Marathon-class heavy cruiser

"She's a workhorse, packs a hell of a punch too - too bad the Covvies liked to swing much harder."

- Captain Gabriele Kiki.

The Marathon-class heavy cruiser (hull classification symbol: CA) was the primary classification of capital ship used by the UNSC Navy before and during the Human-Covenant War. Beginning production in 2513, the Marathon was introduced to combat the threat of the ever-worsening Insurrection. While not the largest or strongest warship created by humanity at that point, the Marathon was widely believed to be the most balanced. Its 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 without being routed itself. 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 Covenant 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 Inner Colonies, nearly every member of the class was lost to enemy fire, ensuring the Autumn-class cruiser could easily replace the Marathon as the UNSC's newest mainline cruiser.

Armament
While in most respects the Marathon was considered an average combat vessel, an exception lies in its impressive level of weaponry. Possessing a variety of missiles and naval coilguns, this field was the primary reason these cruisers outclassed almost every ship before themselves; only the controversial Vulcan-class heavy cruiser could match their firepower, and could threaten the later Autumn-class heavy cruiser. This proved that the Marathon could be trusted with patrolling its own sectors without risk, and helped contributed to the large numbers of these vessels being purchased by the UNSC.

The primary weapon of the Marathon was its two new 16A8C2 heavy-coil MACs. A mammoth weapon measuring almost a kilometre in length, the 16A8C2 was capable of accelerating a 1,400-ton slug up to a maximum of 40,000 metres per second. Considered standard for the time, the MAC was nevertheless capable of instantly destroying any previous generation of destroyer and could significantly damage much larger vessels. However, before firing each MAC still required two and a half minutes to fully charge the capacitors. As a result of this, Marathons also carried a complement of lighter 600-ton rounds to fire on a reduced charge, which were usually fired just fast enough to make a clean hole through the enemy. Both rounds were made out of tungsten in a squash-head design to maximise the energy transferred onto the target. Finally, each series of coils were divided up to fire-control, allowing the crew to pick which ones were needed to fire. This was an adaptation to prevent another tragedy like Far Isle, allowing the Marathon to perform strategic planetary bombing with its MACs with minimal civilian casualties if required. Unfortunately, the concern of additional political backlash made such a feature near-useless.

Backing this up is a massive complement of sixty M58 Archer general-purpose missile pods, each carrying thirty individual missiles. The M58 is designed to fit fairly powerful warheads that weigh in at 1,650 kilograms, less than a third of the payload on the older M42. Most missiles carry a dual-purpose Electromagnetic-High Explosive munition, which deliver a devastating blast directed towards in front while also releasing a radiation pulse which can damage unprotected electronics, although specialist or mission-specific warheads can be fitted prior to combat. The missile itself is quite basic, containing a variable triamino hydrazine engine with four vectoring fins each with a miniature thruster to line up the missile to its target prior to full ignition as well as for guidance in-atmosphere. Once fully engaged, the Archer accelerates for ten seconds up to a maximum velocity of 45 km/s, making it fast and agile enough to engage all but the fastest strikecraft. Should the target be destroyed, the M58 uses a smart target-priority subsystem which ranks all nearby hostiles and ensures the swarm will always attack the most valuable enemy warship. Unfortunately, even these missiles aren't infallible, proving to be vulnerable to some fighter- and corvette-mounted countermeasures which sees them prematurely detonating or flying off-course. In addition, they are horrendously ineffective against Covenant pulse lasers, as their predictable flight path renders them vulnerable to the highly-accurate weapons. Nevertheless, their sheer potency makes them an effective weapon in the Marathon 's arsenal, especially since it can fire up to two hundred and twenty-five missiles at once.

For defence against missiles and aircraft, fourteen M910 Rampart point defence guns are installed. Maintaining a similar size and shape to a double-stacked M870B, the M910 features two crucial advancements to its product line. Firstly, the quad-barrels are a permanent design feature, doubling or even tripling the fire-rate without the usual increase in inaccuracy. Secondly, the ammunition management subroutine has been rebuilt from the ground-up, allowing it to fire subcalibre 50mm rounds against appropriate targets. They function as the turret's long-ranged ammunition, granting an effective range of roughly twelve kilometres and a maximum range of twenty-five kilometres. Beyond this, however, the Rampart is only an adequately-built anti-fighter turret; due to the heavier rounds it normally uses, its firerate has been reduced to ~180 rounds per minute for each barrel, and its barrels can only track up to 95o upwards before it must turn around. However, like all turreted systems, the standard M910 computing systems can be bolstered by the ship's "Smart" AI, increasing its range, firerate and accuracy.

Authority-class cruiser-carrier
A slight modification of the base Marathon, the Authority-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 Authority to carry a Wing of C712 Broadswords (77 strikecraft) or equivalent. The bridge was also expanded to better coordinate the strikecraft, with multiple stations for officers to coordinate multiple squadrons simultaneously. Unfortunately, the resulting ship only had twenty M58 Archer missile pods, no Spitfire naval coilguns, and only four M66 Sentry autocannons.

The Authority configuration saw the most use during the mid-war period when the UNSC's next-generation carriers had yet to come online while their Insurrection carrier power was almost depleted. The most badly-damaged Marathons were converted first, while those still in fighting condition were only turned into this subclass if there was a particular lack of carrier support in the region. Fortunately, during the late-war period, the likes of the and various supercarriers resolved these shortages, and the Authority became a rare sight during the final months of the war.

Perseus-class battlecruiser
Drawn up soon after the Marathon was introduced but only deployed after 2541, the Perseus-class was a dedicated anti-ship configuration of the Marathon. Bringing to bear much larger 33DAR3/MACs and two Mark 15 Breakwater heavy naval coilguns, as well as a vastly expanded missile complement, the Perseus traded this for almost no ability to carry fighters and limited numbers of ground troops. Unlike other ship-to-ship combat-focused designs, these cruisers do not have upgraded armour to help them take heavier fire in combat. Instead, they are intended to fire from range, with its heavy missiles protected by hiding within the swarms fired by the forward escorts.

Development
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 Reyes-McLees Corporation, the Marathon was envisioned to be the partner of her husband's 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 2510, Reyes did not, still believing her design to be a work-in-process.

After the trials of the UNSC Halcyon, 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-defence guns. As there would be far too few Halcyons produced, the communications array and sensor package 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 himself, who redesigned the superstructure to allow it to take more hits while expanding the hangar. This improved model was christened the Elysium-class heavy cruiser, 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 reviewing the blueprints for the, 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 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-defence guns were upgraded to more effective M910 point defence guns 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 2513, the UNSC allowed the construction of a prototype for trials, christened the UNSC Marathon. The capabilities of the new cruiser had so impressed the admiralty that they almost cancelled orders for every other type of cruiser, as it could fulfil nearly every necessary role with equal effectiveness.

Insurrection
The first Marathons were deployed in the core worlds of Earth and Reach, taking over from the obsolete cruisers that previously filled the UNSC's ranks. On paper, the new cruisers were already making a difference - the speed of the Marathon brought about a decrease in pirate raids within its operational area, forcing rogues to utilise more restraint in what they can attack to avoid attracting the attention of the new cruisers. However, the new class had yet to prove itself, with many captains reluctant to leave their previous vessel for one that while superior in simulations, may have a weakness in its light mass and thin armour - a worry confirmed when the rebel frigate Iliad destroyed one by tearing it in half by its thrust alone.

Such an opportunity came during the Falkirian War for Independence. For almost five years, the UNSC had struggled to pacify the well-developed colonies in the Gaelic System, as their sophisticated ground-based defences and sudden attacks from a rather large navy stunted the UNSC's efforts to reclaim the system. As a result, a new force was created and was led by Admiral Erik Magnus on the supercarrier UNSC Jupiter, who replaced Rear Admiral Sebastien Bourke due to his incompetence during the earlier campaigns. The four new Marathon-class cruisers, including the original UNSC Marathon, were instrumental to the fleet success: they had enough firepower to inflict severe damage before they jumped to slipspace, and had the agility to follow them even if they emerged hundreds of thousands of kilometres away. This put the pressure on the defenders, and would lead to their first major success when two Marathons assisted the Jupiter in hunting down and destroy the FCNS Blenheim, an Insurrectionist battleship.

With their prowess proven, the Marathon became a major part of the UNSC Navy and a highly desirable spot to command as the Navy's most modern capital ship. Their numbers increased significantly, not just because of their relatively-cheap construction and high crew requirements, but also because future support ships such as the were only designed to be compatible with the new cruiser. For these reasons, every cruiser-weight vessel starting with the lacklustre Halcyon-class were slowly replaced with a Marathon in their squadrons and fleets. They were first added to rapid-response and hunter-killer fleets, smacking down swarms of armed freighters and applying pressure to the limited resources the rebels had. So successful were they that they became the most common cruiser in the UNSC fleet by 2525, with more than 80 examples of the class in service.

Human-Covenant War
"They were some of the most effective vessels we had in the Navy. Too bad after the Covenant showed up we went through them like copy paper..."

- Rear Admiral Marcus Streep

Unfortunately, the Marathon 's best days were left behind with the beginning of the Covenant's invasion in 2525. Few actual Marathon cruisers were actually located in the region at the beginning of the war, with most being part of the Elysium subclass. These cruisers were among the only ships in the region that could reliably engage the CPV-class destroyer, which made up the bulk of the alien attack fleets. However, whereas the CPV were deployed in groups of three or more, the UNSC could not afford to keep their cruisers together; standing orders forced battle groups to flee upon detection of massing Covenant armadas and only fight above human colonies. The Marathon 's formal introduction into the war was with Battle Group X-Ray led by Vice Admiral Preston Cole, whose preference on cruiser-weight vessels with support from a relatively-small amount of frigates and destroyers allowed him to score many crucial early victories.

Unfortunately, as the Covenant's invasion fleets pushed deeper into the Outer Colonies, it became more and more apparent that the Marathon was woefully insufficient to fight the technologically-advanced warships. It was particularly easily countered by their plasma torpedoes, as not only were they guided and thus eliminated the Marathon's ability to evade them, but only certain types could be shot down. In addition, as the UNSC Dresden discovered during the Battle of Biko, only two torpedoes were needed to completely disable a heavy cruiser if they impacted the right areas. To add further salt to the wound, only the twin MACs had any visible impact on the war; Archer missiles were easily stopped by pulse laser turrets and those that survive were rarely enough to overwhelm the shields. Because of these deficiencies, hundreds of Marathons were lost between 2525 and 2531, compared to only a few dozen Covenant ships brought down by them during the same period. After this period, the UNSC High Command ordered all cruiser- and carrier-weight vessels to fall back behind the Mid-Rim Colonies for reassignment, which included the Marathon-class.