DM-3-1123

DM-3-1123 was a habitable planetary system with a population of 226,911,000,000. The Forerunners populated the world of DM-3-1123 b in DM-3-1123, but it was eventually attacked by the Flood. While a Forerunner naval group engaged a Flood fleet of 149 non-military vessels in the system, the Flood landed on DM-3-1123 b and infested it, and the Forerunner fleet was forced to bombard the planet to cauterize the Flood's spread. About 1.5 million of the 226,911,000,000 residents were evacuated from the planet.

Trivia

 * The system's name is possibly another 7 reference: 1+1+2+3=7