This article is accurate for the latest versions of EU3, Napoleon’s Ambition, In Nomine, Heir to the Throne and Divine Wind.
Diplomacy is any sort of interaction between states in Europa Universalis III that does not directly involve the military. It includes creating various kinds of treaties and alliances with friends and enemies, as well as peace negotiations which conclude wars.
The diplomatic relations between two countries are measured on a scale from -200 (worst) to +200 (best). Relations can be raised by acts such as sending gifts or accepting royal marriages, but can also be lowered by sending insults or declaring war. Relations dictate the likelihood that a nation will accept your diplomatic proposals, good relations making it more likely.
- See also: Casus belli
All diplomatic actions require 1 diplomat. Actions and details introduced in Heir to the Throne are marked with a . Actions and details introduced in Divine Wind are marked with a .
|Declare War||None||Begins a war|
|Sue for Peace||War||Negotiation menu|
|Royal Marriage||Both parties must be monarchies, same religion group||Royal marriages allow for personal unions and the spread of dynasties|
|Offer Alliance||None||Alliance created with target|
|Dissolve this Alliance||Both alliance members must be at peace||Alliance is dissolved, relations suffer|
|Issue Embargo||None||Bans target's merchants from local COT and cuts trade revenue in their COTs from issuer's provinces|
|Revoke Embargo||Have an embargo||Revokes embargo|
|Offer Trade Agreement||None (Unavailable to Merchant Republics )||Your merchants no longer compete with the target's at any COTs, -2% Trade Efficiency|
|Cancel Trade Agreement||Have a trade agreement with target||Cancels agreement|
|Offer Vassalisation||Royal marriage, military alliance, relations ≥ 190, same religion, and target at peace||Target becomes a vassal, you get 50% of their income|
|Cancel Vassalisation||None||Target becomes Independent. You lose 10 prestige.|
|Demand Annexation (Commonly called diplo-annexing)||Target must have been a vassal for 10 years, you did not annex another vassal for 10 years, relations ≥ 190||Vassal is incorporated into your nation, +1 move to Decentralisation (), -1 Stability ()|
|Proclaim Guarantee||None||Get called to arms against anyone who attacks the target|
|Send Warning||None||Get CB on target if they declare war on anybody (on your neighbours )|
|Ask for/Cancel Military Access||None||Establishes/Cancels military access, which allows you access to foreign provinces and support limits.|
|Give/Revoke Military Access||None||Gives/Revokes military access from target|
|Send Gift||Enough ducats||Increases relations with target. Cost is proportional to target's wealth|
|Send Insult||None||Lowers relations with target, gives them CB. This is the only way to end personal union as junior partner (relations must be ≤100).|
|Claim Throne||Royal Marriage||Gain CB on target, drastically reduces relations|
|Loan Offer||Enough ducats||Loan menu: allows you to set loan size, interest rate, and repayment schedule in months|
|War Subsidies||Enough ducats (but no war)||Transfers portion of your monthly income to target. In Heir to the Throne, AI will subsidise you if you fight a common enemy.|
|Sell Province||≥ 1 province||Sell province menu: allows you to set a price in 20 ducat increments. Cores are worth more, inaccessible provinces are rejected.|
|Excommunication||Papal controller, target is Catholic and has under 100 relations with Papal State||All Catholics gain Excommunication CB on target|
|Declare Crusade||Papal controller, non-Catholic target||All Catholics get Holy War CB on target, plus advantages should they declare war.|
|Invite to Trade League||Must be Merchant Republic||Targets provinces all generally trade from republic's COT|
|Ask for Trade Rights||Must be Merchant Republic||Provinces producing agreed upon trade good will trade from republic's COT|
|Expand Influence||Prestige of 10 or greater||Sphere of Influence is extended over the target|
|Bestow Imperial Grace||Be Emperor, Have at least 1 Authority||Reduce Authority by 1, raise relations with target|
|Enforce Religious Unity||Be Emperor, Have at least 1 Authority||Reduce Authority by 1, request target changes religion to Emperor religion|
If you wish to end a war, there are four basic ways to negotiate peace. Negotiations with an alliance leader will end the war with all members of the enemy alliance. Signing a peace treaty always results in a 5 year truce with all nations involved. The consequence for breaking a truce is -5 stability.
You may only annex a nation if it has been reduced to 1 province: its capital. The only two exceptions are:
- Pagan countries, which may be annexed at any size for a flat infamy cost
- Revolter nations, resulting from successful nationalist rebels, can be defeated and reabsorbed in their entirety.
This option brings up the demand tribute window. There you may make multiple demands such as indemnities or forced vassalisation.
Offer White Peace
White peace is another term for status quo ante bellum (Latin for the situation as before the war). Nothing is surrendered. Nevertheless, it is considered a marginal loss for the attacker, since they fail to achieve their goals.
This option brings up the offer tribute window. There you may offer provinces, ducats, or other concessions in order to end a war.