Great Silence

The Great Silence was a cataclysmic event that resulted in the destruction of Chikyū, the homeworld of Yamatai's pure Humans. The final stage of the cataclysmic war with the alien Hanran, the Great Silence was the end of humanity's home and marked the start of the Final Wave of Human Colonisation.

It is because of this blasphemy against the Gods' greatest creation, Chikyū, that the Divine Mission was revealed to the Empress of Yamatai to eradicate or subjugate all non-Humans, as the Gods believe that the injustice against them and their chosen race must be avenged.

Operation Ōka
Operation Ōka was initially a contingency plan first proposed by the United Nations in the event that the Hanran managed to breach the Oceanic Defence Lines and threaten the island nations. Essentially, as many civilians as possible would be evacuated from the planet to allow total unrestricted warfare across the world. With the relentless onslaught by the Hanran, however, Operation Ōka was unable to be carried out in the method envisioned.

All military forces were to adopt a defensive stance while all remaining resources were to be devoted to constructing more refugee starships, in addition to the transport ships already in use to travel to the colonies. As many people as possible were to be transported to the colonies while military forces bought time for the evacuation with any means necessary, including the use of weapons of mass destruction.

The entire effort took three years to send two billion people off-planet. By this time, it was no longer possible to sustain a defence and only the final island strongholds like Jingpo, Nusantara and Yashima remained. There were too few military forces and resources remaining to carry out the mass offensive as planned, and all the remaining forces could do was to defend the remaining island nations.

Great Silence
With the mass usage of weapons of mass destruction, large areas of the planet were no longer habitable. All remaining military forces struggled to defend just the island nations, which were also increasingly damaged by the ecological disasters unleashed by the mass use of nuclear weapons.

Eventually, the Hanran overcame Jingpo and began invading Nusantara and Yashima. It was finally admitted that there would be no hope of retaking the planet from the abominable non-Humans, and the remaining humans on the planet evacuated in the Final Wave of Human Colonisation. Millions were left behind, fighting to buy time for their brethren to escape the doomed planet.

Finally, in the year 2050, all signals from Chikyū ceased. Humanity's homeworld was no more.