CE-10-2165-d
From Halopedia, the Halo wiki
CE-10-2165-d was a Forerunner-occupied planet around 100,000 BC.
12,423 small recreational vessels and seven freighters appeared within the planets orbital perimeter. The Flood used the smaller ships as an ablative armor, taking all damage and protecting the Freighters, which descended to the planets surface and unloaded its passengers over large population centers.
Although the local Forerunner orbital forces were prepared for an invasion by the Flood, they were unable to prevent the infection of the planet and was overrun in a manner of days. Rather than allow the Flood to consume the planets civilian population, the Forerunner Navy destroyed its own cities from orbit denying them to the parasite for use as biomass.
Mendicant Bias passed the planet, watching the events unfold, as it traveled to engage the Compound Intelligence.[1]