The Cadian Gate

The Cadian Gate is the most strategically vital region in the galaxy, the single stable warp corridor leading out of the Eye of Terror into the wider Imperium. Every Black Crusade that has ever marched from the great rift has been forced to funnel through this narrow passage, and for ten thousand years the Imperium poured its strength into holding it.

The linchpin of the Gate was Cadia, a fortress world without equal, its every surface bristling with bastions and its population trained to soldiery from birth. Generation after generation of Cadian Shock Troops, the finest regiments of the Astra Militarum, stood their ground against the daemon-hordes and the Chaos Space Marines that hurled themselves against the line, and for all that time the Gate held firm.

Then came the Thirteenth Black Crusade. Cadia broke, shattered by the will of the Archenemy, and the world itself was destroyed. With the bastion gone, the Great Rift split open and the passage stood undefended. Though the Imperium fights on to hold the region, the loss of the Cadian Gate remains one of the darkest hours in human history, the moment the floodgates of damnation were thrown wide.