"Do not misuse my generosity, Shipmaster. An assault carrier is a tool of destruction, capable of beating even fleets of ships unaided. If you abuse it or my trust for anything beyond the mission I have gifted you, you will not only bring shame upon your house and your entire homeworld, but I will personally hang your skull above the door to its command centre as a lesson to all who disobey me."
The CAS-class assault carrier is one of the most powerful models of capital ship ever deployed by the Covenant empire. Characterised by its immense center hangar and hook-like prow, the assault carrier's awe-inspiring capabilities are well-documented. It is designed to lead the Covenant fleet into known enemy strongholds, punching through enemy lines and offloading a large complement of ground troops to wage war on the planet's surface. They accomplish this with line-after-line of shield generators, plasma torpedo silos and pulse lasers, with an expansive hangar capable of carrying thousands of strikecraft, dropships and troops. Add to this a number of powerful plasma lances and stripping out the usual warship needs for more weapon, troop and reactor space, and it becomes unnervingly easy to see why these ships are often called invincible combatants by personnel on the front lines.
The CAS-class assault carrier was first deployed against humanity during the Massacre of Bliss. Contrary to popular belief, the five assault carriers here were only supported by a massive fleet consisting of dozens of RPV-class light destroyers, CPV-class heavy destroyers and CRS-class frigates. They overwhelmed the planet's meagre defence fleet and proceeded to instantly glass the defenceless colony. Within four hours, all five hundred million colonists were burned to ash and glass; this was the first in a cycle of losses that would contribute to the CAS becoming among the most feared ships in the Covenant fleet.
Fortunately for humanity, the UNSC would gain a much-needed morale boost when they proved the assault carrier could be beaten. In 2526, Vice Admiral Preston Cole would lure the Covenant fleet from Bliss into a trap within the Origami Asteroid Field during the Battle of Alpha Aurigae. He maneouvered four particularly-large asteroids, each measuring at least six kilometres in length, with weapons fire to direct them towards the Covenant fleet. His ships followed closely behind, and when they were in effective range they sprung out, firing on the two closest carriers, destroying one and crippling the other. While none of the asteroids hit their intended targets, it left the Covenant in sufficient confusion to allow Cole's fleet to speed past the Covenant, before turning around and unleashing a MAC barrage, destroying the other two carriers. In the end, Cole lost thirty-seven ships to this risky tactic, but the fact he destroyed three of the largest ships encountered to date did reinstall the public's faith in the UNSC's ability to win the war.
Despite isolated cases where these ships were destroyed, CAS's use as flagships saw them becoming signals of the Covenant's inevitable victory. Throughout the early war, entire armadas of even modern UNSC ships were destroyed by being charged by a single assault carrier. The fact that they often carried skilled military commanders, like Imperial Admiral Xytan 'Jar Wattinree, and were escorted by particularly-massive fleets only made it worse for those tasked with fighting them.
Utilised almost exclusively by the First Fleet of Gallant Ingenuity, the Eiolkaar-pattern assault carrier is the successor of the fleet's previous Esgem-, Kerel-, and Mendural-patterns in an effort to standardise all heavy capital ships within the Covenant remnant. Built on the frame of outdated and decommissioned warships such as the fleet's CCS-class patterns, these ships have been outfitted with enhanced subsystems and fallback systems to protect against electromagnetic pulses. The UNSC first became aware of the existence of this pattern while research was conducted on Installation 07, where one vessel with several escorting CCS-class battlecruisers and Type-57 Phantoms passed it over during what is believed to be a patrol of the sector. It is believed that this fleet is aware of the Halo's significance but does not seem to react to its presence. Like all First Fleet ships they are often a darker purple colour, but in the case of CAS-class carriers, the Eiolkaar is identical in colouration to Kerel-pattern carriers, with the white lights of First fleet refits.
Easily the most common pattern of assault carrier encountered throughout the war, the Esgem-pattern assault carrier is as close to a standard as one could get within the Covenant. Equipped with a 'mere' forty-metre hull of nanolaminate, the Esgem-pattern also features the lightest shielding and weapons output among the class, and a fleet coordination suite useful for only commanding battle groups smaller than a dozen ships. As a result, when given the option many fleet masters request reassignment onto a different pattern when available.
Fortunately for the Esgem, it is not completely useless. It is still a formidable warship, capable of easily beating fleets of even smaller Covenant vessels with ease, and provides a number of incredible opportunities for shipmasters to exploit in combat. The first is its speed; the Esgem is actually far lighter than other patterns of assault carrier, and this allows it to pull off manoeuvres that would be impossible in another subclass of carrier. This made it extremely-effective at assaults, where it can effortlessly punch through the defensive net and begin landing ground troops. This led to the carrier's next advantage. Because it did not have as many weapons, the Esgem could carry about twenty percent more soldiers and material, allowing it to either instantly deploy more troops at once or sustain them for longer periods of time. Another advantage lies in its adaptability; the Esgem's reactor is just as powerful as any other subclass yet the demands on it have been greatly reduced. This ensures that power can be redistributed to other systems in combat, usually weapons, or support additional external upgrades to its hull. In fact, the age of an Esgem can sometimes be told on based on how extensively its internal systems are upgraded. Finally, as its ultimate trump card, the Esgem usually supports a Hiranum-pattern slipspace stabilisation beacon. This tool allows for a tactical advantage by manipulating the local space-time fabric to allow its fleet to traverse the dimension at higher speeds, or more usually to call in reinforcements to jump into its immediate vicinity. It has been seen that the beacon can defeat slipspace inhibitors, allowing for travel in places where it should not be able to jump in theory.
"A well-disciplined crew are more valuable than even the most powerful Kerel."
―An old Sangheili proverb.
A mutation of the base Syfon-pattern, the smooth Kerel-pattern assault carrier is among the strongest warships in the Covenant fleet, and feature the closest imitations to the Forerunner technology ever created by Huragok craftsmen. In fact, the Kerel is so valuable that only shipyards blessed by the Hierarchs themselves are allowed to construct these, and only Sangheili given special permissions by the High Council are permitted to crew them, with a special ceremony being held transferring these ships under the command of a new shipmaster. In fact, it is possible for centuries to go by before these valuable warships are crewed.
The Kerel-pattern assault carriers have an unimaginable level of firepower. Built more like a battleship than any class of carrier, the Kerel is capable of unleashing thirty percent more firepower than any other pattern of assault carrier, which includes up to a dozen energy projectors. Its shields are among the strongest in the Covenant fleet, only beaten out by the raw power supplied by the CSO-class supercarrier. Even its engines are upgraded to the Raphyus-pattern to push the massive beast, making these ships as shockingly fast as an Esgem-pattern, although arguably less manoeuvrable in combat. While their troop capacity is reduced, it can still carry enough soldiers to lay waste to even the heaviest-fortified worlds and attack entire fleets. As a result, the Kerel is a ship master's dream vessel to command, making the contests to command them all the more vicious and invigorating.
Unique in that it was secretly fabricated by the Jiralhanae on the Prophet of Truth's orders, the Medural-pattern assault carrier, despite being a Sangheili-named craft, is a less-elegant and more raw variation of the CAS-class assault carrier. More thickly-armoured due to raw construction methods, the Medural relies on cruder, more reliable and easier to maintain technology to function. As a result of its unnecessary over-massing and raw architecture, these carriers are favoured by Jiralhanae shipmasters and are generally avoided by Sangheili for fear of being judged by their own kind.
The first major deviation from other assault carriers is its well-greebled hull, which seats some additional light plasma cannons and external components. The hull can be up to fifty metres thick in places and is made of an ablative blend of Nanolaminate, a strange form of ceramic and metal, making it stronger, lighter and more flexible. This is further supported by electromagnetic plates, which give off variable light seen on the carrier. The internal corridors are very feudal in their look, with much more angular panelling, with sword-like locks on doors. Even the colours tend to be muted down to shades of grey, though during the Great Schism they were coloured purple to reflect their new position. This was all more comfortable to the Jiralhanae, who preferred the rugged, industrial style.
Unlike any other pattern of assault carrier, the Syfon-pattern is designed first as a civilian vessel, being a luxurious cruiseliner for the Covenant's political elite. Built above and below its beautifully-crafted silver hull is an entire city containing thousands of individuals, and entire clans of Sangheili can forever be raised on the back of these ships. As a result, the Syfon is seen as the crowning jewel of a San'Shyuum's career, and as most of these carriers are privately-owned, being assigned to one represents that an individual has shown a great amount of loyalty to the San'Shyuum that owns it.
However, as it was also designed by a Sangheili shipwright, the Syfon does have its military applications. As it contains a larger reactor and large hunting paddocks to sustain the indulges of its inhabitants, these assault carriers can only carry forty percent of the ground assets a regular carrier can, so it is forced to make it up in other areas. The Fib-pattern shield generators are three times as strong as the shields on other assault carriers. However, with large agricultural spheres and an internal fabricator capable of creating the latest fads in technology, the Syfon is designed for long-distance military deployments and sees extensive use as a heavy explorer. When a new relic is discovered in unknown space, the Syfon is usually at the forefront of the fleet sent to secure it.
The Syfon-pattern carrier has only been infrequently-seen during the Human-Covenant War, as Sangheili commanders preferred to serve on more purpose-built warships. However, these ships have been seen as flagships, with politically-savvy Fleet Masters carrying promising families and their home clans in an attempt to climb the societal ladder.
Occupying a strange position between a prototype and the first true production model of the CAS-class, the Wixsom-pattern is a block of at least one hundred vessels manufactured almost a millennia before the twenty-sixth century. Very few of these powerful warships have survived the ages, and those that do are used in merchant guilds to ply their trade. All are diverse in their systems layout, a common sign of the overlaying retrofits used to keep them in service.
Maintaining an appearance like Kerel-pattern assault carriers but with a more bulbous and stylised midsection and aft, and upward-swept hooks on each side of the hangar, examination of a single abandoned Wixsom-pattern assault carrier reveals some interesting insights. They were very well-protected for their time, with a well-reinforced hull structure that uses outdated strengthening techniques and very advanced shields. The shields, defying historian's expectations in both defensive capabilities and their refresh rate, are extremely power-hungry and require constant maintenance. Tests have shown that the reactor is unable to supply enough energy to them when all the other systems are operating; most Sangheili shipwrights familiar with the artifact believe that a second, dedicated reactor may have been installed at one point but was removed for reasons unknown. Its weapons are far less impressive, being both few in number and horribly outdated. Most were variations of photonic beam-lasers, which are bulky, inefficient, and cause far less destruction than even plasma weapons at the time, although there appeared to be docks for self-propelled weapons and disruptor technology. Its cargo-space is higher-than-average when compared to contemporary CAS-class assault carriers, although the density of crew living space cast doubt on it being able to carry more living troops. It is unknown as to how fast it is, as no known surviving Wixsom-pattern has the original engines - the sole vessel most of this information is gleamed from suffered extensively from micrometeorite impact in this area.
It is unknown what the Wixsom's intended role is, with few agreeing on this area thanks to a lack of information in surviving Covenant records. Due to the ship's logs stating that it ferried a "[Supreme] Commander of Rejuvenating Spirits", and its odd defensive focus, it is debated that it was designed as a shuttlecraft for VIPs. Others point to it being a tank vessel, arguing that its weapons are used only to keep fire focused on it. A fringe set of human researchers are adamant it is a command carrier, commanding the fleet and staying back to provide force projection - the Covenant doctrine for the time, no evidence of a sector-grade command centre, and its unconfirmed troop complement cast doubt on this theory, however. Currently, Wixsom-pattern assault carriers are used as freighters or transports. Those once again pressed into military service are being forcibly upgraded to approach even acceptable standards for an assault carrier, and are forced to serve within similar roles.
Developed and deployed exclusively by the Demiurge, the Wrath-pattern has removed several ship-to-ship batteries, and instead replaced them with longer ranged, heavier plasma cannons. While they have a reduced rate of fire, their accuracy and range are increased, making them deadly at ship-to-ship combat, or at orbital bombardment.