Europa Universalis: Rome/Military

Armies
The armies in Europa Universalis: Rome are used during warfare and for eliminating both barbarians and rebels during peacetime.

In the military overview window, you can see the army and navy maintenance settings, as well as a list of legions and navies controlled by your empire. You will also see the support limit - if you have more armies or ships greater than the support limit, the maintenance costs will increase rapidly. If you want to save money, you can drag the maintenance sliders down, at the cost of having your units weakened for a few months.

Each army should be led by a commander, preferably with a high martial value. Without a leader, said army is treated to be lead by a character with a martial score of 0, which is disastrous on both morale and casualties. You will also want to make sure your selection is loyal

Unit types
There are six land unit types, and one naval unit type. Each land unit consists of 1000 soldiers.

Militia

 * Costs 1 gold, build time 30 days.
 * Maneuver 1
 * 75% versus Heavy Infantry
 * 50% versus Cavalry
 * 25% versus War Elephants
 * 50% versus Horse Archers
 * 50% versus Archers

Militia are a cheap unit, and easily constructed. However, they are extremely weak and should almost never be used for any long-term combat.

Heavy Infantry

 * Requires Iron. Costs 2 gold, build time 60 days.
 * Maneuver 1
 * 125% against Militia
 * 120% against Cavalry
 * 75% against Horse Archers
 * 75% against Archers

Heavy infantry is strong against cavalry, but weak against archers and horse archers.

Archers

 * Requires Wood. Costs 1 gold, build time 45 days.
 * Maneuver 1
 * 200% against Militia
 * 175% against Heavy Infantry
 * 75% against Cavalry

Archers are strong against heavy infantry, but weak against cavalry.

Cavalry

 * Requires Horses. Costs 5.5 gold, build time 60 days.
 * Maneuver 2
 * 150% against Militia
 * 70% against Heavy Infantry
 * 50% against War Elephants
 * 125% against Horse Archers
 * 200% against Archers

Cavalry are strong against archers, but weak against heavy infantry.

Horse Archers

 * Requires horses. Costs 5 gold, build time 60 days.
 * Maneuver 3
 * 200% against Militia
 * 125% against Heavy Infantry
 * 75% against cavalry
 * 50% against war elephants

Horse archers are strong against heavy infantry, but weak against cavalry.

War Elephants

 * Requires elephants. Costs 25 gold, build time 360 days.
 * Maneuver 1
 * 200% against Militia
 * 75% against cavalry
 * 50% against horse archers
 * 150% against archers.

War elephants are strong against archers. They perform a slower combat against cavalry and horse archers, but have a slight advantage over the cavalry. Elephants can only be constructed in a few provinces, due to being the most rare trade resource.

Trireme

 * Requires wood, and can only be constructed at a port.
 * Costs 10 gold, build time 180 days.
 * Maneuver 5

The Trireme is the only naval unit in the game, serving both as a combat ship and a troop transport. Each trireme can transport one unit.

Mercenaries
Mercenaries are generally available in provinces that border other nations. If mercenaries are available, you can build them in the same way as normal units, and they are identified by a lighter colour in the list of units.

Mercenaries are more expensive to maintain, reinforce more slowly, but don't require spending your manpower to recruit.