They disappeared in 2541 during a training exercise near Zone 67 on Onyx after having reported sightings of a "floating eye." It was discovered years later by Kurt-051, Catherine Halsey, Franklin Mendez, along with the surviving Spartan-IIs and IIIs, that they had encountered the Onyx Sentinels. They were probably killed by the Onyx Sentinels that they encountered, due to never having faced this opponent before.