M840 Black Bear

The M840 Black Bear main battle tank, later retroactively named the Bear, is a series of superheavy tanks designed for use by the United Nations Space Command during the UNSC-CMA Cold War. The Bears were renowned for their cumbersome and maintenance-heavy nature and ultimately quickly retired - being succeeded by the M850 Grizzly MBT.

Initial contract
During their cold war, the UNSC knew that any invasion of the Outer Colonies would see defending forces hold any practical numbers and terrain knowledge advantage on the ground, leading to an increased interest in the deployment and construction of theoretical "super heavy" tanks that were able to shrug off multiple attackers at once. During the 2472 Capitol Riots on Gao, the failings of the UNSC's existing M801 Wolf Spider MBTs were well-shown during an event in which a number of tanks were deployed on the ground in the midst of a vicious riot armed with crew-served weapons and anti-tank explosives. The incident called for an investigation into the planet's arms manufacturers though no evidence of any official ties between the protestors and the companies could be found - the reports instead suggested that the weapons used by the protestors to great effective were home-made, thanks to the existing skillset of the frontiersmen who made up a significant portion of the colonial population. With this situation potentially present across any number of dozens of colonies, combined with the existing cold war with the CMA and assistance from regional paramilitary forces, it became clear to UNSC planners that their existing tank doctrines were not suitable for the emerging new landscape.

In 2475, a contract was awarded to Chalybs Defense Solutions to design a new tank to mitigate this problem, with an effectively unlimited budget. The project was rushed through to completion with the first units being tested as early as 2479, and first deployed in an official capacity in 2482. The tank was designed with the hope that it would be well-enough armoured to be able to hold its ground against superior numbers. As the project grew in scope, new features were added; multiple redundant track systems to allow the vehicle to keep fighting even after several tracks had been disabled and increased internal storage for supplies and munitions to allow the vehicle to operate for longer without resupply - an ever-present worry with operations far from UNSC logistics.

The result of the program was a vehicle which didn't quite manage to meet any of its demands; it was too heavy to be carried on a single Pelican dropship instead requiring an Albatross or Darter for deployment to the ground, massively reducing its practical range of operational capabilities. The redundant track systems only added to the vehicle's complexity with the Bears quickly becoming renowned as maintenance hogs, and the increased need for supplies meant the interior crew space was cramped and uncomfortable for working in for long durations. However, the large weight and profile of the vehicle did prove useful for firing, and the Bears quickly became known for being highly effective on the battlefield - provided they were ever able to reach it. The vehicles were often referred to derisively, and given the mocking nickname "Sloth" for their relatively low top speed and breakdown tendencies.

With the Black Bear's failures, Chalybs Defense Solutions quickly set about trying to salvage the project culminating in a series of upgrade packages throughout the 2490s and 2500s, respectively - while simultaneously beginning work on the upcoming Grizzly project intended to take the Bear's failures and correct them in a superheavy tank truly fit for the next century of warfighting. To achieve funding for the Grizzly, however, Chalybs began to run an exchange program in which older M840s could be returned and replaced or refitted with newer-generation M840Bs at no extra cost.

The M840A and M840B upgrade packages were successful in mitigating several of the key issues facing the Bear - armour was vastly reduced to give the vehicle more deployment versatility and range in the field, and eventually the redundant treads were all-but stripped out entirely to increase internal space for storage and crew. The M840B and C models were employed sporadically throughout the Insurrection.

Despite these successes, the M840B models of Black Bear were still only ever regarded at large as middlingly-effective at best, with the M808 Scorpion increasingly viewed as the better option. As such, the majority of Black Bears were sold off to planetary security forces (rebranded the M841 Brown Bear and appropriately refit) or recalled to the Chalybs facility for refitting as the M842 Polar Bear - designed for excursions on iceball worlds and arctic conditions. The Polar Bear proved much more successful than the Black Bear in specialised situations, and ultimately remained in service for several decades after the end of production for the Black Bear -even seeing action during the Human-Covenant War in a few isolated cases.

Many of the older M840s were later scrapped or "lost" - and began to show up in the hands of more organised Insurrectionist groups during the early 2500s. These renewed threats of Insurrectionist heavy armour helped push the UNSC into funding Chalybs' now-promising Grizzly project, which was formally introduced in 2519 to great successes.

F846 Uilebheist
Commissioned by the Falkirian Commonwealth ahead of their rebellion, the F846 Uilebheist was a substantially-modified form of the Black Bear. Built with a greatly-increased body, it brings to bear a shortened version of the Mark 6 Armstrong 180mm naval coilguns, fixed in place to act as a tank destroyer. However, the sheer weight required by both the gun and its ammunition meant that the Uilebheist quickly became stuck in anything other than developed urban environments, relegating it to defensive operations only.