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Шаблон:SВерсия Если государству объявили войну, то оно сразу отсылает всем своим союзникам призыв к оружию. Allies who answer a defensive call to arms will not suffer any penalties for breaking a truce, attacking nations they are in a Royalmarriage.png royal marriage with, or have good relations with.


When a nation declares war, it has the option of individually calling its allies into the fight. Allies who answer an offensive call to arms will suffer all penalties for breaking a truce, attacking nations they are in a royal marriage with, or have good relations with. The aggressor has the option of declaring each of the enemy's allies as co-belligerent or not; if not, taking that country's provinces costs double warscore and diplomatic power, but they cannot call their own allies.

Players that are fielding any call to arms from an AI nation must be very careful about these penalties. As the player will enter all wars that the AI nation is leading, this may incur severe penalties on the player, though the same mechanic could be used against the AI nations as well. Defensive call to arms are the most common culprit here because they are sent out automatically. For offensive call to arms, AI nations will only consider the player's ability to join one specific war, and will not evaluate any secondary effects that may result from the player joining all the wars on the side of the AI.


Answering the call to arms brings a nation into the war on the side of its ally as a junior partner in the conflict. Because the ally is not a war leader, it can only negotiate peace with the opposing war leader and only on behalf of itself and its vassals. This is called a separate peace and choosing to make a separate peace will give Шаблон:Effect penalty with co-belligerents. Warscore for separate peace is calculated solely from occupations and blockades and will not consider battles or ticking warscore from wargoals.

Declining a call to arms will result in Шаблон:Effect and the cancellation of the alliance, as well as a Шаблон:Effect penalty for refusing to join their war, plus Шаблон:Effect for dishonoring the alliance. Refusing a call to arms from a nation that the nation is guaranteeing will result in an additional Шаблон:Effect penalty (Шаблон:Effect if the nation also had an alliance).

Conflicting call to arms

Defensive call to arms are sent out before offensive call to arms. Due to this time delay, AI nations that are allied to both the attacker and defender in a war will always consider the defensive call to arms first. Due to there being a number of positive reasons that encourage AI nations to honor defensive call to arms, and several negative reasons that dissuade them from accepting offensive call to arms, they will nearly always join a war between allies on the side of the defender.

Call to arms of the same type are sent in the order in which the corresponding alliances are listed in the diplomacy window. This is important for determining which ally will actually join the war in the event that one doing so would prevent another from doing the same.

Avoiding call to arms

A nation can not be called at all if accepting would put it in a war against any nation it is already in a war with, either as an ally or an enemy.

AI nations will only send the player a call to arms if another AI in the position of the player would have accepted that call. A combination of the following options can be used to prevent the AI from sending an offensive call to arms:

  • Have a truce with the AI's war target
  • Have a royal marriage with the AI's war target
  • Make the AI's war target have a high opinion of the player. This is typically the easiest to achieve of all options.
  • Have low trust of the AI
  • Be in another war
  • Be far from the war target
  • Be in debt
  • Have low manpower
  • Have occupied or besieged provinces
  • Have high war exhaustion

If the player has not turned on Ironman icon.png ironman, it is also possible to avoid any call to arms with a more exploitative technique. Simply wait until the call to arms is about to expire, then save and reload the game. A pending call to arms is not saved with the game, so the AI will have to resend the call to arms.

It is not possible to be both allied with a country and hostile to it in different wars. So when attacking an ally's ally, a country can avoid the common ally being called on the defender's side by first declaring a war against a different target and calling that ally into it. For example, if both Savoy and Venice are allied with France, and Savoy wants to declare war on Venice without having to fight France, Savoy can first attack the Papal State, calling France as an ally, just to get France out of the way. Note that in this situation, however, Savoy will be unable to call any (more) allies into either war since they would be called into both.

Calling the AI into wars

Ask an ally to join a war. This action does not require a diplomat. An ally called into a war cannot call in his allies, unless it is a defensive war and the ally was named a co-belligerent by the attacker (note that the Emperor defending the empire and coalition members are always considered co-belligerents). The factors that influence an AI nation's proclivity for accepting a call to arms are

Factor Effect
Caller diplomatic skill +2 per ruler Diplomatic power.png diplomatic skill
Caller diplomatic reputation Positive: +5 per point
Negative: -5 per negative point
Trust Positive: +1 per point
Negative: -1 per point
Attitude towards caller (on offense) Defensive attitude Defensive: -30
Threatened attitude Threatened: -120
Hostile attitude Hostile: -150
Attitude towards caller (on defense) Hostile attitude Hostile: -20
Threatened attitude Threatened: -20
Attitude towards enemy (on offense) Rivalry attitude Rivalry: +40
Hostile attitude Hostile: +20
Neutral attitude Neutral: 0
Unknown attitude Unknown: 0
Threatened attitude Threatened: -40
Friendly attitude Friendly: -60
Attitude towards enemy (on defense) Neutral attitude Neutral: 0
Friendly attitude Friendly: -20
Defender is part of the empire and nation is the emperor
(calling emperor to defend HRE member)
Defensive war +30
Would be called into multiple wars -1000
Allied with target in another war -1000
Fighting in another war together -1000
Has a truce with enemy -1000
Nation is allied with target -1000
Not willing to join another offensive war until date -1000
Nation is the Holy Roman Emperor
(calling emperor against HRE member)
Emperor's opinion about HRE member (on defense) Negative: -1 per point
Accepting would destabilize nation -50 per point of Icon stability.png stability hit
Nation is in debt Offensive call to arms: -10 per month of income needed to pay off all loans
Defensive call to arms:
Defender of the Faith call to arms:
Fighting in another war -20
War exhaustion -10 per point
Prepared for War +20
Manpower low
Army strength low
Distant war

†: Actual monthly income may differ from amount reported in ledger

Among the factors that influence the AI's behavior above, nation is in debt is generally the easiest one for human players to manipulate. If an AI ally is reluctant to join a war due to debt, establishing a maximum subsidy can significantly reduce this negative factor once the ledger registers the increased income. This allows one to quickly drag the AI ally into war, and the subsidy can be cancelled immediately if there is no concern over the ally's war enthusiasm. Sending a gift before establishing the subsidy may be helpful as well, though there is no guarantee that the AI will use the gift to pay down its debt.

Ending an alliance

Dissolves an alliance with the target country if one exists. Performing this action during peace time will lower relations by -50 with said country. Breaking an alliance during wartime will incur an additional Icon stability.png -2 stability hit on top of the relation penalty.

Other relations effects of alliances

Having an alliance with a nation will lower the impact of aggressive expansion. Enemies or rivals may become outraged by a nation's actions, yet its allies will have a less severe reaction. If the nation continues to pile on aggressive expansion, even the closest friend might eventually break their alliance with a nation they consider a hostile warmonger.

Having an alliance can also affect relations with nations other than the ally. Allying with a country that other countries consider a rival will cause a Шаблон:Effect relationship penalty with all countries that consider the ally their rival.

Being allied with a nation slowly builds up trust, which is factored in most diplomatic actions. It is especially important to the AI when weighing whether or not to accept an offensive call to arms.


Основная статья: Subject nation
Vassals and personal unions experience a special non-negotiable alliance with their suzerain for the entire duration of their vassalage/union. A war on one necessarily involves the other, unless the overlord has enabled scutage.

Colonial nations can fight wars without their overlord becoming involved, so long as the war is with another colonial nation or independent Native American nation. The overlord can enforce peace to join any such war, which will also bring in the overlord of an opposing colonial nation. Colonial nations attacked by any other state automatically call their overlord in, just like vassals.

Two subjects of the same overlord may enter into a special alliance with each other. If one nation declares an independence war on its overlord, the other is called in. On success, both become independent.

Vassals, personal unions, and colonial nations can also get support for independence from independent nations. This acts as an alliance in case a subject declares an independence war against its overlord. In cases where multiple subjects are allied with one another, all nations supporting the independence of any of the allied subjects will be dragged in to the independence war against the overlord.

Protectorates are not called into their overlord's wars, but their overlord will be called to defend them if they are attacked.

If Japan has the Shogunate government type, its vassals with the Daimyo government type can declare war on each other with the Sengoku casus belli without involving Japan in the war. See the Japan page for more information.

Invite to Federation

Federations are multilateral defensive alliances available only to natives with the tribal council government. If a federation member is attacked, all members are called in. Federations are not mutually exclusive with regular alliances. The leader of a federation gets a bonus to diplomatic reputation and morale.

Support independence

Шаблон:Expansion Join the independence war of the target country's side if this country as a subject declares war against its overlord. The target must accept the offer of independence, and is unlikely to do so if it likes its overlord. If war breaks out, the support is converted to a regular alliance for the duration of the war.


A coalition is a group of a nations which band together against another nation with high Aggressive expansion impact.png aggressive expansion. They serve the purpose of containing a mutual threat: if the target nation declares war on a coalition member, or a coalition member declares war on the target, all coalition members will join the war without penalties. Note that this call to war is not triggered if a coalition member is in the war of a non-coalition member against the target nation. A coalition comes with no obligation to aid coalition members in wars that are not against the target. As a result, rivals may join a coalition to stop a mutually disliked nation, even if the rival countries would never sign an alliance. They model historical coalitions against marauding conquerors such as the seven coalitions against revolutionary France under Napoleon.

Joining and leaving coalitions

Файл:Coalition join leave.png
Opinion vs aggressive expansion modifier that AI nations held against coalition target at time of joining, leaving, switching away from, or switching to a coalition in patch 1.8. There are significantly fewer instances of nations leaving naturally since coalitions are now dissolved after war. Vertical dashed lines indicate typical threshold for joining and leaving. NOTE: Image is outdated as of Patch 1.13

Any country may choose to form or join a coalition against a target nation as long as there is no existing truce between them, the target nation is not an ally or subject of the country, and -50 aggressive expansion has been accumulated against the target nation. Only nations with the Rivalry attitude rivalry or Outraged attitude outraged attitude are likely to join a coalition.

  • Joining and leaving coalitions is an instantaneous diplomatic action with no cooldown. A nation can only be part of one coalition at a time.
  • AI nations will leave the coalition instantly if they lose a war against the coalition target. They will also leave the coalition if they no longer have rivalry or outraged attitude, and have been in the coalition for more than 2 years.
  • AI coalition nations will almost instantly lose the outraged attitude if they are in the same religious league, if they have no aggressive expansion, or have more than +50 opinion of the target nation.
  • Declaring as co-belligerent a country who is in a coalition against the attacker will call the entire coalition.
  • Attacking a prince of the Holy Roman Empire in a coalition against the attacker when the Emperor is in the same coalition will have the Emperor join as a coalition member (but still able to call allies).

Coalitions in war

  • The coalition call to arms is automatic, and will result in all members not currently at war with another coalition member instantly being part of the war, even if they have a truce with the target. There is no option to decline.
  • Each coalition has a war leader. If the coalition is attacking, the war leader is the nation that declared war. If the coalition is defending, the war leader is the nation under attack.
  • The war leader always negotiates for the entire coalition; unlike alliances, countries in a coalition cannot make a separate peace. The coalition members can only take cores in a peace deal.
  • War leaders, and the Emperor in a coalition, may call non-coalition allies into the war, but these allies are not bound by the coalition rules - they may decline the call, sign a separate peace with the enemy, and take non-cores.
  • Coalitions will be dissolved after a coalition war. This does not remove existing aggressive expansion however, so the coalitions may still reform after the truce from the coalition war expires.


  • Coalitions form easily as a result of aggressive expansion. Players should avoid expanding too much into the same area to reduce the likelihood of having a huge coalition forming against them.
  • Countries cannot join a coalition against a country they have a truce with, and a coalition is dismantled after a coalition war. Players can use this to their advantage by attacking a coalition while it is still small, dismantling it and preventing the members from joining the coalition again for a while. To reduce further coalitions against the player, they should only make demands that don't increase aggressive expansion, such as money, releasing of nations, returning of cores and humiliation.

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