 In 2552 , the Covenant arrive at the UNSC 's last major stronghold beyond Earth – the planet Reach , in orbit of Epsilon Eridani – and launch an invasion of the planet . The last Spartans and UNSC military are unable to stop the Covenant from bombarding the planet . The UNSC Navy suffers devastating losses , and every Spartan but their leader , player character Master Chief John @-@ 117 , is believed lost in action . Following directives to avoid leading the Covenant to Earth , Cortana , the AI aboard the fleeing UNSC ship Pillar of Autumn , selects random coordinates that lead the ship to a Halo installation . These events form the backdrop to the first game in the series , Halo : Combat Evolved . 
