X-Day is the given name and date for the Chronos operation in which Chronos actively declared war on the entire world, and launched a global assault on every major super-power and nation throughout the globe; destroying them all in less then two days.
X-Day was also the given name of the Operation itself (Operation X-Day) in which Chronos had secretly sent their Zoanoids to infiltrate a number of countries and to obtain positions of power, in combination with their troops to subdue the worlds military completely. This was done to not only destroy the human military forces from the inside out, but also to divide and conquer.
X-Day is a pivotal day in the story in which the entire world was suddenly attacked unannounced by the Chronos Corporation and their Zoanoid armies. The day was said to be disastrous for human kind, with casualties being catastrophic. The exact details entailing the operation are sketchy as the story never fully explained all of the events that transpired during it. However, it is referenced to a lot and after the event occurred, Sho and his friends were forced to change their battle strategy from fighting against a secret society to fighting against a world controlled by one.
During the operation itself both Guyvers were not present, as they had been transported across the world after the battle at Relic's Point. Because of this they were both unaware of the event and were unable to assist or prevent X-Day from occurring.
The operation took one whole day in the east, but two in the west, to conquer (due to the nature of dates, calendars and the sun rising); however it is widely accepted to have been one whole Earth day. Chronos quickly moved in and divided the world into sectors which comprised over a large continent that were watched over and controlled by a Zoalord and various small regencies, or areas ruled by Directors. Most were easily conquered although Cabraal Khan's sector lagged slightly, due to resistance fighters. It is known that the American soldiers stationed in the Middle East continued to resist and fight the Zoanoids and Chronos despite the world being conquered by them, and used their nuclear weapons against the attacking Zoanoids. However, it was to no avail due to the Dragonlord's presence and they were swiftly killed afterwards.
It is also known that all military powers and branches were over whelmed swiftly before they could deploy their forces. A large battle took place in the North Atlantic Ocean, with human and Zoanoid Naval forces. Aerial battles took place over large cities, including dogfights with fighter jets, and flying Zoanoids, who managed to cripple Air Forces. While armies, and marines were sent to protect the cities and people, but proved to be no match for the superior power and might of the Zoanoids. The day concluded with Archanfel's Zoalords bowing to him as he watched the sunrise on a new day, knowing that Chronos now ruled supreme.
The day is recorded in the manga as being 17/08/199X, though the anime had it occur closer to modern day.
Prior to Operation X-Day, Chronos was a secret military organisation hiding as a corporate company when they initiated X-Day and so there were concerns that they would enforce this militaristic view on the world once they held power. The world though was surprised to find that this wasn't the case, at least with some of the sectors. Instead Chronos focused humanities efforts on restoring environmental damage and the population that was lost during X-Day.
In the Aftermath of X-Day they eliminated all political boundaries. National debts were wiped out, poverty was eliminated and there was in general a redistribution of the worlds resources so that all of the sectors could benefit from Chronos's technology. They initiated strict environmental laws to ensure that environmental degradation was stopped and created curfews. Patrols monitored the people and sought out "terrorist" or people they deemed a threat to their own rule (anyone who fought against Chronos, or launched political movements against them). They also used their technology to cure many diseases including cancer and many STD's; and controlled the media outlets and what information was given to the public.
While it is known that some sectors did not force people to become Zoanoids it is unknown if other sectors did. However, it is known that Chronos began a massive campaign that romanticized Zoanoids and used propaganda to have people willingly choose to be optimized into Zoanoids. This propaganda campaign included the Zoanoid rock band Jukadan as well as advertisements depicting Zoanoids as great potential for mates. Other advertisements were shown to increase self-esteem, giving people a new purpose or destiny, while guaranteeing them a new future and a better world. To culminate this plan, Chronos advertised that only Zoanoids could be crew members on their Ark and only Zoanoids would be allowed to travel on it.
Ultimately there was a marked shift in the perceptions of people and Zoanoids, people either accepted and became a Zoanoid or were forced to due to the fact that the world had changed around them, and the only way to benefit in the new society was to be optimized into one; which was Chronos's plan all along. Because of the huge political pressure, propaganda, people's lethargy and the movement to become Zoanoids, people began to see Zoanoids as a part of natural life and not as the monsters that destroyed their world.
The details of the known battles have not been revealed yet, however the following is a list of battles that are known to have taken place:
- The Battle of Tokyo
- The Battle of Beijing
- The Battle of Moscow
- The Battle of Paris
- The Battle of London
- The Battle of the North Atlantic
- The Battle of Washington D.C.
- The Battle of the Middle East