Thousand Sons - The Great Change, M30-M31: Unification Wars, Pacification of the Boetian Lowlands (ca. 798.M30) - When the XV Legion was created they were used to quell the few pockets of isolated resistance to the Emperor's rule that remained on Terra during the Wars of Unification. Boetia was a nation that had existed since the Age of Strife and was chiefly known for holding out against the Unification for a considerable period of time until it was finally forcibly incorporated in the newborn Imperium. The ruling family, the Yeselti, attempted to stubbornly cling to power, forcing Imperial Army forces to invade their province the Astartes of the XV Legion were sent in to finally crush any further resistance in a brilliant campaign that lasted only six weeks. Shortly after achieving this objective, the XV Legion was formally named the Thousand Sons by the Emperor Himself and was sent out into the galaxy as part of His Great Crusade. This particular conflict holds the distinction of being the final campaign of the Unification Wars that took place during the Great Crusade.Xenocide of Kamenka Troika (ca. 900s.M30) - This was a campaign of extermination waged in the middle years of the Great Crusade against the barbaric Greenskins (Orks) of the Kamenka Troika system. The Emperor had issued the writs of war, commanding the Thousand Sons, the Legio Astorum Titan Legion and a Lifehost of PanPac Eugenians of the Imperial Army to drive that savage race of xenos from the three satellite planets of Kamenka Ulizarna, a world claimed by the Mechanicum of Mars. The savagery of that war, the slaughter and relentless, grinding attrition had left tens of thousands of dead in its wake. The Imperial forces proved victorious after two standard years of fighting and earned a score of honours for their war banners. Victory had been won, but the cost had been high. The Thousand Sons sustained severe losses of 873 Battle-Brothers of the 5th Fellowship, effectively wiping the 5th out as a functioning unit. This forced Magnus the Red to reduce his Legion from ten Fellowships to the Pesedjet, the nine classic Fellowships of Prosperine antiquity.Aghoru Campaign (ca. 999.M30) - The world of Aghoru was the fifth planet in a system of otherwise dead worlds, discovered by the Thousand Sons' 28th Expeditionary Fleet at the height of the Great Crusade. This world soon proved to be home to an underdeveloped culture of human inhabitants, also known as the Aghoru, who possessed little to no knowledge of science. The Imperial Compliance of the world of Aghoru (officially codified in Imperial records as 28-16) was an action carried out by units of the Thousand Sons Legion that was achieved through diplomacy and was considered a success. Interestingly, the human population possessed ancient legends of a race of elder beings known as the "Elohim" (which might be analogous to the Eldar). According to their mythology, a perverted and corrupt daemonic force, known as the "Daiesthai", who had succumbed to the corruption of the Elohim's self-obsession, and hedonistic excesses, was imprisoned within the massive, artificially constructed peak, designated by the Thousand Sons as "The Mountain". This titanic peak was set in a salt plain at the edge of a valley and rose larger than the tallest peak of Olympus Mons on Mars. Surrounding the base of the Mountain were scattered circles of raised stones, designated as "deadstones", each rose taller than three men. These so-called "deadstones" served as a tool to blunt the psychic forces surrounding the artificial peak. The Thousand Sons Primarch Magnus was enthralled by the planet's mountain and the tomb of the dormant Daiesthai. Upon further investigation within the artificial mountain, Magnus discovered that it was some kind of gateway with a web-like network of conceptual conduits, containing billions of pathways between worlds. Unfortunately, Aghoru's link to the network had become corrupted by the warp and was ultimately sealed. During the Thousand Sons time on Aghoru, somehow Khalophis, a Captain of the Thousand Sons 6th Fellowship (Company), seemingly awoke the mysterious force when he struck the base of one of the mountain's guardian Titans (which resembled Eldar Titans, though this has not been implicitly confirmed). Roused from their millennia long slumber by the corrupt force of the Mountain, the valley's guardian Titans awoke and began to attack. The Titans were only defeated through the combined efforts of the Crimson King, his Thousand Sons and a contingent of Space Wolves, who had recently arrived to support the campaign in the Ark Reach Cluster. In the battle's aftermath, Magnus explained that these encountered warp denizens were in reality, daemons, one of the denizens of the "Great Ocean".Ark Reach Cluster (ca. 000.M31) - The Ark Reach Cluster had been discovered by the Word Bearers Legion's 47th Expeditionary Fleet; it was a group of binary stars occupied by a number of belligerent planetary empires that rejected the Imperium's offer to become part of the Emperor's growing demesne. This Imperial Compliance action of the Great Crusade was carried out through the combined efforts of the Thousand Sons working in concert with elements from the Space Wolves and the Word Bearers Legions. The first four star systems fell to the Word Bearers and Space Wolves. But the fifth and sixth world, known as Shrike, required the assistance of the Thousand Sons. The return to the XV Legion of the dreaded mutational Flesh-Change occurred at the conclusion of this campaign and helped to bring on the eternal enmity between the Space Wolves and the Thousand Sons whom their cousins regarded as "impure".Fall of Prospero (734.004.M31) - The Fall of Prospero was the name given by later Imperial scholars to the sanctioned Imperial military reprisal against the XV Legion's homeworld of Prospero at the start of the Horus Heresy in the early 31st Millennium. The Thousand Sons had looked too deeply into the tides of the daemonic warp when the Emperor Himself demanded the Thousand Sons stay blind, in accordance with His edicts laid down during the Council of Nikaea. And so, judgement fell upon the XV Legion. That judgement came in the form of the VI Legion -- also known as the Einherjar, the Vlka Fenryka, the Rout; and by their basely literal Low Gothic name, the Space Wolves. They were also accompanied by elements of of the Legio Custodes and the Sisters of Silence. The VI Legion descended upon Prospero, not on the Emperor's orders but those of Warmaster Horus. The Emperor had demanded the Thousand Sons be returned to Terra under shameful arrest. It was Horus, manipulating the tides of war before it was even truly declared, who arranged for the Thousand Sons' censure to become their execution. He wanted the XIV Legion to despise the Imperium. The Warmaster wanted them -- those who survived -- to stand with him against the Emperor when they had nowhere else to turn. And the Wolves obliged him. In their ignorance, as tragic as the Thousand Sons' own, they fell upon their cousin Legion. The Space Wolves' only sin was to be betrayed by those they trusted, for they had no reason to doubt the Warmaster's words. Later on, the newly-dubbed Black Legion would devise their own name for the Wolves -- Thulgarach, "the Deceived". The word itself places emphasis on the cunning of the deceiver, rather than the foolishness of the deceived. The destruction of Prospero would inevitably be Horus' triumph, not the Wolves'. Though the Thousand Sons' Primarch Magnus the Red was aware of the impending assault and the vulnerability of orbital attack, he chose not act, as he felt that his sins warranted the Emperor's sanctions against him. The Space Wolves viciously bombarded the surface of planet and then launched a massive orbital strike with devastating results, slaughtering all life on the surface of Prospero. The battle finally concluded with Magnus and Leman Russ facing one another in personal combat, which resulted in the Red Cyclops being cast down and his back broken. Seeing his imminent demise near at hand, Magnus cast a mighty spell that took the great city of Tizca, his remaining Astartes and what precious archives of forbidden lore they could save, to their new homeworld known as the Planet of the Sorcerers, prepared by their patron Chaos God Tzeentch somewhere within the Eye of Terror.The Rubric of Ahriman (Unknown Date.M31) - Ahriman and his cabal weave a great spell in an attempt to rid the Thousand Sons Legion of their harrowing mutations. When unleashed, this Rubric of Ahriman reduces the vast majority of the Thousand Sons to dust, and entombs what remains of their spirits within Warp-infused armour. Discovering what his most trusted son has wrought upon the Legion, Magnus becomes enraged, but Tzeentch intervenes and Magnus spares Ahriman's life, instead casting him out as an exile.First Battle of Garm (Unknown Date.M31) - In the aftermath of the Horus Heresy, the Thousand Sons attacked the Space Wolves' Shrine World of Garm, which was named for a famous Wolf Lord from the earliest days of the Space Wolves Legion who had given his life defending the Primarch Leman Russ from an attack by Magnus the Red. Leman Russ raised a cairn to Garm upon the place of his death and placed the Spear of Russ, the mighty weapon gifted to him by the Emperor Himself which had wounded the Traitor Magnus, atop Garm's tomb. The Space Wolves were able to fight off the Thousand Sons Traitor Legion and drive them from the world.