Official rule text
78.10 After a combat ends, the player with one or more ships remaining in the system is the winner of the combat; the other player is the loser of the combat. If neither player has a ship remaining, the combat ends in a draw and there is no winner. a If the winner of the combat has fighters or ground forces in the space area of the active system and those units exceed the capacity of that player’s ships in that system, that player must choose and remove any excess units. RELATED TOPICS: Capacity, Fleet Pool, Opponent, Sustain
View official source
Source: Living Rules Reference and FAQ - Prophecy of Kings
Expansion: Prophecy of Kings
Version: 2.0
Reference: Rule 78.10