Europa Universalis 4: Army Composition Guide (2024)

Quick Links

  • How Army Composition Works

  • Early-Game Strategy

  • Artillery Strategy

It is incredibly tempting in Europa Universalis 4 to simply recruit as many soldiers as you can, send them off into your latest war, and then hope for the best. Unfortunately, doing this is likely to get your army wiped out by more attentive players or even the AI if it's deciding to work on this particular day.

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Army composition is important in EU4. The game takes a lot of things into account when calculating the outcomes of a skirmish and knowing how to optimize your army will give you that edge when it comes to toppling your foes - especially the larger ones.

How Army Composition Works

Europa Universalis 4: Army Composition Guide (1)

The combat width tooltip in Europa Universalis 4

There are quite a few things to consider when forming an army.

  • In Europa Universalis 4, armies work as two ranks of units - a frontline and a backline. Infantry and cavalry can attack from the frontline while artillery can fire from either the frontline or the backline.
  • Your army's width is dictated by your current Military Technology level. It increases as you purchase more technology levels.
    • An army width of 20 indicates that you can have 20 units in your frontline and 20 units in your backline.
  • Infantry and cavalry take precedence in filling the front row of an army, with artillery taking the back row. This is good, as artillery units take more damage when in the frontline.
  • Every nation will have a "cavalry to infantry" ratio. If there are too many cavalry units in an army, they will suffer penalties in battle.
    • The base ratio is 50 percent, so an army with 22 units of infantry shouldn't have more than 11 units of cavalry.
    • Certain nations and government types will have better cavalry to infantry ratios and will therefore be able to field more cavalry units effectively. Notable examples include Steppe Hordes, Tribal Federations, and nations of the Sunni faith.

Early-Game Strategy

Europa Universalis 4: Army Composition Guide (2)

An Ottoman army in Edirne in Europa Universalis 4

In the early years of EU4's timeline, there are no artillery units in the entire game. As such, armies are made up of only infantry and cavalry.

Military Tech Level





Combat Width






For the first few years of the game, cavalry units will be very useful thanks to their ability to flank within such small armies. Keeping at least four cavalry units in every army will ensure that your flanks are filled with useful units and your army will really shine in the shock phase of a fight. This is just a rule-of-thumb, however.

Artillery units are unlocked at level seven, which is when you should start shuffling your army compositions around to include them.

Artillery Strategy

Europa Universalis 4: Army Composition Guide (3)

Some Ottoman artillery units in Constantinople in Europa Universalis 4

Once cannons are unlocked, things change rather drastically.

Military Tech Level










Combat Width










With a Military Technology level of nine, you will have a combat width of 25. This means that you can fill your front row with infantry and cavalry, while also filling your back row entirely with artillery.

Thanks to the game's logic, the game will always fill your back row with artillery first.

  • Since artillery takes double damage in the front row, make sure that the number of artillery units you have in an army does not exceed the total number of infantry and cavalry units combined.
  • For cheaper armies, it is absolutely possible to get by with only two units of cavalry in your entire army. Flanking is less useful as combat width increases.

There are certain technology milestones that will affect your army composition in an ideal world.

  • Having artillery in your army will grant a bonus to sieges against enemy forts. The bonus depends on both how many units of artillery you have and the level of the fort you're sieging. As a result, from Military Technology Level Seven onwards it's very useful to have a few cannons in your ranks.
  • Artillery Units will get significantly better once you hit Military Technology Level 16. From here it is a good idea to fill your entire back row with cannons if you can afford it. Before this, having cannons is no bad idea but it can be cheaper to make up the difference with large numbers of infantry.
  • While many players swear by the rule of having only two cavalry units per army once you have artillery unlocked, there are two stages where you might consider adding more:
    • Military Technology Levels 18 and 23 improve the flanking range of cavalry. At this point, it can be quite effective to have around four and six units of cavalry in your armies respectively.

Of course, what you actually end up using for your army composition will depend on your nation, your ideas, and your personal preferences for each army. You may wish to have a dedicated siege army for busting down forts in the early stages of the game, or you may favor horses for the entirety thanks to certain bonuses to their combat ability, for example.

Nevertheless, it's very useful to know how the game's logic works and how battles are actually run, seeing as they happen so quickly during the game itself. Keeping an eye on your army width and taking some time to readjust the makeup of your armies is a small chore that can pay dividends.

NEXT: Europa Universalis 4: Burgundian Inheritance Guide

Europa Universalis 4: Army Composition Guide (2024)


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