|Only ground troops are able to capture planets, and nearly all planets will have standing armies that can defend against invaders or be deployed to take control of an enemies planet.
New transport ships fresh from a Home Gate or shipyard come equipped with 2 infantry units, Dreadnoughts and Stations also come with troops by default. As with all cargo, the number of troops a ship can carry is determined by the size of the ship's hull. Transports and Stations can carry the most troops, other ships can only carry four infantry or less.
Additional infantry can be trained at a planet's Barracks building. Light Infantry can be trained faster than Heavy Infantry, but are weaker in combat against other infantry than Heavy units.
All troops (Light or Heavy) that have just been trained will exit the barracks with a "Green" rank, and will naturally be weaker compared to more experienced units. After being garrisoned on the planet for a time, the infantry unit will be promoted to "Veteran" rank and receive a small bonus in attack and defense. Veteran troops are also the most common because it is the highest rank an infantry unit can achieve without being in combat.
Ranks of "Hardened" and "Elite" can only be gained through combat with enemy infantry, or directing the infantry to raze enemy structures. Although rare, these highly experience troops are more effective at capturing planets and even enemy ships.