The Great Rift is a galaxy-spanning tear in reality that split the Imperium in half at the end of the 41st millennium. The Imperium calls it the Cicatrix Maledictum, and it’s the single biggest change to the Warhammer 40k setting since the Horus Heresy.
What the Great Rift actually is
It’s a chain of catastrophic Warp rifts running across much of the galaxy, not one clean cut but a sprawling wound in realspace. Warp travel and astropathic communication became nearly impossible across huge stretches of the Imperium, an event remembered as the Blackness.
Worlds were cut off, Chaos forces poured through, and the Imperium effectively split into two halves: Imperium Sanctus on one side and Imperium Nihilus on the other.
How it formed
The Rift opened at the close of the 41st millennium during Abaddon’s Thirteenth Black Crusade, right after Cadia fell. That much is agreed on. Almost everything else is argued about in-universe.
Theories include the destruction of the Cadian Pylons, sorcery by Magnus the Red during the Siege of the Fenris System, the awakening of Ynnead, mass bloodshed in the Damocles Gulf, and the Ruinous Powers reacting to Roboute Guilliman’s resurrection.
Guilliman himself suspects Abaddon spent ten thousand years methodically destroying worlds rich in blackstone, with Cadia as the final trigger. Nobody in the setting can prove it.
What it does to reality
The Rift doesn’t just separate places, it breaks the rules. Time itself frays. Some worlds have lived through centuries in an instant, others are frozen, and others shift back and forth without warning.
Stars have swollen red and grown tendrils of plasma that reach out to burn worlds, or been pulled bodily into the Warp. Void ships caught near the Rift have been boarded by things that slaughtered whole crews. Entire systems have simply vanished.
What different cultures call it
The Imperium’s name, Cicatrix Maledictum, isn’t the only one. Orks call it Gork’s Grin. The Asuryani call it the Dathedian. The T’au know it as the Greater Axial Rift, or Mont’yhe’va, the Devourer of Hope. Fenris and the Space Wolves call it Everdusk.
The variety matters. It shows the Rift isn’t just an Imperial disaster, it’s a galaxy-wide one that every faction has had to name and reckon with.
| Name | Used by |
|---|---|
| Cicatrix Maledictum | The Imperium |
| Gork’s Grin | Orks |
| Dathedian | Asuryani |
| Mont’yhe’va (Greater Axial Rift) | T’au |
| Everdusk | Fenris and Space Wolves |
Why it matters
The Great Rift is the reason the modern 40k setting looks the way it does. It turned the Imperium into two halves that can barely reach each other, pushed the Indomitus Crusade into motion, and gave Chaos a foothold across almost every front.
If you’re reading anything set after the 41st millennium, the Rift is the context behind it.
Key facts
- The Great Rift is a chain of Warp rifts that split the galaxy and the Imperium in two.
- It opened at the end of the 41st millennium, right after Cadia fell during the Thirteenth Black Crusade.
- The Imperium calls it the Cicatrix Maledictum; other factions have their own names for it.
- Warp travel and astropathic communication broke down across huge regions, an event called the Blackness.
- Its cause is officially unknown, with several competing theories in-universe.
- Time distortions, vanished systems, and mutated stars are all documented effects.
FAQ
What is the Cicatrix Maledictum?
It’s the Imperium’s name for the Great Rift, the galaxy-spanning Warp tear that opened after Cadia fell. Same thing, different name.
When did the Great Rift form?
At the very end of the 41st millennium, during Abaddon’s Thirteenth Black Crusade and immediately after the destruction of Cadia.
What caused the Great Rift?
In-universe sources disagree. Candidates include the loss of the Cadian Pylons, Magnus the Red’s sorcery, Ynnead’s awakening, and Abaddon’s long campaign against blackstone worlds. Guilliman favours the blackstone theory.
What is Imperium Nihilus?
It’s the half of the Imperium cut off on the far side of the Great Rift, where Warp travel and communication are hardest and Chaos has the strongest grip.