EU4: Aggressive Expansion Guide (Calculator) | Europa Universalis 4

Aggressive expansion is an important concept in Europa Universalis IV that players need to understand to prevent forming a coalition and avoid being attacked.

In this YourGlobalGamer guide, we will discuss what aggressive expansion is, how to get it, and ways to avoid, lower, and manage coalitions.

Aggressive Expansion Calculator for EU4

Aggressive Expansion Calculator for EU4

What is Aggressive Expansion?

Aggressive Expansion (AE) is a modifier that players receive when they expand too much in the early or late game, which can lead to the formation of a coalition against them. When a player takes over two provinces, for example, they might have a coalition of many nations against them due to having over 50 AE. Players can see the potential for a coalition by hovering over neighboring countries in the AE map mode, which highlights the nations that can join the coalition.

AE Map Mode
AE Map Mode

There are three main modifiers that influence AE:

Regional Modifier

The game is divided into various regions, such as North Germany, South Germany, and France. When a player takes a province within their region, they will receive more AE with other nations in that region. Also, players receive 50% more AE for all neighboring or adjacent nations that follow the same religion as the player.

For example, if a Catholic country annexes Luneburg, which is a Catholic country, it will receive 50% more AE with all neighboring Catholic countries. However, players get a zero percent modifier for heretical countries, such as Orthodox or Coptic countries, and minus 50% for heathen countries, such as Sunni countries.

Cultural Modifier

Players receive 50% more AE for provinces of the same culture, and an additional 25 AE modifier for other cultures within the same culture group. For example, if a player annexes Magdeburg, which is a Saxon culture province, they will receive 50% more AE with other primary Saxon cultured nations, such as Gostlar, Turingya, and Saxony. However, they will receive zero percent modifier for unrelated cultures, such as Sorbian.

CB Modifier

Casus Belli Modifier
Casus Belli Modifier

Players receive AE based on the Casus Belli (CB) declaration they make. For instance, if they declare a conquest CB, they will receive 100% AE, while the “Devil’s Vote” CB modifier will result in 75 AE. Additionally, players receive 25 AE from the “Reconquest” CB, while they get 75 AE from the “Imperialism” CB.

How to Avoid and Lower Aggressive Expansion

One of the most important things players can do to avoid and lower AE is to have high prestige. 100 prestige means a 10 reduction in the AE impact. Also, in the Age of Discovery, players can gain the “Justified Wars” Splendor Goal, which provides another minus 10 AE impact. Additionally, the “Espionage” idea provides a minus 20 AE impact, while some nations have AE reduction modifiers in their national ideas. However, the most effective way to lower AE is to improve relations. By having better relations with other nations, players can lower their AE considerably faster.

HRE Aggressive Expansion
HRE Aggressive Expansion

Players can also lower AE by having enough administrative efficiency later in the game. They can obtain administrative efficiency from national ideas, missions, tech level, and absolutism. Every 1% of administrative efficiency reduces 1% of AE. Additionally, players can become the curia controller if they are Catholic, which reduces AE by 20%. If players take provinces from a different continent, they receive -10 flat AE. However, if they take provinces from the Holy Roman Empire, they will receive more AE with all other members of the HRE and the emperor himself.

A Cheesy Way to Lower Aggressive Expansion

There is a way to lower AE without being labeled an exploit, but it is still a controversial method among players. When a player has 100 war score against another nation, they can offer their core provinces to the enemy, except those with cores belonging to other nations. Losing many provinces leads to a lower AE modifier, allowing players to expand without worrying about the coalition.


Aggressive expansion is an essential aspect of EU4. By understanding the regional, cultural, and CB modifiers, players can manage their AE and diplomatic relations more efficiently. Avoiding and lowering AE by improving relations, having high prestige, administrative efficiency, being the Korea Controller, and releasing vassals can lead to expansion success. Managing coalitions by declaring separate wars and timing truces is also crucial. While the cheesy method of lowering AE through offering core provinces is controversial, it is still an effective way of expanding without worrying about the coalition.


  • Matthew Flores

    Matthew Flores plays games for a living... what a life! He began with World of Warcraft when he was just a young man; nowadays, he has evolved to play every genre—grand strategies, RPGs, shooters, MMOs, and everything else! With this being his passion, he dreams of sharing his 1000s of hours of knowledge and expertise with others by creating YourGlobalGamer.

Leave a Comment