Neither side is winning decisively. The Great Rift split the Imperium in half, giving Chaos its greatest victory in ten millennia. But Roboute Guilliman’s return and the Indomitus Crusade have stabilised parts of the Imperium and pushed back on multiple fronts. The Warhammer 40,000 setting is deliberately kept in a perpetual stalemate — neither Chaos nor the Imperium can achieve final victory because that would end the story. What we have instead is a galaxy-spanning war of attrition where both sides trade devastating blows without landing a knockout punch.
What Is the Current State of the War?
The war between Chaos and the Imperium has raged for over 10,000 years, but the current era — the Era Indomitus — represents the most dramatic shift in the conflict since the Horus Heresy.
The pivotal event was the 13th Black Crusade, led by Abaddon the Despoiler. After twelve previous attempts that ended in apparent failure (though each actually achieved hidden strategic objectives), Abaddon finally succeeded in destroying Cadia — the fortress world that had guarded the Eye of Terror for millennia. Cadia’s fall unleashed the Great Rift (Cicatrix Maledictum), a galaxy-spanning tear in reality that split the Imperium in two.
The Great Rift runs from the Eye of Terror to the Eastern Fringe, creating a permanent Warp storm that divides the galaxy into Imperium Sanctus (the side with Terra, still receiving the Astronomican’s light) and Imperium Nihilus (the dark side, cut off from the Emperor’s beacon). Billions of Imperial citizens in the Nihilus are effectively abandoned — unable to receive reinforcements, supplies, or communication from Terra.
This was Chaos’s greatest strategic victory since the Horus Heresy. The Imperium lost not just a planet but its entire defensive strategy. The Cadian Gate was the keystone of ten thousand years of military planning, and its destruction fundamentally altered the balance of power.
How Has the Imperium Responded?
The Imperium’s response came in the form of two miracles: the return of Roboute Guilliman and the introduction of Primaris Space Marines.
Guilliman, Primarch of the Ultramarines and effectively the Imperium’s greatest military and administrative mind, was resurrected from mortal stasis through a combination of Aeldari intervention and the power of Belisarius Cawl’s technology. His return was the first time a loyalist Primarch had walked the galaxy in ten millennia, and his impact was immediate and massive.
Guilliman launched the Indomitus Crusade — the largest military campaign since the Great Crusade itself. Fleets of warships, armies of the reborn Primaris Space Marines, and vast formations of Astra Militarum forces pushed out from Terra to reclaim systems lost to Chaos, stabilise the border regions around the Great Rift, and re-establish communication with the Imperium Nihilus.
The Indomitus Crusade has achieved significant successes. Hundreds of worlds have been reclaimed or reinforced. New Primaris chapters have been founded to replace those destroyed during the 13th Black Crusade. Supply lines have been re-established across parts of the Rift using stable Warp routes and Necron Dolmen Gate technology (reluctantly shared). The Imperium is bloodied but fighting back.
Guilliman has also attempted administrative reform — an enormous challenge given the Imperium’s 10,000 years of institutional decay, bureaucratic ossification, and religious fanaticism. His relationship with the Ecclesiarchy, the Inquisition, and the Adeptus Mechanicus is strained at best, and his efforts to modernise the Imperium’s governance are met with suspicion and resistance from institutions that have spent millennia calcifying around the Emperor’s (possibly misinterpreted) will.
What Has Chaos Gained?
Chaos has made enormous gains in the current era, even if it hasn’t achieved outright victory.
The Great Rift itself is a permanent gain. It’s not a temporary Warp storm that will dissipate — it’s a fundamental change to the galaxy’s metaphysical geography. Daemonic incursions are now easier across the entire galaxy, Warp travel is more dangerous than ever, and the barrier between the material universe and the Immaterium is thinner everywhere.
Abaddon has consolidated his position as Warmaster of Chaos, commanding a level of authority over the traitor Legions that hasn’t been seen since Horus himself. The formation of Vashtorr’s alliance and the ongoing hunt for the Dark Pact’s ultimate weapons have given Chaos new strategic assets. Individual Chaos champions — Mortarion, Magnus, and others — have carved out their own daemon worlds and power bases in the Rift’s shadow.
The Imperium Nihilus is effectively a Chaos playground. Without the Astronomican’s light to guide Warp travel, and with limited Imperial Navy presence, the worlds of the dark Imperium are vulnerable to raiding, corruption, and outright invasion. Some have fallen to Chaos entirely. Others cling to survival through sheer stubbornness and the heroism of local defenders — isolated Space Marine chapters, remnant Astra Militarum regiments, and desperate planetary defence forces.
Chaos also benefits from a subtle advantage: time. The Imperium is a declining civilisation. Its technology base is shrinking (despite Cawl’s efforts), its population is burdened by endless war, and its institutions are riddled with corruption, both mundane and supernatural. Every century that passes sees the Imperium weaker and more fragile. Chaos, fuelled by emotion and conflict, only grows stronger as the galaxy spirals further into war.
Why Can Neither Side Win?
The Chaos-Imperium conflict is designed as a narrative stalemate, and both sides have structural limitations that prevent decisive victory.
Why Chaos can’t win outright: The Chaos Gods are fundamentally incapable of true cooperation. Khorne, Tzeentch, Nurgle, and Slaanesh each pursue their own agenda and actively undermine each other. A unified Chaos assault would overwhelm the Imperium — but unity is antithetical to Chaos’s nature. Every time Chaos achieves a major victory, the Dark Gods fall to infighting over the spoils. Abaddon is the only figure who has ever managed to direct all four powers toward a single objective, and even his control is temporary and fragile.
Additionally, Chaos needs the Imperium. The emotions of trillions of suffering, fighting, fearing humans are what feed the Chaos Gods. If the Imperium were destroyed, the Chaos Gods would lose their primary source of sustenance. They don’t want to win — they want the war to continue forever, generating endless suffering and devotion. This is the great irony of the 40k setting: Chaos fights the Imperium but needs it to survive.
Why the Imperium can’t win outright: The Imperium cannot destroy Chaos because Chaos is a fundamental aspect of the Warp, which is in turn a reflection of mortal emotions. As long as sentient beings feel anger, ambition, despair, and desire, the Chaos Gods will exist. The Imperium could theoretically seal the Warp rifts and contain daemonic incursions, but it cannot destroy Chaos itself without fundamentally altering the nature of reality.
The Emperor understood this, which is why his original plan (the Imperial Webway Project) focused on severing humanity’s dependence on the Warp rather than defeating Chaos directly. That plan was destroyed during the Horus Heresy, and no alternative has been developed in the ten millennia since. The Imperium is fighting a holding action against an enemy that cannot be permanently defeated — and it’s losing ground, slowly, century by century.
What Are the Key Battlefronts?
The war between Chaos and the Imperium spans the entire galaxy, but several key theatres define the current conflict:
- The Great Rift border: The zones where the Rift meets realspace are constant warzones. Imperial forces maintain defensive cordons while Chaos warbands and daemonic incursions probe for weaknesses. This is where most of the “conventional” fighting occurs.
- Imperium Nihilus: The dark half of the Imperium is a desperate battleground where isolated Imperial forces fight for survival against Chaos, xenos, and despair. The Blood Angels and their successors, under Commander Dante, are the primary Imperial authority in the Nihilus.
- Vigilus: This strategically vital world controls one of the few stable passages across the Great Rift. Control of Vigilus means controlling access between Imperium Sanctus and Nihilus. It has been the site of massive campaigns involving Abaddon’s forces and Imperial defenders.
- The Plague Wars: Mortarion’s Death Guard launched a massive invasion of Ultramar, Guilliman’s home territory. The resulting Plague Wars were a major narrative campaign that saw Guilliman defend his realm against daemonic and traitor forces.
- The Arks of Omen: Abaddon’s campaign to locate and weaponise ancient artefacts has sent his forces across the galaxy, striking at targets of strategic and metaphysical importance.
What Does the Future Hold?
Games Workshop has been advancing the 40k narrative more aggressively in recent years, but the fundamental dynamic is unlikely to change. The setting’s appeal depends on the tension between hope and despair — the Imperium strong enough to survive but not to triumph, Chaos powerful enough to threaten but not to conquer.
Potential narrative developments include the return of more Primarchs (both loyalist and traitor), the resolution of the Emperor’s fate on the Golden Throne, the development of Ynnead as a potential counter to Chaos, and the continued evolution of the Primaris Space Marines. Each of these could shift the balance temporarily, but the stalemate will persist because it’s the foundation of the setting.
For players and lore fans, the current era is arguably the most exciting time in 40k history. The narrative is actually moving forward — characters develop, empires shift, and the status quo is challenged. The war between Chaos and the Imperium may never end, but it’s never been more interesting to follow.
Frequently Asked Questions
Did Chaos win the 13th Black Crusade?
Yes, the 13th Black Crusade was a decisive Chaos victory. Cadia was destroyed, the Great Rift was opened, and the Imperium was split in half. This represented the greatest Chaos achievement since the Horus Heresy. However, Abaddon failed to reach Terra or destroy the Imperium entirely, and Guilliman’s return has partially reversed the gains.
Is the Emperor dying?
The Emperor has been interred on the Golden Throne for over 10,000 years, sustained by the daily sacrifice of thousands of psykers. His physical body is essentially a corpse, but his psychic power remains immense — he powers the Astronomican and holds shut the Warp breach beneath the Imperial Palace. Whether he is “dying” in any meaningful sense, or whether his current state is part of a larger plan, is one of 40k’s greatest mysteries.
Could the Imperium and Chaos ever ally?
Never officially, but in practice, individual Imperial and Chaos forces have cooperated against mutual threats — particularly Tyranids and Necrons. These alliances are always temporary, unofficial, and deeply heretical. Any Imperial commander caught cooperating with Chaos would face immediate execution by the Inquisition, regardless of the circumstances.
What would happen if the Emperor died?
This is the Imperium’s ultimate nightmare scenario. Without the Emperor powering the Astronomican, Warp travel would become nearly impossible, isolating every world in the Imperium. Without him holding shut the Warp breach under Terra, the Throneworld itself could become a daemon world. Some believe his death would birth a new Chaos God; others think he would be reborn. Games Workshop has kept this deliberately ambiguous.
Is Guilliman strong enough to save the Imperium?
Guilliman is a Primarch — one of the most powerful beings in the galaxy — but he’s fighting an institution as much as an enemy. The Imperium’s problems are systemic: corruption, religious fanaticism, technological stagnation, and ten thousand years of accumulated dysfunction. Guilliman can win battles and even campaigns, but transforming the Imperium into something capable of ultimate victory is a challenge that may exceed even a Primarch’s capabilities. His own frustration with this reality is a major theme in the current lore.
Have any other Primarchs returned besides Guilliman?
Yes. Lion El’Jonson, Primarch of the Dark Angels, has returned in current lore and is fighting for the Imperium again. On the traitor side, several Daemon Primarchs have come back to realspace in force: Magnus attacked Fenris, Mortarion led the Plague Wars against Ultramar, and Angron has manifested again at the head of the World Eaters.