The year is 2055, more than thirty years after the events of Zero Hour, Earth suffers a catastrophic collision with meteorites. The world is thrown into turmoil as large swathes of land are annihilated. Four factions, the ADF (Asian Democratic Federation), WEA (West European Alliance), WLF (World Liberation Front), and AC (American Confederacy) are at war for control of the remaining already harder to find resources as well as the preservation of their nations and geopolitical interests. Welcome to Deep Impact.
As combat technology grew more and more advanced, the US army saw a great need to keep themselves up to date with the most lethal weaponry. Although the Crusader had performed well in the conflict which led to the destruction of the GLA, recently the generals had started criticising its slow rate of fire and light armour. They argued that however well it had performed, the war that was coming would bring with in enemies with a far more advanced arsenal than that of the GLA rebels. They stressed the need for heavier armour and greater damage, at the expense of speed and size. They said they didn't care what the cost, they wanted something better.
After many months of testing with experimental prototypes, a final version was unveiled at a secret military location. Field tests on the prototypes concluded that although the tank moved slowly, in combat it was unmatched, defeating WEA and UAN opposition without getting so much as scratched. Most of the Arbiters success was attributed to the revolutionary new turret design. This new turret is able to pump out 4 shells in rapid succession, pausing only to cool the barrel of the tank before more shots are fired. It's a good thing that the US government didn't care about the cost of these tanks as although the new design is effective in combat, the new technology does come at rather a high price.