The diplomacy screen is an important feature of Europa Universalis: Rome, where you can interact with other nations.
Nation List
From the Achaean League to Vaccaei, each active nation is shown on the list along with their flag, current relation, and treaty status.
The relation is a number ranging from -200 to 200, which gradually shifts over time depending on the envoy's diplomatic skill, cultural difference, and any current treaties with the target. Getting the relation past 100 requires extraordinary effort beyong regular activity.
The ties show which treaties are in effect, including trade routes, alliances, vassels, and warfare.
Nation Information
Clicking on a nation shows details, starting with the government type, the ruler, their current stability, manpower, gold and research, their national ideas and selected omen.
Their infamy is also shown (being an honorable reputation if their infamy is close to zero), along with their technology level.
Below shows detailed information about their relations, whom they are allied with, their rivals, and their current mission.
At the bottom is the Take Action buttom
Taking Action
When taking action, an envoy is automatically chosen from a list of characters, although you can manually pick one.
You can make one diplomatic action for a given country every 30 days. The chance of success is based on the diplomat you send, although some options may be unavailable if there's a special requirement, or even if the senate refuses to accept it.
Declare War
Declaring War initiates hostilites with another nation. You can declare war on any nation as long as you aren't allied with them, and doing so allows you to move armies into their territory for conquest.
Declaring War does have a few items of note:
- Without a casus belli (obtained when the other nation does an act worthy of war), you lose 2 stability. This can be recovered, but it's somewhat significant cost. Additioanlly, the sudden loss of stability can trigger immediate rebellions.
- Declaring war on a country where to which you have good relations will destabilize your country. The amount also increases if you are receiving tribute from them, if they're granting military access, and so on.
- The enemy may sometimes attempt to imprison or execute the diplomat sending the declaraion of war.
Declaring war is always successful.
Sue for Peace
If you've had enough of war, you can sue for peace.
There are four major options for suing for peace. The first, annex, is only available if you captured all provinces of the nation, and if the warscore cost of the provinces isn't too high. The third, White Peace, is a quick return to status quo with no overall change in territory.
The second and fourth options, Demand Tribute or Offer Tribute, get used if there's a victory but not a dominating one. Here, you can select which provinces are ceded, as well as a monthly and lump sum payments of currency. You can also revoke cores, which are provinces the target nation considers their true property.
When a truce is made, it lasts for a few years. There is a major stability penalty for breaking the truce, thus you should wait until it first expires if you want to declare war again. Also, even if a truce is signed, the relations between you and the target nation are still in tatters.
If the enemy gets a warscore of 100 (which involves capture of all your provinces and beating down all your armies), they can dictate the terms of peace to whatever they like, even annexation. Even without obtaining that high of a score, a country leading in the war can offer more generous terms that will destabilize the country if they are refused.
Offer Alliance
You can offer an alliance to a nation. If you do, you will create a mutual agreement to participate in each other's wars.
Alliances aren't automatically triggered. To call in allies, you need to send a call to arms as another diplomatic option.
Alliances may be dissolved just as easily.
Military Access
You can ask for, grant, or revoke military access. Military access allows moving troops through territory.
Tribute
You can demand or offer tribute. In this option, tribute is a monthly payment of gold spent each month.
A Call to Arms!
If you are at war, you can use this option to bring in other allies into the fight.
The country receiving the call will know whether it's a defensive war or one they started. They may refuse the call, but doing so causes the alliance to be dissolved, and therefore ruin relations.
Request Trade access
This option allows merchants to travel through the target nation's territory.
It is not much use in the early game, as trade is normally conducted by sea or with adjacent territories.
Support Rebels
This option attempts a rebellion.
Desecrate Holy Site
This option damages a religious site of the target, also affecting religious prestige.
Seduce Governor
This option attempts to seduce an enemy governor in an attempt to steal territory.
Create Trade Route
This creates a trade route between your province and the target nation. It is more profitable than an internal trade route.
You may find it easier to use the trade mapview (in the bottom right), which highlights provinces with an available trade route. When you click on a province, it shows an available trade route, which you can then form with one of your provinces.
Assassinate
This attempts to kill a foreign character.
Smear Reputation
This decreases the popularity of one character.
Encourage Disloyalty
This reduces the loyalty score of one forign character. A low loyalty will make the character refuse to give up command of a military army, and give a chance of revolting against the country.
Send Gift
Sending a gift simply increases relations with the target nation. The relation boost works beyond the normal limit of 100.
Barbarians
You can also negotiate with barbarisn that are attacking your country. When a barbarian enters your territory, you can select the province they're occupying, and click the barbaian icon at the bottom-right corner.
You have a few options, where you can demand their surrender, create a client state with the lands they obtained, allow them to settle, or pay them off with gold. If you won a few victories against them, they become more willing to surrender.