Factions that attack the 5th Marine Expeditionary Unit are found here.
“The Brute Bloodpack is one of the main factions that the player can join. The faction is unique...Brute Bloodpack
“The Covenant Remnants are one of the main hostile factions players will encounter when playing...Covenant Remnants
“HOTH is an enemy faction that is unplayable for the player. The player will be facing them...Hands of The Harbringer