 By the events of Halo 3 ( 2007 ) , the Flood intelligence known as the Gravemind infests and captures High Charity , while the Elites assist humans on Earth in defending themselves . Truth 's forces excavate a portal to the Ark , located outside the Milky Way . The Elites follow Truth , and the Covenant Arbiter , or holy warrior , kills Truth . After High Charity arrives at the Ark , the Arbiter and Master Chief decide to activate a partially built Halo ring ( the replacement for the ring that the Master Chief destroyed in the first game ) destroying the Flood and sparing the rest of the galaxy . The remaining humans and Elites escape back through the portal . The Human @-@ Covenant war ends in March 2553 , and the Arbiter leads his Elites back to their homeworld . 
