Imperator: Rome – Unit Composition Guide

In Imperator Rome, each military tradition group comes with a predefined unit composition that the AI will always try to stick to. You may have noticed this during gameplay, but mercenaries do the same thing based on the culture of the province they’re from. Typically, this is made up of 3 different types of units to fill the Primary, Secondary and Flanking cohorts. If you follow the recommended counter, you should be able to crush whatever culture group you’re facing.

If you want to mod any of these values, you can find them stored in “\ImperatorRome\game\common\military_traditions”.

Culture Groups

• Latin

Default AI Unit Composition
Primary: Archers
Second: Heavy Infantry
Flank: Light Cavalry

How to counter

Place any cavalry in the primary cohort (Especially heavy cavalry as they will do +50% damage to archers)

For the secondary cohort, there are two ways to beat heavy infantry. The cheap counter would be to place archers as they trade 1:1 with heavy infantry. The expensive counter is to use horse archers as they deal 25% more damage and take 25% less from heavy infantry.

For the flank, place heavy cavalry or heavy infantry. Heavy infantry wont be as effective however as they lack maneuver to properly operate on the flanks.

Culture Group Tradition Bonuses

Also +10% Army Morale

Culture Groups

• Hellenic
• Dacian

Default AI Unit Composition
Primary: Archers
Second: Heavy Infantry
Flank: Light Cavalry

How to counter

Place any cavalry in the primary cohort (Especially heavy cavalry as they will do +50% damage to archers)

For the secondary cohort, there are two ways to beat heavy infantry. The cheap counter would be to place archers as they trade 1:1 with heavy infantry. The expensive counter is to use horse archers as they deal 25% more damage and take 25% less from heavy infantry.

For the flank, place heavy cavalry or heavy infantry. Heavy infantry wont be as effective however as they lack maneuver to properly operate on the flanks.

Culture Group Tradition Bonuses

Also, +5% Army Morale and +10% Army Starting Experience

Culture Groups

• Persia
• Bactrian
• Scythia
• Aramaic

Default AI Unit Composition
Primary: Heavy Cavalry
Second: Heavy Infantry
Flank: Horse Archers

How to counter

Place heavy infantry in the primary cohort. Any other unit will do poorly vs heavy cavalry.

Place either archers (to trade evenly) or horse archers in the secondary cohort.

Place light cavalry on your flanks to beat their horse archers. Alternatively you can place camels.

Culture Group Tradition Bonuses

Also, +5% Army Morale, -30% Weight, -15% Mercenary Maintenance

Culture Groups

• Levantine
• Arabian
• Aksumite
• Nilotic

Default AI Unit Composition
Primary: Light Infantry
Second: Heavy Cavalry
Flank: Camels

How to counter

For the primary cohort, you can place just about anything except camels and light infantry. For whatever reason, camels only have a +10% damage buff vs light infantry. If you want to truly devastate them however, put horse archers in the primary cohort as they deal +25% damage and take -50%.

Place heavy infantry in the secondary cohort. Any other unit will do poorly vs heavy cavalry.

In the flanks, heavy cavalry is best vs camels. If that’s not available, then heavy infantry also works. If thats too expensive or heavy in supply weight, light cavalry is cheaper than camels and trades evenly for damage with them.

Culture Group Tradition Bonuses

Also, -15% Mercenary Maintenance, -15% Weight

Culture Groups

• Gallic
• Britannic
• Celt Iberian
• Iberian
• Germanic
• Baltic
• Gaelic
• Proto European

Default AI Unit Composition
Primary: Archers
Second: Chariots
Flank: Light Cavalry

How to counter

Place any cavalry in the primary cohort (Especially heavy cavalry as they will do +50% damage to archers)

For the secondary cohort, place cavalry or heavy infantry. Chariots perform especially terrible versus heavy cavalry and horse archers, dealing -50% damage and receiving +25% damage. So use one of those two if you want to devastate them.

For the flank, place heavy cavalry or heavy infantry. Heavy infantry wont be as effective however as they lack maneuver to properly operate on the flanks.

Culture Group Tradition Bonuses

Also, +10% Army Morale, -15% Weight

Culture Groups

• Carthaginian
• Numidian

Default AI Unit Composition
Primary: Light Infantry
Second: War Elephants
Flank: Light Cavalry

How to counter

Place just about anything except camels and light infantry. If you want to truly devastate them, put horse archers in the primary cohort as they deal +25% damage and take -50% against light infantry.

Elephants are a terrifying enemy to come up against. No unit can beat them in a fair 1v1. The unit that will perform the best is Horse archers, so place them in your secondary cohort. Alternatively you can place heavy infantry, any other cavalry, or even your own elephants and hope to God the rest of your army beats the rest so you can outflank them.

For the flank, place heavy cavalry or heavy infantry as they both do very well against light cavalry. Heavy infantry wont be as effective however as they lack maneuver to properly operate on the flanks.

Culture Group Tradition Bonuses

Also, -25% Mercenary Maintenance, -25% Mercenary Cost, -15% Weight

Culture Groups

• Aryan
• Indian
• Tibetan

Default AI Unit Compositions
Primary: War Elephants
Second: Heavy Infantry
Flank: Light Cavalry

How to counter

For your primary cohort, the unit that will perform best is Horse Archers. Elephants are a terrifying enemy to come up against. No unit can beat them in a fair 1v1. You just have to pray whatever is facing them survives until the rest of your army can outflank them. Alternatively you can bring heavy infantry or cavalry to stall time against them.

For the secondary cohort, there are two ways to beat heavy infantry. The cheap counter would be to place archers as they trade 1:1 with heavy infantry. The expensive counter is to use horse archers as they deal 25% more damage and take 25% less from heavy infantry.

For the flank, place heavy cavalry or heavy infantry as they both do very well against light cavalry. Heavy infantry wont be as effective however as they lack maneuver to properly operate on the flanks.

Culture Group Tradition Bonuses

Also, +10% Army Morale, -15% Mercenary Maintenance

Elephants are the Space Marines of Imperator Rome. They’re super expensive, super tough, and unfortunately take way too much supply. You can fit 6 light infantry in the same amount of space as a single war elephant cohort. In a big fight they’re great to throw in, but in smaller skirmishes they’re going to be easily flanked and routed. I only use them when I’ve got manpower and money to burn.

Also note, the AI does switch up the compositions slightly depending on the availability of resources. Many nations will build light infantry when they cannot access their default unit. I’ve also noticed the diodachi like to build Heavy Cavalry when they can.

If you have any questions, please feel free to leave them below or message me directly. Thanks for reading my guide.