At the dawn of the twenty-first millennium, it had been two-thousand years since the First Galactic Commonwealth had fallen into dust. It had spanned most of the galaxy, or at least the civilized parts, for a thousand years. When the Commonwealth fell darkness and strife swept through much of the galaxy. The galactic southwest faired best, proof of it was that the Republic Remnant – as it was later called – held sway over thousands of worlds there, and the Second Galactic Commonwealth rose from those worlds. Though it never reigned over even a third of the galaxy it took the name and legacy that came with it.
On the homeworld of humanity, Earth, the world was ravaged in the final days of the First Commonwealth as fleets of warships bombarded it from orbit and reduced entire continents of rubble. It had been an economic center of the Commonwealth and the last capital world. Its bombardment signaled the death-stroke of the Commonwealth. For two-thousand years the Great Dark Age gripped the galactic community until all was surprised by small fleets of ships and transhuman super-soldiers known as Ultra Marines left the world to conquer and unify all worlds around them, from system to system, sector to sector, and entire galactic regions. Under the command of the self-proclaimed empress and god of her people, the effectively immortal Mara began the Age of War. One of the bloodiest epochs in known history began.