The events that happened before, and which caused the Neoarctic Age are shrouded and corroded. The few things that we do know about the Great War are from personal accounts saved in personal hard-drives, and although often biased, these allow us to reason the cause of this catastrophe.
At the time it was not called the Great War, in fact there seems to have been many stages, these stages were each termed 'wars' or 'operations'. Worldwide power-struggles were being held and were often covert. A system of governments were set up, each declaring an impartial system while being corrupt within. The monetary system was another arena which caused a massive divide in lifestyle between the rich and poor. Many accounts claim that the corporations had control and used capitalism as a weapon, divider and harness.
Nearly every pre-war home excavated has contained at least one personal computing device, as well as a 'television' or tv. Some tv's predate the War by nearly a century, having been embedded into culture and society. Through this media, and multiple industries which support it, dominated and pacified the majority of the population. In fact it has been found that a "pop culture" existed which served as a distraction and commodity.
While distractions and sales dominated the media, other issues were easier to avoid and ignore. While the groundwork was being done by pre-Corp military the media was tasked with the job of hiding the disagreeable facts. They did it fairly well, even to the extent of misinformation on social networking. By the beginning of the 21st century an ever-increasing awareness began to spread which triggered the first of many changes that century.