Conflict and CausesEdit
Near the end of the Second Extrasolar War, arms manufacturer Jorhan Stahl and military commander Admiral Orlock vied for position as Autarch. Both personalities had extensive military resources and political backing, and their contention for power escalated into a full-blown military conflict. Anticipating combat, Stahl arranged for an experimental attack vessel for carrying weaponized petrusite from Pyrrhus. The petrusite missiles were intended to be targeted toward Earth.
Following Orlock's death, a conflict emerged between ISA forces and Stahl's military and weaponry. In the effort to vanquish Stahl, ISA operatives caused the unintended detonation of Stahl's cruiser in Helghan's atmosphere. The combustion of the missiles caused a chain reaction of petrusite irradiation.
Enormous petrusite fires ignited as a result of the missiles, and propagated rapidly throughout the planet. The irradiated petrusite missiles used in Stahl's cruiser, combined with nuclear weapons and Helghan's high levels of radiation, fueled a large-scale chemical combustion. The resulting detonation caused tremendous damage to both organic life and inorganic structures such as vehicles and buildings. These fires engulfed the planet in a wave of nuclear fire.
In general, civilians had no inkling of the oncoming disaster or at what time it would strike, and for most purposes it was like any other day. Many people who were far enough away from the petrusite fires not to be killed on impact, were killed by the collapse of buildings or fallen debris.
The death toll resulting from the detonation and its immediate aftermath was estimated at one billion.
Damage from the detonation left large portions of the planet uninhabitable and largely unsafe, particularly because of subterranean tremors. These tremors echoed long after the blast and continued to stimulate large buildings and city structures to collapse. Despite this, there were a number of survivors. The civilians who survived migrated in large numbers toward the less affected zones, establishing temporary shelters and makeshift hospitals. At one of these hospitals, Vladko Tyran was said to have been born.
In the shelters, rumors began to circulate that Jorhan Stahl was still alive somewhere on Helghan, and speculation began as to how the disaster was caused. Though in Killzone: Shadow Fall, The Helghast ultimately blame the ISA as responsible for the disaster (as it was an ISA soldier responsible for the Cruiser's destruction within Helghan's atmosphere, and Stahl was believed to be dead).
The remnants of the Helghast government provided Cruisers for use as escape vessels for the survivors and moved a large number of them off of the planet. However, some civilians could not be transported, either because the vessels were at capacity or because they could not reach the evacuation site quickly enough. In particular this was an issue with elderly people and small children. Civilians in this category remained on Helghan.
Despite the eradication of all major settlements, a number of corporations continue to use the planet as a base of activities, resulting in a small, semi-permanent population. The most notable of these corporations is Stahl Arms, along with its own R&D personnel, and connected military base. New Helghan continued to use petrusite imports as a power source and an economic commodity. This compelled the refineries on Helghan to remain active and staffed despite the hazards of extraction and the refineries' distance from most consumers.
Ruins from former settlements, such as the former Pyrrhus region, were numerous and remained strewn throughout the planet. Some regions remained fraught with automated attack drones and other combat automata, which were remnants of the SEW. There was a large concentration of drones adjacent to Stahl's base, which may have been a deliberate decision by Stahl. These remained engaged long after the evacuation to New Helghan, making it difficult for non-military groups to survey the area.