Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, and it is long believed that life may once existed or currently exist there.
After the War of 1996, Mars was first colonized by France and was turned into one of several planetary defenses established by the Earth Space Defense. The ESD Mars base was located on the eastern side of Olympus Mons, which its construction lasted for three years, and was almost finished in July 2016. The base's energy cannon was scheduled to be deliver to the Mars base before August 1.
Shortly prior to the 20th anniversary of the War of 1996, the ESD base was destroyed by the alien mothership, leaving no known survivors. The ESD was soon alerted to the loss of Mars base and becoming aware of the aliens' return.