For centuries, the galaxy flourished under the benevolent aegis of the Empire. Yet however great the Empire grew as it spread across the stars, it knew that others had gone that way before: interstellar travel depended upon a wormhole network wrought from the fabric of reality with powers beyond any but its vanished Builders. In time, these Builders came to be revered by some as gods. And as so often before, disputes about their will led to war.
The Guardian faction sought to end wormhole travel. The forces of interstellar civilization arrayed against them, their cause seemed hopeless. But then the Guardians came to possess bulk antimatter, and used it to attack the ancient stations that stabilized wormholes. Dozens of systems were cut off from Connected Space with each attack. Galactic commerce and government were shattered.
War even came to the frontiers of the Empire. Dark centuries of uncertainty and collapse passed. Ten worlds, their only known link with inhabited space cut by an antimatter attack, have rebuilt starfairing civilization within a handful of still-linked star systems.