DM-3-1123 b
From Halopedia, the Halo wiki
DM-3-1123 b[1] was a planet in the DM-3-1123 System.
It had a population of approximately 1.3 billion Forerunner beings.
A Forerunner naval group engaged a Flood irregular naval group of 149 non-military vessels over DM-3-1123 b, destroying their vessels, but their sole intention was to infest the planet, and within 32 hours, they had overrun local Forerunner ground forces, and 0.0006% of the planetary population was evacuated before the Forerunner local fleet, upon an 83% concensus, launched a "blanket orbital bombardment" of DM-3-1123 b, destroying the Flood infestation but rendering the planet inhabitable and sacrificing much of the original population.