Timeline of the Warhammer 40,000 Universe - The Waning (ca. M38 - ca. 750.M41): With the Imperium's military forces in every branch utterly exhausted by the Redemption Crusades, star system after star system fell to Ork invasion, Chaos insurgence or sheer rebellion. 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.Having purged more than 400 worlds within the Eye of Terror, the survivors of the Abyssal Crusade returned to Imperial space in 112.M38. Without pausing to claim the honours due for such a successful and protracted Imperial Crusade, Chapter Master Konvak Lann of the Vorpal Swords declares the now ancient Saint Basillius a false idol and adoration of him tantamount to betrayal. In less than a standard year, every known sepulchre and shrine dedicated to the false saint is destroyed. After his execution, his bones, along with countless relics, books of doctrine and thousands of living worshippers, are placed on a derelict bulk-freighter and launched directly into a nearby star.During the Grim Harvest in 666.M38, a great armada of misshapen space hulks drifts out of the Warp near Terra. Some of the twisted and fused starships can still be identified as transports carrying pilgrims from the Lost Crusade. The Inquisition works feverishly to cover up the fleet's existence and its cargo of mutant and Daemon-possessed abominations.In 001.M39 the Conflict of Helica unfolded.In 103.M39 the Mausolean Cataclysm struck the Imperium.In 131.M39, the Redemption Crusades begin. In each of the segmentae of the Imperium a great hero emerges. Like unto the primarchs of old are these warriors, and the combined efforts of their 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 vanish without a trace, spurring Ecclesiarch Inovian III to declare them Imperial saints returned to the Emperor's side.A Black Crusade is the term used to describe a number of mass incursions by Chaos Space Marines and the other forces of Chaos into Imperial space from the Eye of Terror. The most prominent of these are the Black Crusades led by the Black Legion's Warmaster of Chaos and Horus' successor as the greatest Champion of Chaos Undivided, Abaddon the Despoiler. 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.The Gothic War 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 in the conflict, along with every naval vessel the Battlefleet Obscurus can 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, which would return a thousand standard years later to plague the Imperium at its darkest hour.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.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, barbaric 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 eye sockets. Although the dreams take myriad forms, all know that the Emperor weeps not for Himself, but for the darkening plight of Humanity.