The Segmentum Pacificus is the region of Imperial space that lies to the galactic west of Terra. The Imperial Navy fleet headquarters in the Segmentum is located on the world of Hydraphur, which also serves as the Segmentum Command's headquarters. This Segmentum was made famous by the brilliant campaign of the great Lord Commander Solar Macharius and his conquest of a thousand worlds at the edge of the galaxy. This Segmentum was also a hub of activity during the Plague of Unbelief in the Age of Apostasy of the 36th Millennium when the Apostate Cardinal Bucharius sought to carve out his own empire several decades after the death of the Arch-Heretic Goge Vandire. The Segmentum Pacificus was the site of the massive Sabbat Worlds Crusade unleashed by the Imperium of Man to retrieve the sector