Jul 'Mdama's Covenant forces follow the Didact to Installation 03, where they try to recover a Forerunner device known as the Conduit. A Spartan-III headhunter is sent to stop them, but 'Mdama's forces successfully escape with the Conduit and head to Earth through a portal. They use the portal to send Covenant fores and Prometheans directly to New Phoenix, where the UNSC is forced to try and fend off an invasion. After a brief battle, the Spartan-III successfully recovers the Conduit and uses it to shutdown the portal to Earth, ending the invasion.
Roland walks you through the events of the Battle of Installation 03 and Battle of New Phoenix.