Leviathan-class assault carrier

Considered the harbinger of modern battlecarrier design, the Leviathan-class assault carriers were a series of unusually heavily-armed planetary assault ships commissioned by the CMA Navy in the wake of the Inner Colony Wars. Although they served prestigious careers throughout the Pax Humana, by the time of the UNSC-CMA Cold War they were considered slow, outdated, and too poorly protected for modern fleet service. In light of this, many would be sold or transferred into service of colonial defence forces, often as part of arrangements that aligned governments with the CMA's political doctrine.

Development
The Leviathan-class were conceptualised and laid down as large slipspace-capable cruisers or "Interstellar Cruisers", whose origins could be traced all the way back to the CMA's failed "Galactic Capability" procurement bid of the 2350s.

Chosen as the winning bid out of four separate entries, the proposed cruiser configuration called for a high-endurance large cruiser. Measuring almost 1,300 metres long and massing in at over eight million metric tons, it was only somewhat more powerful than existing cruiser designs, with the extra missiles being used to extend operations. Instead, most of its tonnage went towards electronics and space for sensors, command-and-control, and cyber capabilities. Its AI core, for instance, dwarfed all those built before it, and its flag deck had been based around configurations used for the UNSC's proposals for their new FLEETCOM Headquarters on Earth. Surveillance satellites, new defensive countermeasures, and a squadron of seven fighters rounded out its capabilities.

The first three cruisers were approved and laid down in PassiGear Manufacturing Company's drydocks above Earth and the Jovian Moons in 2389. The escalation of the Inner Colony Wars led to the oxymoron that despite more ships being ordered, redesigns to incorporate wartime experience and delays with allocating enough drydock workers meant that even by 2395, none were close to completion.

Converted Purpose
The first proposals calling for the conversion of the Leviathan-class hulls into planetary assault ships first appeared in 2394, amid the expulsion of the CMA garrison from Falkirk. Subsequent attempts to pacify the colony saw the CMA task forces being humiliated, with the Army Expeditionary proving far too small to invade the planet on a large scale. In addition, the rebels acquisition of CMA naval weapon stockpiles meant that conducting close naval support was fraught with considerable risk, with issues redirecting enough escorts into the theatre to give them subsequent protection.

It was here that the CMA admiralty began looking at the paused hulls of the Leviathan-class. Analysts estimated that modifying the hulls would allow them to be completed in half the time of a purpose-built carrier, and would give them a much faster and more heavily-armed ship to boot. That these reports only calculated the best-case construction scenario did not seem to be taken into account. As a result, PassiGear and their subcontractors, which now included SinoViet Heavy Machinery and Halifax Space were, were given approval to begin the conversion. It was also that this point that Brigadier-General Holger Skjeggestad, war-hero and veteran officer of the Army Expeditionary forces, became aware of the project and pushed for the incorporation of multiple novel features he felt were necessary for his troops.

Despite the changes being implemented in 2396, the first ship to be completed, CMA Colossus, was commissioned in 2401, almost a year to the day since the UEG implement their reforms that ultimately ended the Inner Colony Wars. Although the idea was raised to scrap the ships or even reconvert them back into cruisers, the CMA ultimately succeeded in arguing to complete all 22 ships in their modified state.

Specifications
In the context of the early 25th century, the Leviathan-class assault carriers were very large and very capable military assets that were fully tailored to the needs of early interstellar operations.

In line with their cruiser roots, the Leviathan-class carried enough firepower to single-handedly escort themselves and provide close naval support for a moderate insurgency. Most of this was oriented towards fighting across extended distances, and for this reason was almost completely made up of guided missiles. These were divided between 97 Class-I cells, which were further subdivided between "long" and "short" pods. The former took up roughly twice as much depth, which allowed for them to carry extended-range area-defence missiles or double the number of devices used solely for protecting the mothership. The twenty Class-II cells were normally relegated to surface-attack and medium anti-shipping missiles; given the fact that no ship could be armored heavily enough to stop a single device, this was more than adequate. A keel-mounted bay carrying eight nuclear-armed Shepherd-class cruise missiles, capable of engaging fortified targets across a planetary system, gave it enhanced stopping power over any foe a cruiser could not defeat. Finally, six twin M660F Castle 20mm/50 cal point defence guns were carried. Although carried in order to provide a "last ditch" defence of the mothership, in a pinch they could also be used against other ships. At least, assuming they got close enough for that to be possible.

In spite of all that extra size, the carrying capacity of the Leviathan-class was not massively larger than what other carriers could achieve at the time. While they could comfortably accommodate three Army Expeditionary battalions, complete with their armored and aerial support, this could only be done by substituting out the entire space fighter airwing and offloading their supplies and logistical support to another ship. It was more common to see a single battalion embarked instead, with the freed space going to up to 18 space fighters, 12 atmospheric jet aircraft, and six dropships to allow for greater utility, both to the soldiers and the ship. The Leviathan also had berths for up to three subvessels that massed up to 7,000 metric tons, which could either carry cutters or orbital landers.

As conversions, the Leviathans had a highly unusual frame organization that could be charitably described as "chaotic". Their hulls were divided into two distinct layers distinguished by their frame density, with the inner core (which was largely unaltered from the original cruiser plans) utilizing considerably larger and more steel beams than that used for typical carrier construction. As a result, critical systems housed close to the ship's center such as the reactor, AI computer spaces, and the fleet command facilities could continue to function intact even if the entire encompassing hull had been totally breached in all compartments. Such a protection scheme was akin to building an entire second ship within another, with all the inefficiencies and financial cost that came with it, and could be done better by simply building the entire ship to cruiser build specifications instead, and so was never replicated on any other ship class before or since.