Alliance-class heavy battleship (EXverse)

Essentially a battle-oriented version of the , the Alliance-class heavy battleship - hull classification symbol: BB - is a powerful line of heavy-tonnage vessels capable of ship-to-ship combat and capital ships escort. Developed by the renowned Sinoviet Heavy Machinery as a response to the threat posed by Covenant heavy capital ships such as and , it was a massive effort for humanity, since it never made before something of the kind; overshadowing even the more powerful and its battle-focused prototypes in terms of kills related to its size, Alliance-class scared Covenant fleetmasters and even the Prophets, worried about the possibility that humanity could have filled the technological gap before its complete extinction and so being able to launch a counterattack. However, while its number built were more than the majority of stopgap model introduced during the war, they were still not enough to counter the sheer number of Covenant vessels.
Its building had much influence also inside the Navy itself, which definitively became in favor of battleship-type vessels. Shortly before the attack on Camber, NAVCOM decided not only to upgrade all existing Alliances, but also to award Sinoviet forty more vessels, so as to replenish combat losses, but the order would never be completed due to the fall of Meridian in 2551, which led to resources' shortages and to stop production of the heaviest UNSC ships.
Only two ships survived the war, being still on the frontline by 2558, but without a proper replacement in sight.
== History ==
=== The Massacre of Outer Colonies ===
When the Covenant Empire begun to strike human colonies, the UNSC Navy found itself unprepared: the alien overwhelming firepower couldn't be matched by even newer warships like Marathons and Paris. Traditional carrier strike groups, like those employed during OPERATION: Trebuchet, were ineffective due to the low durability of UNSC ships; Archers were neutralized by Covenant shields, so the only way to destroy alien vessels was employing MACs extensively. However many of the UNSC ships had old MAC systems and these had a long charge time, which forced fleet commanders to use heavier ships as long-range artillery gunfire and smaller ones in flanking maneuvering roles.
Since the beginning shipyards were charged to conceived and build more powerful vessels in order to contain the alien threat; helped by ONI and its special divisions, they tried to design and construct cutting-edge vessels, in order to move close to the alien technological level. However results were far inferior to what expected, because humans had little understand of Forerunner technology - which could have helped in the fight - and, at the same time, reverse-engineered processes took much time to be completed.
At that point naval shipyards took a different path: upgrading warships already in service and building newers by reusing already designed superstructures. This took lesser time and became necessary when the Navy started to suffer heavy casualties in each battle it fought: Vice Admiral Cole, who was considered the lifeline of human species, win every battle he took part, however he always suffered many losses; so replenishing his fleet began to be the priority, and the above-mentioned path was the only one effective to do that.
Vessels like Liberty battlecruisers showed to be able to penetrate Covenant's shielding with easy and, in theory, punch the hull as well, however they were badly armored; Punic-class supercarriers, while the most powerful vessel fielded by the Navy at that point, they were too few, the same happened for the Valiant-class. Only Nebula battleships were highly effective...
=== Consolidation of battleship's doctrine ===
Nebulas particularly were interesting, since they were a type of ship never employed by the Navy before than. These battleships were long theorized by naval officers, but their doctrine had never fully developed due to the lack of proper targets: cruiser-grade MACS were already a waste of power, as the largest type of ships deployed by Insurrectionists were frigates, so they were Punic-class' MACs; due to this only a rough doctrine was conceived before the Covenant started to slaughter human colonies, partially focus on how to use them and in what circumstances.
After UNSC started refitting its ships because of the threat posed by Covenant, battleship's doctrine became the NAVCOM's primary goal in order to improve the fleet's firepower. Liberty-class' successes convinced flag officers that a similar ship, but having increased armor, could be a good bet. Nebulas showed that human technologies were far inferior to Covenant ones, but with tactical inspirations and impressive strategies, it could be possible defeat alien fleets; nonetheless Nebulas lacked considerable secondary and tertiary armaments, as the so-called light battleships had a ship-killer role; in fact their MAC systems were among the most powerful ship-based versions in the entire UNSC arsenal, but at the cost of long cooldowns.
At that time, naval officers understood that they need also a heavy battleship. According to the doctrine, this heavier version needed a more diverse armament which could allowed these ships to engage multiple targets at once while being capable of sustain extreme damages from both kinetic and energy-based attacks. The MAC system wouldn't be necessary more powerful than that fitted on lighter battleships, but it needed to outgunned cruiser-scale MACs and it had to be powerful enough to cripple at least all type of Covenant cruiser in a volley.
Another requirement was the short time needed to design, construct and launch the first of the class. Due to this, only already designed hull were suitable for building around this vessel, but only one was perfect for the task...
=== Sinoviet makes history ===
Sinoviet Heavy Machinery, after upgraded and started to rebuild them, decided to put all efforts in a heavy warship capable of directly engaging the same Covenant opponent and win. Many challenges had to be face, first of all an already airframe built, but Sinoviet, which had lost its founder since not long ago, was surely of what it had to be constructed.
Three of the most skilled architects were charged of this project. They found that the only airframe useful for the project was belonged to the for three reason: a durable superstructure, right size and the fact that was the latest airframe in service with the Navy, being launched in 2521. The others, even if belonging to other shipyards, weren't suitable: too small or too old, too weak or to heavy. Anyway, as soon as the airframe was chosen, the three naval architects started to design every system of the ship: it was the 2530.
But the problem came when they move on weapon systems. As they knew they were conceiving a heavy battleship, its armament should have dwarfed all existing warships, except that fitted on the . Rejected Super MACs due to being too powerful of a vessel of that size, the architects looked at the super-heavy MACs installed aboard Liberties, which proved to be the greatest addition to the fleet since the born of the Super MAC roughly fifteen years prior: essentially an oversized version of Vindication-class' MAC gun, it was capable of destroying a CCS battlecruiser in two shots and with shields up and they required much power to work, but the engine designed by Starwerx would resolved that issue.
However architects felt that those MAC guns weren't suitable for a battleship due to two reasons, both concerning the MAC system. One one hand, Vindications had cruiser-scale MACs, but these were optimized by fusion reactors; this solution made Vindications able to unleash a firepower well over its size, capable of rivaling Liberties one; on the other hand, Epoch airframe had a major drawback that architect didn't explore when they accepted it, that was not being suitable for more than one MAC.
These reasons led the architect's team to review partially the idea; so they decided to downsize the 's Super MAC and incorporated it on the class. This choice happened because that model of Super MAC had extra power capacitors which decreased considerably the charging time of the gun and it was more powerful than the model fitted aboard ; but since it wasn't enough, because at that point two MACs were considered standard to survive against a shielded vessel, special magnetic field recyclers were fitted alongside: this trick granted two slugs fired at once, so appearing that these battleships had two spinal guns instead of a single one. Many contested that choice, because according to them the Moncton class' Super MACs were powerful enough for purposes that would have filled by this battleship, other than being lighter; but architects went on their ideas and they installed one super-heavy MAC directly derived from those located around Reach, moreover it was the only human colony to host Festung-class OWPs.
Another flaw, according to many, was the lack of intermediate weapons between naval coilguns and point defense guns such as Sentry autocannons, which made Alliances too exposed to air strikes. However architects replied that they were conceiving a heavy battleship, a warship capable of going toe-to-toe with heavier Covenant vessels, so giving anti-air cover wasn't among its roles.
Anyway, designing and testing special recyclers took almost two years, which further delayed the launch and made upset part of the Naval Command. But when the ship came out from Reach shipyards in 2533 and it started to be tested, results were so impressive that the Navy thought to have the solution to all problems in its hands. Despite it was very powerful, considered the average of UNSC vessels, the excitement devalued the still existing technological gap.
=== Alliances at war ===
Alliances were soon deployed in every battle the Navy were fighting. Their baptism of fire happened during the last year of fight around Jericho VII: the UNSC Alliance and UNSC Art of War were just commissioned and they were deployed in that battle; however, the lacking enough information about how to use them and what strong points they had led those vessels to be destroyed during the last Covenant offensive. Nonetheless, they had enough time to do five kill each, among them even a .
By that point Fleet Command decided to assign to every fleet no more than four Alliances, to avoid excessive casualties, but usually they took part to every major battle from 2535 to the end of the war.
However, reports from the frontline saw that Alliances could be further improve, and that DFD-2 engine's output was on average, something not acceptable for what it was known as the most powerful vessels of the Navy at the time. Despite this, the class inspired the , a vessels even more powerful which could be defeat a CAS easily, but the project didn't went on after three prototypes due to the lack of proper resources, drained by the Project: OUROBOROS.
After Admiral Cole made the ultimate modifications to his flagships and these were shortly after transferred to all Valiant cruisers, Naval Command saw the opportunity to upgrade all existing vessels, starting with Alliances. However, other than simply upgrading, NAVCOM awarded Sinoviet forty more vessels to replenish combat casualties. The Flight II saw the implementation of Mark 33 Spitfire naval coilgun batteries in place of some Hailstorms, which were also upgraded but decreased in numbers; anti-air deficiency were in some ways resolved by fitting the newly-developed M961 Fortress point defense gun: seventy millimeters in caliber, were more powerful than any existing anti-air gun and they had a good rate of fire. Even systems were upgraded, and the new Typhoon VI IEWS was implemented, which featured a plasma torpedos-jammer alongside traditional electronic warfare array.
These upgrades bolstered Alliances effectiveness, soon showed during the Siege of Atlas Moons. Despite this, Sinoviet had production delays due to resources shortages and the loss of additional shipyards, which granted streamlined production; it was for these reasons that at the time of the Fall of Reach, in 2552, five vessels were still under construction, and the loss of the fortress world meant also the loss of those five vessels.
Seven battleships took part to the final engagements of the war in and around Earth. Although they engaged Covenant ships in three separated moments of the battle, they were all destroyed but after causing heavy casualties. Other two were stationed around the vital world of New Carthage, and they were about to go to Earth to reinforced human defenses, however the death of the Prophet of the Truth and the help of the Sangheili fleet prevented so. Therefore, these two survived the war.
== Overview ==
=== Hull ===
Being 2,563 metres long, 817 metres wide and 552 metres tall, it is as large as a . However it is heavier, weighing 50 million metric tons; this is due to huge amount of weapon systems and the installation of a single super-heavy MAC, instead of a light one. Besides, exterior design is identical, featuring large slanted wings which house Breakwater and Hailstorm coilguns, as well as some of the point defense guns.
Interior layout is similar to the Epoch one; as such, it possesses a recreational room reserved to officers located under the bridge, which is an exclusive club not open to NCO and sailors. There are three types of crew quarter: those reserved to officers, those reserved to NCO and sailors and those reserved to non-Navy personnel. First ones are large, single dorms with a number of privileges, such as a desk and a chair; second ones are small, double dorms with only the toilette; third one belong to marines and other non-Navy personnel but, in truth, are identical to those belonging to NCO and sailors. Anyway beds are more comfortable than those found on Epochs, due to the Alliance greater relevance. Two gyms are fitted, one on the prow and the other amidships; near the first one there is also a large, well-equipped kitchen.
There are two cryo-bays, one located near the engine room, and the other near the bridge; armories are four, two next to cryo-bays, one on the prow and one amidships. One single hangar is fitted on the prow: enlarged compared to the one implemented aboard Epoch, it can host six dropships and two starfighter squadrons, granting air cover in case of emergency. Some of clamps and access umbilicals used on the Epoch by large starfighters are still present, which allows the ship to carry some more starfighters without subtracting space for ammunitions. The others hangars are simply closed: space left is covered by ammunitions for the impressive quantity of weapons carried.
Finally, 3.58 meters of Titanium-A2 armor. Some captains and flag officer, as other did before, layered the armor with some heat-resistant materials, such tungsten or tantalum, otherwise with refractory compound such as tantalum carbide or tantalum hafnium carbide; all these hand-made modifications improved, in some way, performances against directed-energy weapons, granting much more survival capabilities.
=== Propulsion systems ===
=== Crew and complement ===
1,100 sailors are required to operated a such ship; in case of emergency, 820 sailors can man it, but a number lower than that can compromise the efficiency of a crew. Due to the relevance of an Alliance in a fleet, these ships are crew by the most experience and skilled sailors and officers, who increase the ship's operability beyond their effective capacity. Initially, a captain could be assigned after at least roughly eight years of service as a capital ship's commanding officer; however, both number built and the impressive casualty rate meant that the FLEETCOM was incapable of doing so, which forced it to modify prerequisites requested: after the fall of Camber in 2537, a captain could be assigned to a heavy battleship if he/she have proved great skills in command positions or after five major battles, but the years of service remained as an alternative although decreased to five. Other officers, instead, were chosen since the beginning on a five years of service-basis in whatsoever position or if they proved to be skilled enough - often marked by a field promotion. These conditions are required for NCOs and sailors as well.
Two hundred marines are accommodated for security purpose. Other than them, six Pelican dropships and two air squadron can be hosted in the hangar, namely eighteen starfighters. Some ships carried F-41 Broadswords instead of more traditional C712 Longswords, due to their impressive dogfighting capabilities joined by a smaller airframe; anyway the Navy never made large use of Broadswords until the end of the war, so restricting these powerful starfighters only to some vessels.
=== Armament ===
The class enjoy one of the most powerful armament fitted onto a UNSC ship during the war. Since it was conceived as a battleship, Alliance-class sports more coilgun batteries but less missiles than cruisers and carriers.
The primary weapon system is the Mark VI, Super-Heavy Coil - 92R7J1 MAC; differently from the Mark VI installed aboard six year prior it is basically a downsized 's Super MAC; over the half of the ship long, it is made up of hundreds of asynchronous linear induction motors, which all line the barrel of the weapon; extra power capacitors and special magnetic field recyclers are fitted and they are the same later mounted aboard the refitted UNSC Pillar of Autumn: thanks to them Alliances can not only decrease charging time about the half, as its reactor's output couldn't match OWP's power generators, but also to fire two slugs in a row. This trick was necessary, as the airframe couldn't accept two MACs without being completely changed, and two slugs were the minimum requested to destroy a Covenant ship, no matter size.
This MAC system can employ a wide range of slugs fired at two hundred kilometers per seconds when fully charged, from shield-piercing rounds to specific-orbital bombardment rounds, and four types of shells by weight: 1,800, 1,200, 800 and 500 tons. The first one is the most powerful round available for non-Super MACs and it is capable of destroyed an without the help of Archer missiles, even if underpowered: first shell disables shields, the second one gut hull; however it required at least two minutes to be fully charged - reduced to ninety seconds in Flight II. Second one is less powerful, capable only to disable ORS' shields, but it is enough to destroy a ; it required one minute and a half to be ready - fifty minutes in the later Flight. Third ones and fourth ones are the lightest shells employed by the Alliance and are enough only to destroy a , but they are fired every forty seconds - reduced to thirty in Flight II.
The MAC guns are supplemented by four Mark 25 Breakwater naval coilgun batteries. These powerful weapons can easily destroy a unshielded CCS in a few seconds thanks to its 7-tons slugs, which are fired at thirty kilometers: as such this Breakwater's model can compete with UNSC frigates' spinal MAC; besides, Mark 25 have a new stabilization system which improves accuracy at long distances. In the first flight, however, Breakwaters could fired every thirty seconds and together with MACs only if all power were redirected to weapon systems: that became a problem, as in order to destroy a an Alliance needed that all batteries could fire simultaneously, achievable but at the cost to be immobile. In the second flight, thanks to overpowered engines, this problem no longer existed, and when not requiring a combined shot Breakwaters can fire every fifteen seconds, halving time. Two batteries are found on the prow, while the others are located on the wings in place of clamps and access umbilicals utilized on the Epoch by large starfighters.
Second flight added also eight Mark 33 Spitfire naval coilgun batteries; an intermediate weapon between Breakwaters and Hailstorms, Spitfires are dual-barreled coilguns capable of firing 3-tons slugs at fifteen seconds every five seconds at fifteen kilometers per seconds. This addition was necessary in order to maximize Alliance-class' effectiveness, diversifying armament to hit different multiple targets suitably.
Tertiary armament is made up of seventy M58 Archer missile pods, which are fitted onto the hulls; each pod contains thirty general-purpose missiles, for a total of 2,100 ordnances, and they can be used with various warhead options.
The anti-air weapons systems was made up of 42 M803 Helix point defense guns, a reliable gatling-type coilgun capable of shooting down starfighters of any size. However the lack of intermediate point defense guns meant that a fifty millimeters-system was inadequate: for this reason, in Flight II 38 M961 Fortress point defense guns were fitted: a new systems, later made perfect for the , which fires seventy millimeters bullets instead of the common fifty millimeters. It has a high rate of fire and a good accuracy, other than much more effectiveness against larger dropships.
Finally, three Shiva-class nuclear missiles for strategic strikes against spaceborne assets.
== Role ==
Their primary role is ship-to-ship combat. However it is not intended to operate alone, as at the time of its building resources were precious: as such, until some years after the end of the war, losing one of these ships was considered a great loss, even more than a .
Due to this, Alliances is used in large fleets, however very few of them had more than four heavy battleships throughout the war. During the countless battles against Covenant fleets Admiral often chose using Alliances as flagship's shields against plasma weapons, drawing fire while capable of responding thanks to their armament. Others, instead, used Alliances as frontline vessels alongside cruisers, allowing destroyers and frigates to flank enemy ships; otherwise, they were utilized as escort of carriers, protecting each other, carriers with starfighters squadrons, and Alliances with weapon systems.
However, its major setback is lacking of intermediate weapon between coilguns and point defense cannons such as Sentry autocannons; this forced naval officers, during the war and after, to use anti-air cover-oriented escorts, even if after Flight II Alliances were fitted with more powerful Fortress guns. In addition, the small bridge didn't allow a complete control of the fleet, nor architects foresaw command-and-control purposes, so they were never used as flagship, even in the post-war years.
Nonetheless, these ships can theoretically operated with a small group of ships, as they have a good starfighters complement which allows them to counter enemy fighters. However, as said above, their costly building meant that only after the war the two remaining Alliances could be seen as escort of small flotillas.
== Ships of the line ==
Name 	Hull Classification Symbol	Commissioned	Destroyed or retired	Notes 	 	
Flight I 	Flight I 	Flight I 	Flight I 	Flight I 	Flight I 	Flight I
UNSC Alliance 	BB-161 	2534 	2535 	Lead ship of the class. Destroyed above Jericho VII	 	
UNSC Art of War	BB-162 	2534 	2535 	Destroyed above Jericho VII. 	 	
UNSC Empire 	BB-198 	2536 	Still in service 	Took part to the Battle for Earth 	 	
Flight II 	Flight II 	Flight II 	Flight II 	Flight II 	Flight II	Flight II
UNSC Nelson 	BB-176 	2537 	2542 	Destroyed during the Battle of Alluvion