Much like the United Nations Space Command, the Covenant Empire maintained a warship categorisation system which determined what position and role their vessels fulfil within their various Ministerial navies.
Made up of the very smallest starships that are recognised as warships, Attack Ships occupy an odd step between strikecraft and true warships, and fulfil the Covenant's need for cheap escorts and cannon fodder in fleet engagements. Weighing up to three million metric tonnes and reach a maximum length of six hundred metres, Attack Ships are the smallest vessels that are classified as warships. They are expected to operate independently or in small groups within the Covenant's borders, and perform menial tasks such as manifest checks, delivering personnel and supplies to ships and naval bases, and respond to civil unrest on their worlds. That said, their wide range of shapes and capabilities makes them a versatile classification. During fleet engagements, their small size restricts the power of their weapons and shields, which means that they must use their speed and strength of numbers to win or offer support to larger starships.
Attack Ships are viewed with disdain by anyone wishing to climb the ranks of the Covenant, and their crews are given a number of additional restrictions. They are forbidden from contacting their Fleetmaster directly, as such an act is seen as wasting their time, and recognition for their battle honours must be verified by at least two other shipmasters. Because of this, and the fact that comparatively few see service in the Covenant's expeditionary fleets, Sangheili treat them as disposable tools. Instead, command of these ships fall to experienced Kig-Yar and Jiralhanae officers, who often tweak and brand these ships with their own markings to make them their own.
In no other class can there be a greater variation. The Compulsors serve three main roles. They act as missionary vessels, bringing the enlightenment of the Covenant to the darkest corners of space, ensuring that a world's tithe is collected promptly, and bringing wrath when either of it's previous roles are obstructed. Compulsor vessels include combat and cargo vessels, ensuring that a world's tithe is collected promptly. Many of their vessels are former carriers, their cavernous holds converted to cargo, but still capable of carrying a complement. Compulsors also include cargo vessels, transportation ships, War-Freighters, missionary ships, and similar vessels.
The Examiner classification is a made up of largely heavy command vessels, equipped to launch and lead large scale campaigns, but the genuine role depends on who commands it. For the Sangheili, the Examiners are flagships, made to lead fleets, launch assaults, and prosecute campaigns, with most being high tonnage ships, with a heavy armament, enhanced communication features, and large complements. The San'Shyuum however, see them as a means of continuing their great journey, using these mighty vessels to search for Forerunner artefacts, or to lead conversion of lesser races into the Covenant faith. Each vessel in this classification meets the criteria to be dubbed a flagship, and has the necessary means of searching for and excavating Forerunner relics.
These vessels can only be activated and used at the Hierarch's will, making Ministries dependent on pleasing and appeasing the Hierarchs in exchange for the most capable of ships.
Ships of the Class: CAS-class assault carrier, CSO-class supercarrier, DOS-class supercruiser, ORS-class heavy cruiser
While most, if not all, Covenant vessels have the ability to war, they have some utility that lies elsewhere, such as in exploration, escort, conversion, or occupation. Executioners, however, are pure warships, with no role or service beyond extinguishing the hated enemy of the Covenant. As dedicated warships, they are heavily, even exotically armed, and capable of savaging enemy ships far larger than themselves. But this ability for wanton destruction is seen as distasteful, as its inability to convert is seen as a hindrance on the Great Journey.
Crewed by exiles and outcasts, the disobedient and disloyal, these vessels are used for where the fighting is bloodiest, and gain few accolades. To serve on these ships is a stain of honour, and these vessels are often relegated to lonely expeditions and patrols, far from the Covenant. Some might say this is a political move: by making the Covenant's most powerful ships a dishonour, the Hierarches were able to exile them from the core, decentralising the potential warships in the event of a Sangheili uprising.
Ships of the Class: ADA-class martyr corvette, CPV-class heavy destroyer, PCS-class fireship, ORA-class Interdictor Cruiser, OSS-class battlecarrier, SCT-class battleship
In the Covenant fleet, there is very little distinction between mobile space stations and smaller starships, so much so that the many ways they regulate their ministries' fleets also apply to their stations - the greatest of which are blessed with the Guardian classification. Dwarfing almost every other starship utilised by the empire, Guardians are the administrative and logistical hearts of their armed forces. They are part-habitat, part-naval base, and part insurmountable fortress. All are mobile enough to conduct interstellar travel, travelling to the hegemony's various worlds to bring temporary prosperity and collect taxed goods. Because they house an onboard civilian populations and can conduct trade, Guardians are classified as mobile civilian colonies and fall outside of the military's authority. As a result, only the Hierarchs can order them to support the operations of their armed forces, where they are positioned as forward naval bases and shipyards.
Ships of the Class: CDA-class battlestation, DVC-class starbase
Unlike most other classifications mentioned, the Procurator classification is not reserved for warships commanded by warriors, but for support ships commanded by San'Shyuum. Procurators are part of a carefully cultivated system of dependency, wherein the logistic needs of the Sangheili, and later Jiralhanae, are dependent on their political ties to the San'Shyuum forcing compliance. Commanded by Minor Prophets, with a high degree of independence, they answer only to the Hierarchs, and for a system governor, Fleet Master, or Ministry to gain their services, they must gain their approval, and work to maintain it. Procurators are not simple supply vessels, but instead serve as mobile logistic depots, manufacturing war materiel, repairing ships, producing food, and providing recreational services.
Ships of the Class: DDR-class bladder ship, DPR-class repair ship, DRA-class utility vessel, DSC-class support ship
Quaestors are workhorse ships-of-the-line, larger than Attack Ships, but rarely exceeds the size of esteemed Examiner-type vessels. They are the single-most numerous 'true' warship classification, with reliable weapons and shields, but lack the efficiency or lethality expected by other Covenant ships of their size. This is because they are designed to be suitable for a wide range of roles, such as scouting, occupation, and unearthing Forerunner structures where needed. Their well-roundedness sees them often becoming flagships for smaller fleets.
Ships of the Class: CAR-class frigate, CCS-class battlecruiser, DDS-class heavy carrier, RCS-class armored cruiser
Many threats assail the Great Journey, from within and without. To this end, the Guardian classification guards the journey through faith and firepower. The Guardian classification are largely escort or reconnaissance vessels, made not to prosecute wars, but to defend from threats. These vessels may range from heavy escorts, protecting dedicated warships, to lighter vessels made to fend off pirates and the like. These ships often vary massively in role and capability, but are unified in their role of defensive vessels.
Ships of the Class: ADP-class escort, DRS-class patrol carrier, RPV-class light destroyer, SDV-class heavy corvette
When the Writ of Union was signed, and the Covenant formed, the Sangheili battle fleets were still exceedingly numerous, with the necessary fire power to usurp the nascent Hierarchs and Council. In an effort to retire these warships, they were marked as Vestiges: weapons of war that were outdated and no longer needed. Some were reused as missionary vessels, extensively refitted for exploration, others were used against the Sangheili as occupation vessels and tithe ships. Others still were mothballed, kept barely active and ready to be reactivated during conflicts. Over the centuries, many were taken to shipbreaking yards to be broken down and recycled. Some vestiges have survived, hidden from the Covenant by Sangheili who refused to bend to their will, and knew that one day they would be needed to throw off the shackles the Covenant imposed on them. Hidden in secret, many of these Vestiges would remain hidden for millennia, until they were needed again. Occasional, these would be found, but were often dismissed as a forgotten ship graveyard, rather than a stockpile.
Ships of the Class: Adomous-pattern Brigantine, Hekar Taa-pattern blockade runner, Sanghelios-class Dreadnaught
In addition to the major classifications in which the Covenant fleet is categorised, each individual type of starship has a role designation system which outlines what tasks they are designed to fulfil. These are divided between their primary, secondary, and tertiary roles, with a corresponding letter used to distinguish them. The only starships that did not receive such a code in the Covenant are Vestiges, as they were designed before the system even existed as a concept. With the exception of some Covenant remnants still inheriting their bureaucracy, this has fallen from use in most Covenant successor-states due to its over-organisation.
There are a few rules that must be taken into consideration. Doubling up on letters signify that a ship is specialised towards that specific designator, and are therefore far more capable than other ships in their respective group. Those that are only as capable as their peers, but are not versatile enough to fulfil another role, may drop a slot, although this comes with a stigma of the ships being cheap and poorly designed in their operator's eyes.
- A - Anointed: This ship is capable of pursuing objectives without the aid of a fleet, carrying the necessary endurance and equipment to do so.
- C - Contrition: This is a multipurpose ship of the line, intended to operate within a standard fleet formation and require support from other vessels within their unit. As a result, they tend to form the bulk of the Covenant's forces.
- D - Divinity: This ship has support functions, such as carrying fighters into battle or disrupting opponents with electronic warfare.
- O - Ordained: This ship is not built to standard, being upgraded with a Forerunner artefact.
- P - Piety: This ship is used for patrol, either escorting larger spacecraft or independently patrolling the spacelanes.
- R - Reverence: This ship is used for reconnaissance, and has the equipment needed to search and unearth Forerunner artefacts.
- S - Salvation: This denotes the ship is a dedicated warship and is suitable for siege operations. They are typically, though not always, armed with at least one energy projector. Uniquely, Salvation-class vessels invert the system, with the most powerful Covenant ships featuring it in their tertiary slot instead.
- Ships of the Class: CAR-class frigate, CAS-class assault carrier. CCS-class battlecruiser, CRS-class frigate, CSO-class supercarrier, DAS-class storm cutter, DRS-class patrol carrier, DOS-class supercruiser, DSC-class support ship, ORS-class heavy cruiser, OSS-class battlecarrier, OTS-class Dreadnought, RCS-class armoured cruiser, SCT-class battleship, SDV-class heavy corvette, SVR-class Siege Cruiser
- T - Tenet: This denotes that the ship class is not intended for mass-production, with there only being a handful of custom-made examples in existence.
- V - Virtue: This denotes a ship that is designed to support ground forces, either directly as aerial artillery or by providing support capabilities.
- X - : This ship is not capable of faster-than-light transit, although it is capable of exoatmospheric travel. X-class vessels always place it in their tertiary slot.