Emperor of Mankind - Unification Wars: The man who would later become known as the Emperor of Mankind first appears in Imperial records as just one of the many warlords struggling for control of Terra during the later part of the Age of Strife in the early 29th Millennium.Beginning at that time, and with the aid of his great friend and collaborator Malcador the Sigillite, the Emperor undertook a series of military campaigns against all the other techno-barbarian warlords on the planet that would collectively later become known as the "Unification Wars."During these conflicts the Emperor employed several military formations -- such as the warriors of the unit designated Geno 5-2 Chiliad who would go on to serve in the Imperial Army -- that consisted of genetically-enhanced warriors to maximise His tactical prowess. The most powerful of these troops were the proto-Astartes known as the Thunder Warriors.Though physically the most potent of His creations, more deadly in combat than even the later Space Marines, the Thunder Warriors were far from perfect. Having been created from adult troops who had undergone a rapid process of genetic, bionic and chemical augmentation, many did have difficulty coping with the physiological changes. Metabolic collapse leading to rapid death was not uncommon, and many Thunder Warriors were also prone to mental instability and even psychosis as they aged.These warriors played a significant role in the Emperor's eventual victory over all the other warlords of Terra and led Him to believe that His future plans to reunite Mankind across the galaxy would require the creation of an even more potent core of genetically-engineered military commanders and warriors.Following the Battle of Mount Ararat in the Kingdom of Urartu, which was said in some sources to be the last battle of the Unification Wars, the Unity of Old Earth was at last achieved after standard centuries of blood, loss and fire. With this victory, the planet and population of Terra were at last unified under the single rule of the Emperor. But to make His dream of reuniting all of Humanity within a single galaxy-spanning empire possible, the Emperor knew that He would have to make some difficult, even immoral decisions.Their purpose having been achieved, the Emperor ordered all of the remaining Thunder Warriors to be liquidated. Their imperfections and propensity for mental decay rendered them a dangerous group of warriors to leave alive in a time of peace. They needed to be removed to make way for their eventual successors, the primarchs and the Space Marines.In truth, the Emperor was right to be worried about His creations. Another source claims that even before the Unification Wars had ended, the Thunder Warriors at last realised that their creator had cursed them with short lifespans as a result of their imperfect genetic augmentations, and turned upon Him for what they saw as His betrayal.It was a cadre of several hundred Custodians, even then believed to have been commanded by the legendary Constantin Valdor, and accompanied by several thousand prototype Astartes of the I Legion of the newborn Space Marines, that stood in the Emperor's defence, carrying out a merciless culling of the obsolete and rebellious gene-soldiers.Though some Thunder Warriors successfully escaped the cull, however it happened, the vast majority of those who survived the Unification Wars died at the hands of their own allies.Individually or in small groups -- like the self-stylised "Dait'Tar" Thunder Warriors present during the Cerberus Insurrection of the early Great Crusade era -- some Thunder Warriors would survive, living mostly anonymous and miserable lives amongst the population of Terra, all honours of the past forsaken, always fearful of being discovered.Fortunately for these survivors, the Imperium, believing them all dead, never truly sought to hunt them down, as all efforts were by now concentrated on the progress of the Great Crusade.Official Imperial propaganda proclaimed that the Thunder Warriors had heroically died to the last man during the Battle of Mount Ararat, the greatest of their number, Arik Taranis, surviving just long enough to raise the Emperor's banner when victory, and unity, was achieved.But the Emperor could not wipe away the stain entirely, for several Thunder Warriors managed to escape what they called "the Culling," including Arik Taranis, who would yet have a role to play in the fate of the Emperor's realm.With the Unification of Terra achieved, the Emperor next set in motion His plan to defend and better Humanity across the galaxy, by unifying those lost bastions of Mankind scattered across the myriad stars under the aegis of the newborn Imperium. This extraordinary undertaking would become known as the Great Crusade.