This class covers everything from your milita to your Bradley IFV's. Foot infantry tends to excel at close range fighting in built up cities so bear this in mind when building.
These units help to extend your line of sight because they have a good spotting range and a high spotting strength. However they are very limited in combat power and so should avoid getting into fights.
All your Battletank's are to be found in this class, they combine high mobility with high firepower and protection. These are best used in open areas where their inferior close quarters stats do not matter. Tank's are generally weak when attacking towns.
These are units that are dedicated to attacking armored targets such as tanks. These are weak against infantry and soft targets so they have to be used sensibly.
These are your ranged units which are not direct combatants and should not be put in the frontline if you want them to survive for any amount of time, they are best being put behind your frontline troops and they can be used to reduce enemy unit concentrations without having to directly attack them with your troops.
These are units that are designed to attack aircraft and they also have a limited ability in most cases to attack missiles. Some units are better at attacking missiles then planes so these can prove useful when defending against a nuclear strike and mass enemy airaid's.
These are a range of vehicles that are used to make up your supply services. Supply trucks can be used to transport slow foot infantry around and they can also be used to keep your units stocked up with fuel and ammo which is taken from their cargo. Bridging units are also in this class and they can be used to bridge rivers, so your troops can cross over without needing a proper bridge building.
Land units are Either Soft or Hard targets. There is much variation between the two target types in each land class.(other than tanks.. who are all hard targets)
Some land units possess special capabilities. Indicated by an Icon on their stat sheet.