Season 13 is set on the once owned UNSC planet, Chorus, shortly after the Reds and Blues help end the Chorus Civil War between the Federal Army of Chorus (FAC) and the New Republic (NR), by exposing the involvement of Locus, Felix and their fellow mercenaries led by former UNSC Oversight Subcommittee Chairman Malcolm Hargrove. It is now all-out war with the Blood Gulch Crew and Chorus fighting against Hargrove and his space pirates.