In Rise of Nations, units are the smallest task force that can be controlled by the player. Represented by a single individual, vehicle, or small group, units comprise a nation's population, and fulfill the roles necessary for its development and survival.
The game contains more than 200 different types of units, majority of which are the Land ones. From the Ancient Age Citizen to the Information Age Stealth Bomber, units have a wide difference in roles, abilities, and avaliability. Units also upgrade as the player advances through the ages: Some evolve into different, improved units; others change in stats and appearance while staying as the same unit as before; some others only change cosmetically.
Most units are avaliable to every nation in the game, as long as the requirements to obtain them are met: These are called standard units. Some others, however, are exclusive to a particular nation, replacing part of the standard upgrade line of other nations, with special advantages compared to the standard units they replace: These are called unique units. For example, the Greeks recruit the Companion instead of the standard Cataphract, the British have King's Longbowmen instead of Crossbowmen, the Russians recruit T-80 tanks instead of Main Battle Tanks, among several other examples.
Because of the wide variety of units in the game, players have the opportunity to create an army customized to their tastes. Military and support units require two particular resources to be created, which depends on their type. Every type requires different combinations of resources, and as more units of the same type are created, their cost rises. In addition, every unit type has particular strengths and weaknesses against another. These factors both encourage and improve the chances of victory by having, as in real history, a diverse army able to react to different situations; instead of stacking the same type of unit, a common tactic in some games of the real strategy genre.
- Main article: Military Units
Military units are the main component of a nation's army, fundamental in the defense of the nation and the conquest of rival nations.
- Main article: Infantry
- Main article: Cavalry
- Main article: Artillery Weapons
- Main article: Anti-Aircraft
- Main article: Naval Units
Naval Units roam through water and can either lead assaults on coastlines or defend invasions from the sea.
- Main article: Aircraft
Aerial units are the masters of the sky. They can defend territory and targeted buildings from assaults or invade enemy units.
- Main article: Support Units
Support units do not directly fight, but they have various abilities that augment military units and can easily turn the tide of battle.
- Main article: Civilians
Civilian units are responsible for building, managing, and collecting resources for a nation's welfare and being.