The Battle for Nenia Pomarium - or more accurately the battle to hold Port 624, was a battle fought in late M41. The Space Marines of the Revenants Chapter's Fourth Company - were sent to the planet Nenia Pomarium to investigate the possibility of a Genestealer infiltration. By the time they get there, the Tyranid force known only as the Alpanga Swarm had already arrived, necessitating a last ditch holding action to pull the untainted survivors out.