Glassing

"You are...all of you...vermin. Cowering in the dirt thinking... what, I wonder? That you might escape the coming fire? No. Your world will burn until its surface is but glass!"

- Prophet of Truth



The term Glassing, also known as Plasma Bombardment, is used to refer to the act by which a Covenant ship or ships bombard a planet from orbit using their plasma weaponry.

Doctrine
Glassing, a destructive process which signifies an end to a planetary body, begins with the discovery of an enemy controlled world. The Covenant have been known to immediately begin glassing a planet, but in most engagements, the Covenant first deploy ground forces for various reasons (usually to search for and/or secure Forerunner artifacts). A Minor Prophet is assigned to most Covenant fleets to oversee the destruction of a human world. Before the fleet is permitted to destroy a planet, the Prophet performs a religious ritual - this process lasts an hour, and when completed, the Prophet declares by which religious significance, marked by a glyph, will the world be destroyed. There is currently only one known instance of a human world having a glyph burned into its surface. The Covenant will then begin glassing the planet by moving their large warships close and blanket the world with a series of crisscrossing orbits to ensure that every square millimeter of the surface is destroyed. Throughout the war, the Covenant have been known to utilize two methods of glassing.

Orbital Bombardment
The first and the most commonly used method is when the Covenant's large warships aim their plasma turrets towards the planet's surface and build up plasma along their lateral lines. The plasma is then discharged in lances from the warship as it continues to orbit the planet - contained within a magnetic bubble, the lances are guided towards the surface by the ships automation, striking an area and converting the top soil and other surface geology into a mineral called lechatelierite that is similar to glass, hence its name. The process also vaporizes any bodies of water the planet may possess, or at least reduces the remaining water to pools choked with ash. The ecosystem of a planet is also disposed of through this process. This is repeated until every square centimeter of the planet is destroyed; depending on the planet, the technology and the number of ships in the Covenant fleet, it can take the Covenant a minimum of some hours, or up to two days to glass a planet. The impact of the plasma bolt is similar to that of a nuclear detonation on a much different scale. When the plasma bolt impacts the surface, the magnetic field sustaining and guiding the plasma collapses, and, depending on how powerful the release of energy is, the initial zone of impact is obliterated instantly. The areas outside of the initial impact zone are affected by the heat wave generated by the blast; depending on the range, those closest outside of the blast zone are instantly killed by the intense heat. As thermal expansion takes over, the resulting flames fan out and create a pyroclastic surge, which will continue to burn the areas it comes into contact with until it has cooled enough that it cannot harm the surface.

Subsequently, the atmosphere is covered with soot and ash thrown up from the initial impact, subjecting the planet to a nuclear winter. As the initial impact area cools, the surface is covered by extensive areas of molten soil, and is comparable to active volcanic sites in some parts of the world, on a larger scale depending on the extent. The destructive process leaves the planet unable to recover to its former state. As a result of the destruction, the atmosphere of most planets have been known to boil away from the process, though not all planets suffered this, with the most notable exception being Reach, as it was only partially glassed.

Low Range Bombardment
The second method is used when a ship must effectively destroy a ground target from low range. This method involves focusing plasma though a magnetic envelope from the Energy Projectors located on the underside of the ship, most notably the area where a ships grav-lift is located, and then discharged as a narrow beam; this method of low-range glassing has only been witnessed a few times, most notably during the Battle of Pegasi Delta and the glassings of New Mombasa and Voi during the Battle of Earth. This method and use is not to be confused with the Covenant Excavation Beam, a type of weapon on Covenant Cruisers and Carriers used to excavate areas of interest to the Covenant. This powerful beam serves a dual purpose: While primarily used to excavate an area using plasma to "burn" through an area, it is also used as a tool to destroy large structures. If any living thing is in the path of the beam, it is disintegrated instantly.

History
Since the formation of the Covenant in 852 B.C., the Covenant have used their ship-borne plasma weapons to threaten the lesser species of the Covenant into a truce and their eventual induction into the Covenant. The Lekgolo were the first to be threatened which such destruction because of their transgressions against Forerunner technology before becoming the first outside species to join the Covenant in 784 B.C. The Unggoy almost faced orbital bombardment for their Rebellion in 2462, or the 39th Age of Conflict by Covenant records. Although the Kig-Yar were not threatened with orbital bombardment, they were quick to realize the Covenant had such a capacity to destroy them and thus chose to join the Covenant for greater wealth that the Covenant would provide.

Human-Covenant War
After the discovery of the humans and the Prophets' call for humanity's destruction, the Covenant would put all of their destructive methods to use, and throughout the Human-Covenant War, the Covenant aggressors glassed a significant majority of the UNSC's colony worlds from orbit. Although ground forces were often deployed first, as UNSC forces were routed in space, the bombardment would commence. The first planet to suffer this fate was Harvest, partially glassed from the Jiralhanae-operated cruiser Rapid Conversion.

The destruction of a human-controlled world varies upon many different factors, from the world itself and its defenses, to the requirements of the Covenant fleet and its leader be it a Fleet Master or Prophet. Undeveloped human colonies - ones that are atmospheric, contained habitats or stations - are typically destroyed while the rest of the world is left unharmed; however, planets that have been terraformed may be destroyed by many different methods.

It has been noted that areas of interest to the Covenant are left intact for reasons of study or retrieval; however, this is not common, as only three planets have been partially glassed and only when a Forerunner Artifact was discovered. After the Covenant glasses a planet, a shard of glass is removed and placed in the Sanctum of the Hierarchs within High Charity, where it hangs with countless other shards from worlds glassed by the Covenant.

The Battle of Earth culminated in the glassing of the city of Voi in Africa by Covenant Separatists, in an effort to contain a Flood infestation which had come to Earth only hours earlier. Lord Hood accuses the Sangheili lead fleet of glassing half of the continent, but given his distaste for his former enemies, he might have exaggerated about the actual extent of the glassing.

Halo Wars
In Halo Wars, the Prophet of Regret faction of the Covenant are able to use the Prophet to call down a Cleansing Beam from an orbiting Covenant ship. Rather than a leader power, this is treated as the unit's secondary ability, using the Y button to guide the beam at the cost of resources every second. Much like Captain Cutter's ability to fire a MAC blast at enemy targets, this attack lacks the power of typical glassing maneuvers seen in past canon to balance gameplay. However, the power may also have been lowered to avoid Covenant casualties.

Trivia

 * By the end of Halo: First Strike and Halo 2, it is believed that the Covenant had glassed 76 planets which were represented by 19 shards in 4 rows in the Sanctum of the Hierarchs.
 * It has been noted that UNSC territory encompassed over 800 planets at the beginning of the Human-Covenant War, most of which were glassed by the Covenant.