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Meridian Bay is located on Mars. It is the site of major Cabal activity, as well as the ruins of Freehold and the former gateway to the Black Garden. Many Cabal Legions are based here, embroiled in a war of attrition with the Virgo Prohibition. The Cabal are mostly fighting the Vex on Mars streaming out to protect the black garden, and have created an exclusion zone with heavy defenses to keep the Vex back, although Guardians have no trouble slipping through their defenses to get to objectives.
The Cabal Legions don't often work together, so Meridian Bay is divided between assigned sections. The Sand Eaters control most of the region, and consequently, suffer the most losses from Guardian, Vex, and Taken assaults.
During the events of the Red War, the Red Legion invaded the Meridian Bay, taking the Bastion and destroying the gateway to the Garden. It is assumed that the Red Legion lost the bay after the death of Dominus Ghaul, as survivors from the War had retreated to the Hellas Basin in a desperate last stand.
During the events of Season of the Risen, Empress Caiatl and her Psions intercept a Psionic Broadcast in Meridian Bay that persuades others with Psionic Abilities to defect from the Cabal Empire and join their Psion conclave. The Guardian would be sent to deal with the broadcasts and eventually shuts them down.
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