Hydraphur

The Segmentum Fortress of Segmentum Pacificus.

Hydraphur is an Earth-like world on the edge of its Segmentum. While often described as a forge world, the planet itself is not a holding of Mars, but rather the Administratum and the Ecclesiarchy. Hydraphur is encircled by an artificial ring of staryards which serve as the headquarters for Battlefleet Pacificus.

During the Plague of Unbelief Hydraphur yielded to the forces of the Apostate Cardinal. Many ships of the battlefleet were lost in Bucharis's ill conceived attack on Fenris.