While these units had very little contact with one another, they all took up the banner of the Eridanus Colonial Resistance, a modification of the name of the Eridanus Colonials, some of the first Insurrectionists that fought the UNSC during the planet's colonization. Despite the heavy UNSC presence, the groups that made up the ECR performed a number of attacks, raiding detainment centers holding captured Insurrectionists, assassinating Office of Naval Intelligence and United Nations Space Command, and sowing general chaos.