Earl Redgrave's claim that the Moon was devoid of sentient life following his discovering of the ruins of a surface based civilization (pictured left) was soon discovered to be onerous following the Bedford-Cavour expedition in 1900 which uncovered a subterranean race named the Selenites.
The insect-like race had created a relatively advanced underground society following an ancient apocalyptic war on the surface of their world (the ruins of which Redgrave discovered).
The Selenites soon found themselves at war with the interlopers from Earth as deposits of R-Matter were discovered on the lunar surface. Whilst their military technology is not as advanced as that from Earth, their innovative use of large underground creatures gives them a decided advantage in battles against the colonial powers.
The human bases on the Moon (similar in construction to the Undersea Forts on Earth) find themselves under near constant siege and mining convoys on the Moon's surface are regularly ambushed by Selenite forces.