Marathon-class heavy cruiser

The Marathon-class heavy cruiser (: CA) was the primary classification of cruiser used by the before and during the. Beginning production in, the Marathon was introduced to combat the threat of the ever-worsening. While not the largest or strongest warship created by humanity at that point, the Marathon was widely believed to be the most balanced. It's incredibly light design allowed it to close the distance of any target, while its modest 191 centimetres of armour and heavy armaments allowed it to disable or destroy all but the largest spaceborne vessels. When coupled with its extensive command suite and modular hull structure, it allowed the cruiser to adequately fulfil any required role at a far cheaper cost than its competitors.

Immediately after beginning production, the Marathon quickly became a desirable position among UNSC captains. It quickly proved its worth, outgunning every ship smaller than itself with ease and became instrumental in nearly every major conflict during the Insurrection. When the attacked humanity, it just as quickly displayed its vulnerability to Covenant weaponry. This weakness led to production slowing down as alternative designs were tested, but the sheer number of cruisers constructed meant that they served at nearly every major engagement of the War. Even after being pulled back to command the defensive fleets of the, nearly every member of the class was lost to enemy fire, resulting in the quickly replacing the Marathon as the UNSC's new mainline cruiser.

Development
Somewhat surprisingly, the initial design of the Marathon-class was created around the same time as that of its predecessor, the Halcyon-class cruiser. The pet project of Lorraine Reyes, co-founder of the, the Marathon was envisioned to be the partner of design; whereas McLees would produce a ship which could withstand the fire of a far larger ship and the command capacity, Reyes' concept would provide the firepower, speed and adaptability. Both ships could carry more squadrons than any other class of cruiser in the past. Between these two designs, the pair hoped that the UNSC would replace their entire complement of larger warships. However, when McLees submitted the designs of his light cruiser to the UNSC for testing in, Reyes did not, still believing her design to be a work-in-process.

After the trials of the, both Reyes and McLees were disappointed to learn that the UNSC would only order eleven vessels. The admiralty cited that while the design was exceptionally durable, its high cost, slow speed and unacceptably weak weapons limited it to the role of a tank in fleet combat, even with its pitiful excuse of a command suite. While McLees addressed these critiques in the Halcyon 's second block, of which the Navy would order a further thirty-nine vessels, Reyes made further modifications to her design. The prototype was vastly up-armed, given sixty-five additional missile pods and thirty-eight point-defense guns. As there would be far too few Halcyons produced, the communications array and sensor were replaced with top-of-the-line models, and more powerful reactors gave it incredible endurance even in the heat of battle. The final upgrade would be from McLees, who redesigned the superstructure to allow it to take more hits while expanding the hangar. This improved model was christened the Elysium-class, and while easier to construct it too would only enter a limited production run, although at 148 orders it was more successful than the Halcyon.

Development on the design would halt for a time, as both McLees and Reyes pursued other projects. After the blueprints for the were bought out, and upon noticing its mid and aft bore a striking resemblance to the Elysium, Reyes redesigned both ships into sections. By sharing superstructure and components, the Elysium could finally be made cheaper, constructed far more rapidly and could be given a more modular design. Despite this, there were differences in each class' superstructure; the Valiant was interlaced with internal plating, while the new Elysium block was made lighter and had space for hangars. The only drawback was that most of the weapons had to be stripped to streamline production. To further cut costs, the Elysium 's expensive equipment and components were replaced with cheaper alternatives. The last change was that all point-defense guns were upgraded to the more effective and it carried an additional MAC gun. All these changes made the new block easier to construct, cheaper and better suited the role of mainline cruiser - all reasons proving that the new design should be renamed. In, the UNSC allowed the construction of a prototype for trials, christened the. The capabilities of the new cruiser had so impressed the admiralty that they immediately cancelled orders for both the Halcyon and Elysium, intending to replace them with hundreds of the new cruiser.

"They may not be as numerous as its sibling, but they are a full league above your typical heavy cruiser. They have more guns, its better protected, carries more fighters and has higher-quality equipment. All considered, its an upgrade."

- Vice Admiral Roger Reeves, captain of the UNSC Tsushima Straights.

The sister-class of the Marathon retooled into a command variant, the Elysium-class missile cruiser was originally introduced in 2511 to serve as a replacement to the Halcyon-class cruiser. While visibly identical with the exception of the additional missile pods and, this variant is built with better quality and more expensive equipment, allowing it to be tougher, stronger and more reliable. However, its the ship's more expansive bridge and powerful communication array which makes has given it notoriety among the fleet, with many famous heroes choosing it as their command ship. Unfortunately, all these improved features has made the Elysium much more expensive than the typical Marathon, leading to nearly all members being transferred to the for assignment. The class was rendered extinct in 2552, after the sole remaining member, the UNSC Lepanto, was destroyed.

Salamis-class cruiser-carrier
A slight modification of the base Marathon, the Salamis-class cruiser-carrier was created in response to the perceived loss of carrier support that would result if the Covenant War dragged on for too long. To achieve this, most of the base cruiser's superstructure was redesigned to allow it to carry a larger complement, while smaller hangars capable of accommodating a single Longsword replaced many of the ship's armaments. This allowed the Salamis to carry a Wing of Longswords (77 strikecraft) or equivalent. The bridge was also expanded to better coordinate the strikecraft, with multiple transceiver/receiver networks allowing it to handle different communication channels simultaneously. Although noticeably faster and cheaper, the Salamis is rarely seen as the UNSC were able to maintain a number of pure carrier vessels.