From Halopedia, the Halo wiki
Etalan, known to the Covenant as E'gini, was a planet of the Igdras system and an underdeveloped human Outer Colony of the Unified Earth Government, located in the Polona sector. Etalan was once home to ten million humans who lived a nomadic lifestyle, inhabiting a hundred thousand small settlements, such as camps, villages, and pastures. The people of Etalan were poor and primitive, as well as thinly populated. The planet was only host to a single spaceport.
Etalan was a planet dotted with green pastures. On the equator, there was a massive shield volcano that could be observed venting ash and steam from orbit. After the Fleet of Inexorable Obedience glassed the planet and destroyed the shield volcano, an eruption was triggered that suffocated Etalan in ash, with slate-gray bands of ground showing between pearl-colored ribbons of smoke and ash. The volcano became a massive orange lake of lava, flooding Etalan's atmosphere with smoke.
Rise of humanity
On or before March 8, 2526, Etalan was attacked by the Fleet of Inexorable Obedience, the Covenant's primary invasion fleet commanded by Fleetmaster Nizat 'Kvarosee. Ten days later, the Covenant fleet was still in the process of glassing the planet, having destroyed nearly half of Etalan's settlements and the colony's only spaceport. However, the Minor Minister of Artifact Survey grew impatient with the lengthy glassing process. To ensure the deaths of Etalan's inhabitants without spending another cycle glassing the planet, 'Kvarosee bombarded Etalan's shield volcano with plasma fire, triggering an eruption that filled the sky with ash. With the destruction of Etalan's biosphere ensured, the Fleet of Inexorable Obedience moved on to Biko in the nearby Kolaqoa system, though the fleet left its logistical elements at Etalan until victory at Biko was assured.
With the Battle of Biko ongoing, the Point Blank-class stealth cruiser UNSC Vanishing Point and two prowlers traveled to the Igdras system to attack the Fleet of Inexorable Obedience logistics vessels, hoping to stall the fleet's advance into human space. Upon arriving over Etalan, the stealth ships deployed Spartan-IIs to infiltrate the Covenant ships and destroy them from within using HAVOK tactical nuclear weapons. The Spartans ultimately succeeded, destroying most of the logistical ships, aside from the agricultural ships and a handful of medical vessels. 'Kvarosee called for a new logistics flotilla to collect the surviving vessels at Etalan and rendezvous with his fleet at Biko. After witnessing the flotilla's arrival five days later, Doctor Catherine Halsey deduced the location of the Covenant colony of Zhoist, based on its distance from Etalan.
List of appearances