Battlecruiser

A battlecruiser is a designation of capital ship used by human-led factions, such as the UNSC Navy. They have the hull classification symbol of CB. As the 'middle child' of heavy spatial combat ships, battlecruisers are envisioned to combine the raw fighting potential of battleships with the mobility of cruisers.

Characteristics
Battlecruisers are an anomaly in the human classification system. While most ships in this category have maximum mass of 25 million metric tons and a length that exceeds two kilometres, this is not a hard rule that is enforced. Instead, they are defined as any capital ship that is primarily designed for ship-to-ship combat in space, more heavily armed than a heavy cruiser, and can maintain pace with fast-moving fleet squadrons. Traditionally, this results in a larger hull that is armed with large battleship-grade weaponry but only has enough armour to protect it against cruisers. However, there have been exceptions: some have inverted the scheme and rely on extremely good protection and sport munitions used on their smaller brethren. The only commonality all battlecruisers have lies in their high acceleration and endurance.

The primary consideration for the use of battlecruisers revolves around their ability to force battles where it holds a decisive advantage, avoid those that favour the opponent, and to exploit holes in enemy defences by making deep incursions into their territory. As a result, the bread-and-butter of battlecruiser missions sees them leading attacks on poorly-held bases and positions, intercepting raiders, and running down the stragglers of defeated fleet engagements. In combat, they excel at hunting down and crushing weaker forms of capital ships, which can include attack carriers, cruisers, and even other battlecruisers. They maintain a degree of versatility from their cruiser roots, with many emphasizing command, fast carrier escort, and even scouting to various degree. In peacetime, they are excellent symbols of status and diplomatic pressure, routinely carrying dignitaries and making port visits to reaffirm the influence and prestige of their polity.

Large cruisers
Large cruisers, also known as "super-heavy cruisers" by the media, is the name given to battlecruisers built to a specific design theory. Rather than arming themselves with individually more powerful weapons, they follow the principles used to design smaller cruisers. They generally have a somewhat more versatile construction, with larger numbers of smaller, lighter armaments paired with intermediate batteries, and using the saved weight to upgrade their armour. Because of this, they can fulfil the same niches their smaller cousins can, with their enhanced capabilities often putting them in command of cruiser squadrons.

Large cruisers were created during the Pax Humana as a compromise with politicians in the UEG Senate, who were often reluctant to fund the construction of battleships and battlecruisers in peacetime. Their heavy weapons were seen as unnecessary and inadequate against anything other than capital ships. As a result, large cruisers were often the strongest ships the UNSC could devote to combat operations, supplementing carriers in the role of force projection. Prior to the Insurrection, dozens of ships in this class were commissioned by the UNSC Navy as a contingency measure against potential rogue CMA capital ships, a threat that would diminish as the rebellion escalated. During the war against the Covenant, they were slowly phased out and replaced by battlecruisers, as the light weapons often mean that they have to fight Covenant warships at dangerously-close ranges.

Large command cruisers
Large command cruisers (hull code: CBC) differ from their close relatives in that they have a large flag deck that accommodates the facilities needed for the ranking admiral and his staff. Often seen leading Numbered Fleets, these vessels are rarely built as original designs, and are normally modified from existing lines of battlecruisers and large cruisers at the time.