The Fall of Cadia marks the destruction of the Imperium's most vital fortress world, an event long thought impossible and mourned as one of the darkest hours in its history. For ten thousand years the planet had stood sentinel over the Cadian Gate, the stable channel by which the forces of Chaos issued from the Eye of Terror, and its warrior-people were bred from birth for war.
During the 13th Black Crusade, Abaddon the Despoiler brought against Cadia a host of unprecedented size. The decisive stroke came when a captured Blackstone Fortress, an ancient star-fort of terrible power, was driven down into the planet itself. The Cadian regiments and their allies fought with grim discipline to the last, but the world was doomed; its surface convulsed and broke apart beneath them.
As Cadia died, the phrase that had defined its people, that Cadia stands, gave way to a bitter new truth. The planet's ruin helped tear open the Great Rift, unleashing warp storms that swallowed whole sectors. Survivors were scattered into the void, carrying the ash of their home and a hardened resolve. The loss was not merely of a single world but of the strategic linchpin that had contained Chaos for a hundred centuries, and the galaxy would never again be whole.