SUMMARY
The Battle of New Jerusalem was a Covenant attack on the colony of New Jerusalem in the Cygnus system sometime in July or August 2552. While the UNSC Army and Marines put up a strong resistance to the Covenant attack, the planet was eventually overrun and glassed.
RELATED MEDIA
These events are referenced in the short story Dirt, from the anthology Halo: Evolutions, and the video game Halo 3: ODST.