Segmentum Pacificus

Segmentum Pacificus is one of the Imperium's five Segmentum Majoris, the western cube whose fortress is Hydraphur and whose famous bills are the Macharian Crusade and the Night of a Thousand Rebellions.

Sabbat Worlds, Macharia, Colchis, and later Leviathan's Sanctum war all sit in this half of the map. Nova Terra once claimed the whole Segmentum; Macharius took a bite the Heresy then spat out.

Segmentum Pacificus still matters as Terra's western wall, not as a mashed Tempestus hybrid. Unofficial notes keep a null parent and skip the duplicate id segmentum-pacificus-segmentum-tempestus.