Because the Hierarchy has vast military experience from invading and destroying other planets in the universe, the human race is not able to withstand their forces. Before their landing, observatories and scientists on Earth gave warning of aliens but the human race, as a whole, is not able to organize a unified military front against the alien forces. Universe at War: Earth Assault, begins in the year 2012 when an alien race known as the Hierarchy lands on Earth to strip-mine the planet.
