proposal if its acceptance is higher than the peace cost. Acceptance depends on the difference in warscore, their war exhaustion, and how long the war has dragged out. In case of offering tribute, acceptance is massively decreased if the country receiving the offer would gain too much antagonism for it.

Gold can also be added to a demand or offer, which add or deduct from the peace cost. The peace cost is reduced by −10% if both countries have the same primary religion or primary culture.

Vassalizing an enemy in a peace deal will only be available when the country making demands has equal or higher country rank as the target country. In cases where the country making demands has a lower country rank, the Vassalize treaty will be hidden from the peace treaty menu.

If a treaty gives a war ally more land than they'd expect from their war contribution and the peace treaty is accepted, the country that proposed the treaty will gain Favors from the said war ally.

Treaty	Effects	Peace cost	Antagonism	Requirements

Warscore

Warscore is the value that indicates how well a country is performing in a war. A country can increase their warscore by winning battles, managing to siege enemy locations, achieving the wargoal, and establishing blockades. Warscore obtained from battles is capped to 50%. A warscore of at least 10 is required to make demands during a peace treaty.

Every location has a warscore value, which determines how much warscore it will give if occupied. Each location gives the following amount of warscore

• 2 always
• 1 has a port
• 1 is a province capital
• 5 is a country capital
• 0.25 per fort level
• 0.05 per development
• Up to 4 depending on population
• Up to 10 depending on buildings

War exhaustion

Every country has a war exhaustion, which represents how much is has been ravaged by war. If it is high enough, the country will be forced to sign a peace treaty. Each point of war exhaustion brings the following penalties:

• −2% Army morale
• −2% Navy morale
• −1% Production efficiency
• −1% Trade efficiency
• −0.03% Population growth

War exhaustion decreases by −0.1 each month while the country is at peace.

Declaring war cost

Declaring war has the followings costs:

• +10 Stability if declaring war on a country with 50+ Opinion.
• +20 Stability if declaring war on a country with 100+ Opinion.
• +40 Stability if declaring war on a country that gave military access.
• +50 Stability and +1 War Exhaustion if declaring war without a casus belli. It will also cost 20  Righteousness or  Karma if the primary religion uses the resource.
• +50 Stability, +1 War Exhaustion and +25  Antagonism if declaring war on a country with a truce. The penalties are reduced by Power Projection.

Blockade

A blockade is when a hostile navy is present in the sea zone adjacent to a port. How large the navy has to be depends on each ship's Blockade Capacity and the population, development, exports, and imports of the port locations.

The most important effects of blockade:
• Reduce Food Production
• Reduce Maritime Presence
• Reduce Development
• Reduce Control
• Reduce Prosperity

Privateering

Privateers are pirates which are paid by a country to stay in an area and will only target countries that are at war with it. Hiring privateers requires either certain  Piracy Law policies or the Letters of Marque generic advance but can also be unlocked through some country-specific advances or reforms. Hiring privateers costs 250  Sailors, but this can be reduced by a few advances. All countries adjacent to the selected area will lose 25  Opinion with the country that hired the privateers.

Initial wars

There are three existing wars when the game starts:

War	Wargoal	Attacker	Attacker allies	Defender	Defender allies
Moroccan-Tlemceni War	Take Tlemcen	Morocco	Tafilalt	Tlemcen
Scottish Civil War	Civil War	Balliol	Isles	Scotland	Moray  Ross
The Crusade Against Lithuania	Take Vilnius	Teutons	Chełmno  Courland  Dorpat  Livonia  Ösel  Pomesania  Riga  Riga Lettoniae  Samland  Warmia	Lithuania	Drutsk  Novogrudok  Pinsk  Polotsk  Rzhev  Slutsk  Toropets  Turov  Vitebsk

References

Mechanics