From Halopedia, the Halo wiki
Unified Earth Government
Trône was an expansive metropolis on Meridian, a human Outer Colony of the Unified Earth Government.
In 2549, Trône was invaded by the Covenant as the Battle of Meridian began. As the United Nations Space Command defended the city, a jetpack-equipped Spartan-III assisted in repelling Covenant forces occupying Trône. Meridian would later fall to the Covenant in early 2551 and the world's surface glassed from orbit, destroying most of Meridian's cities and infrastructure.