The Waning

The Waning was a relatively undefined era of the Age of the Imperium that lasted from early in the 38th Millennium until ca. 744.M41.

It was characterised by a slow degradation of the Imperium's stability, power and peace as new Chaos and xenos threats assaulted the Emperor's worlds.

With the Imperium's military forces in every branch utterly exhausted by the continuous Imperial Crusades of the prior Age of Redemption, star system after star system fell to Ork invasion, Chaos insurgence, xenos infestation or sheer rebellion.

It came to an end with the start of the greatest period of turmoil and strife in Imperial history since the Horus Heresy, known as the Time of Ending.

Notable Events

Anarchy throughout many sectors of the Imperium was rife during a dark period in Imperial history that is now called "the Waning."

Ever more star systems were turned over by the Administratum to direct rule by Space Marine Chapters to preserve stability as only the Astartes possessed the inviolable military strength required to restore Imperial control in the more lawless regions of the galaxy.

To combat the spreading anarchy, the Adeptus Terra imposed ever-stricter rules, doling out ever-harsher punishments. Portents of doom were both incessant and relentless. The prescient foretold of great ripples in the Warp, like a swell in the water disturbed by some colossal but unseen menace.

9th Black Crusade

The 9th Black Crusade of Abaddon the Despoiler and his Black Legion launched out of the Eye of Terror in 537.M38. Intending to bring about the demise of the naval fortress of Cancephalus, Abaddon led his forces against the heaving populations of the nearby world of Antecanis.

The seventeen-standard-year-long war that ensued robbed both Antecanis and Cancephalus of their most precious resource -- manpower. Without the fleets of Cancephalus to stop him, Abaddon was able to ravage the rest of the sector at will , and his Sorcerers were free to conduct the rituals required to weaken the walls of reality in that region of space with impunity.

Grim Harvest

During the "Grim Harvest" in 666.M38, a great armada of misshapen space hulks drifted out of the Warp near Terra. Some of the twisted and fused starships could still be identified as transports carrying pilgrims from the Lost Crusade.

The Lost Crusade had begun in 754.M37, when, on thousands of planets, menials rebelled against their dreary drudgery with wild-eyed leaders espousing a better way of life -- a galaxy of tolerance. The movement had been especially popular amongst the youth of the Imperium, earning it the title of "Children's Crusade."

Billions of earnest pilgrims were lured to seek transport to Terra; some were waylaid by pirates, but the majority disappeared into the Warp. They became known collectively as the "Lost Crusade."

The Inquisition worked feverishly to cover up the Grim Harvest fleet's existence and its cargo of mutant and daemon-possessed abominations.

10th Black Crusade

The 10th Black Crusade, also known as the "Conflict of Helica," was a joint campaign of the forces of Chaos that was led by Abaddon the Despoiler and the Daemon Primarch Perturabo of the Iron Warriors Traitor Legion. Launched out of the Eye of Terror in 001.M39, both the Black Legion and the Iron Warriors struck against the Helica Sector.

While the Black Legion attacked the capital world of the sector, the Hive World of Thracian Primaris, the Iron Warriors focused their own assault against Medusa, the homeworld of the Loyalist Iron Hands Chapter, to fulfil an old blood debt. In a series of bitter sieges, the Iron Warriors assaulted the Medusa System's worlds and pushed the Iron Hands to the brink of destruction.

Only when the Loyalist Chapter received heavy Imperial reinforcements did Abaddon and the Iron Warriors retreat back to the Eye of Terror, taking with them valuable information about the world of Medusa and its defences to be used at a later and more opportune time.

Mausolean Cataclysm

In 103.M39 the Mausolean Cataclysm struck the Imperium.

Redemption Crusades

In 131.M39, the so-called "Redemption Crusades" began. In each of the segmentums of the Imperium a great hero emerged. Like unto the Primarchs of old were these warriors, and the combined efforts of their Imperial Crusades push back the borders of the Imperium further than they have been for nearly 500 standard years.

And then, 50 Terran years later, the five heroes vanished without a trace, spurring Ecclesiarch Inovian III to declare them Imperial Saints returned to the Emperor's side.

11th Black Crusade

In 301.M39, Abaddon the Despoiler launched his 11th Black Crusade, also remembered as the "Doom of Relorria," out of the Eye of Terror. In an attempt to break through the cordon of Warp Storms surrounding the Eye into Imperial space, he employed a captured daemon to navigate for his Black Fleet.

The effort proved fruitless, and instead the daemon warped the Black Legion's Black Fleet directly into the path of the Orks of WAAAGH! Murgor. In the ruins of the Cardinal World of Relorria, the Black Legion brought the Orks to battle, Bolter rounds and Chainswords tearing into the green-skinned xenos.

After solar months of bloody warfare, Abaddon decided to leave Relorria to its fate and the Black Legion returned to the nightmare realm of the Eye of Terror -- but not before the Warmaster of Chaos filled the holds of his Black Fleet with a multitude of captured Ork Weirdboyz.

In conjunction with a coven of his most powerful Sorcerers, he used the volatile psychic energies of the Greenskin abductees in a daemonic hybridisation ritual that weakened the fabric of reality across the Relorrian System, part of a wider plan to find ways to break down the barriers between the Immaterium and realspace and so aid Chaos' assault on the Imperium.

Gothic War (12th Black Crusade)

In 139.M41, the 12th Black Crusade, better known as the "Gothic War," was a vast campaign launched by Abaddon that engulfed the Gothic Sector of the Segmentum Obscurus after that sector was cut off from Imperial reinforcements and communications by a series of massive Warp Storms produced by the will of the Ruinous Powers.

It consisted of hundreds of planetary invasions and naval battles spanning the time period 139.M41 - 160.M41 and only ended when Abaddon and his Chaos Space Marines, Renegade Chapters, daemonic hosts and rebellious Chaos Cults were forced to retreat into the Immaterium with the arrival of Imperial reinforcements as the Warp Storms that had provided cover for their invasion finally dissipated just as mysteriously as they had begun.

On the Imperial side, dozens of Space Marine Chapters, nearly 100 Astra Militarum regiments and the better part of three Titan Legions took part, along with every naval vessel the Battlefleet Obscurus could muster.

The conflict saw the destruction of several planets and four of the six irreplaceable ancient alien artefacts known as the Blackstone Fortresses as well as the deaths of millions, if not billions, of Imperial citizens.

Most significantly, the events of the Gothic War revealed the true nature and purpose of the ancient spaceborne alien artefacts known to the Imperium as the Blackstone Fortresses, which had been created by the Old Ones to be used against the Necrons and were capable of destabilising stars and destroying entire solar systems.

Most importantly, Abaddon and the forces of Chaos were able to escape back into the Eye of Terror with two of the Blackstone Fortresses, their future purpose unknown.

Macharian Crusade and Heresy

This period saw the Macharian Conquests (also called the Macharian Crusade) of 392-399.M41 during which Lord Commander Solar Macharius, the Lord of the Segmentum Solar, mustered the greatest human army the galaxy had seen since the Great Crusade.

In only seven standard years, Macharius reconquered a thousand worlds on the western reaches of the Imperium and his glory carried him into the darkest sectors, places where the Emperor's light had never been known.

Upon his death, the whole Imperium wept for the lost commander, but Macharius' conquered territories soon collapsed into rivalry and civil war. The Macharian Heresy, as this time is now known, lasted for seventy standard years and was only ended through the combined efforts of one hundred Space Marine Chapters.

Tears of the Emperor

In 500.M41, in an event known as the Tears of the Emperor, the Imperium was swept by visions of the Emperor's tears.

From backwards Feral Worlds to the most densely populated Hive Worlds, a million versions of the same story are told by holy men, street agitators, shamans, priests, and mystics. Primitives point to storm-filled skies, claiming that the drops falling from them are the tears of their mighty god.

Upon Ecclesiarchy Cardinal Worlds, Arch-Deacons to lowly pilgrims claim to have seen statues of the divine Emperor shed tears. Chapter Masters and hive city urchins alike have visions of the Emperor stirring upon His throne, tears running from His empty sockets.

Although the dreams take myriad forms, all know that the Emperor weeps not for Himself, but for the plight of Humanity.

Sources

• Black Legion: A Codex Chaos Space Marines Supplement (6th Edition) (Digital Edition), pp. 37, 39-40
• Warhammer 40,000: Rulebook (8th Edition), pp. 40-47, 50-53, 123, 134, 152, 164-166
• Warhammer 40,000: Rulebook (6th Edition), pp. 168-177
• Warhammer 40,000: Rulebook (5th Edition), pp. 122-129