Ground combat is a special sort of combat which occurs when one ship drops its cargo of colonists onto an occupied planet. Please note that, if two ships drop colonists on an unoccupied planet (or one occupied by a third party) in the same turn, the drops take place in ascending order according to Ship ID number. In that event, each succeeding surviving assault wave is considered the Attacker when it is being dropped and the Defender when it is being dropped upon.Certain races have a default advantage in ground combat, as follows:
In addition to the racial modifiers, every 20 defense posts on a planet add a defense factor to defending colonists on that planet. (100 defense posts would increase a planet's defense factor by 5.) These are additive with racial modifiers. This means 1 defending clan on a planet with 60 Defense Posts would kill 4 unmodified attacking clans.
If a ground attack is successful, all planetary structures (including defense posts) remain intact, and any orbiting starbase changes hands as well.
An Imperial Assault is a special case of ground attack that bypasses defense posts, destroying them in the process; 10 or more attacking troops from a Super Star Destroyer will automatically defeat all defending colonists. This takes place during the same Host phase as all other ground attack, so depending on Ship ID numbers, it's entirely possible that an Imperial Assault force will be attacked and wiped out in turn.
If it should happen that, at any point during the turn, the planet is reduced to 0 Colonists, any orbiting starbase will be destroyed. If either the attacker or the defender has survivors, however, it too will survive and serve the victor.
When a planet is taken with ground combat of any kind, the Friendly Code of that planet is not changed.
NOTE: In games featuring the Horwasp Plague, combat of that nature occurs later in the Host Order. For details, refer to the main Horwasp page and those treed beneath it.