Rear Guards are the third most common regular mercenary behind the Scout and Cover on most levels of the game. They will often work with Cover and Scout soldiers. Unlike their counterparts they do not wear protective jackets but wear a waistcoat over a shirt with ammo pouches. Oddly enough, they also carry what appears to be a strip of shotgun shells but are usually armed with M4s. Uncommonly, rear guards also sometime carry a Desert Eagle and, on the level Swamp, the M249. In a typical firefight, Rear Guards will fire their primary weapon and try to throw grenades at you from the rear of the group whilst Cover soldiers attempt to pin you down. Rear Guards will especially throw grenades if you are hiding behind cover, therefore taking them out first is advisable.
-At the very start of the level steam, if the player walks deeper in the Island and kills the 3 trigens in the area, the corpse of a rear guard with a silenced MP5 next to him can be seen. This is the only time in the entire game that a rear guard is presumed to have used a silenced MP5 as any other rear guard seen in the game, dead or alive are never seen using or having that weapon next to their corpse.
-Aside from Crowe, the Rear guard is the only other enemy to wield the M249, and even then, this is only seen on the level Swamp, rarely.