The Strogg battled the human race for years on Earth, but as resources became depleted, Earth mounted a counter-assault on the Strogg homeworld.
Through a horrific process, the limbs and flesh of the fallen are fused with metal and machinery to create the monstrosities that are the alien Strogg. While the invasion was originally believed to be an attempt to strip the planet of its natural resources, humans soon discovered the Strogg are only after one thing: the human remains of those they kill.
In the mid-21st century, a barbaric alien race called the Strogg launched a massive invasion on Earth.