"Earth...is all we have left".
The Battle of Earth was one of the largest engagements fought between the Covenant Empire and the United Nations Space Command.
Aftermath of ReachEdit
In the aftermath of the Fall of Reach, the UNSC began to pull its forces back to Earth, with most units assigned to defend Earth's tether cities. The marine unit E2-BAG/1/7, among many others, was relocated from Reach to defend New Mombasa.
Discovery of EarthEdit
The Covenant Empire discovered the location of Earth after the Fall of Reach. The High Prophet of Truth withheld knowledge of this discovery from the Covenant and other High Ranking Officials. To attack the human homeworld, he ordered an assault fleet to secretly assemble at Unyielding Hierophant station in the Tau Ceti System. The fleet would overwhelm Earth's defenses in a single decisive strike.
The Covenant assault fleet was discovered by the UNSC AI Cortana.