During the Nova Terra Interregnum, the whole of Segmentum Pacificus was claimed by the Ur-Council of Nova Terra. Later thousands of worlds in Segmentum Pacificus were claimed by the Imperium in the Macharian Crusade, but many were subsequently lost in the Macharian Heresy.
In 999.M41, whole swaths of Segmentum Pacificus would suffer from mass uprisings by disgruntled citizens collectively known as the Night of a Thousand Rebellions. Many outlaying planets as well as key worlds such as Darkhold, Minisotira, and Enceladus are swept up in the chaos. Even the Lions Defiant Chapter of Space Marines find their Homeworld the victim of insurgent activity. Since the uprisings began, communication with much of Segmentum Pacificus has been lost.
In M42, Segmentum Pacificus faced an unprecedented threat when the Tyranid Hive Fleet Leviathan launched a massive new offensive into the region. The Imperium found itself initially unprepared, and Imperial heroes such as Lord Commander Solar Arcadian Leontus and Captain-General Trajann Valoris are rallying forces around Sanctum to resist the xenos tide.
- Adrantis Five
- Mortikah VII
- Nova Terra
- Ultima Macharia
Notable Other Celestial Objects
Notable Sectors and Sub-Sectors
- Segmentum Solar - Galactic East
- Segmentum Obscurus - Galactic North East
- Ultima Segmentum - Galactic Far East
- Segmentum Tempestus - Galactic South East
- 1: Rogue Trader Rulebook
- 2: Warhammer 40,000 6th Edition Rulebook, pg. 177
- 3: Warhammer 40,000 5th Edition Rulebook, pgs. 124-125
- 4: Codex: Imperial Guard (5th Edition), pg. 13
- 5: Warhammer Quest: Blackstone Fortress Background Guide pg.5
- 6: Leviathan (Box) Rulebook, pg. 220-230