While she was pinned down, a female ISA marine, "Jammer", called out for backup as she and her team were pinned down by enemy forces. When Cpt. Jason Narville couldn't provide more help for Jammer after the Intruders he sent were destroyed, Sgt. Rico Velasquez disobeyed his orders and went of to rescue Jammer's unit. However, Narville and the available Intruders had already made their way toward the cruisers. Narville apologized as the cruisers fled. Rico and the other abandoned ISA forces watched the remaining cruisers attempt to flee only to be destroyed by MAWLR fire. With no one else to turn to, Rico and Jammer gathered whatever remaining vehicles, weapons, and survivors they could find, forming the Raiders.
For six months the Raiders survived and combated the Helghast in guerilla warfare by hacking into Helghast communications and doing hit-and-run missions on several Helghast bases. The Raiders operate intruders fitted with Helghast Heavy weapons, and continue to use their M82 rifles and M224 machines guns in ground combat. They dress in ragged uniforms and wear blankets and scarves over their faces and body to try and fend off the frigid cold of Helghan's colder regions. They generally share their commanders' bravado, and conviction when attacking the Helghast. They hold unmatched camaraderie among themselves and seem to have given up on Jason Narville's leadership. Despite loyally following Rico for 6 months, several Raiders express reservations on saving Narville. Jammer seems to act as the second-in-command of the Raiders, since Rico allowed her to take command while he and Sev go off to rescue Narville.