The Horus Heresy began not with a battle but with a betrayal so vast it split the Imperium in two. Horus Lupercal, beloved Warmaster and favoured son, was corrupted upon the moon of Davin and turned his allegiance to the Ruinous Powers. When he raised his banner, half the Space Marines of the Legiones Astartes marched with him, and the galaxy that the Emperor had spent two centuries uniting began to burn.
From the massacres of the Isstvan system to the final agony beneath the walls of the Imperial Palace, the war consumed worlds without number. Brother slew brother; primarchs fell to primarchs; entire cultures were rendered to ash in reprisal and counter-reprisal. The Chaos Space Marines were born in this fire, their oaths to humanity traded for the whispered promises of daemons.
Though the Emperor cast down Horus in the end, the victory was hollow. Interred within the Golden Throne, more machine than man, He could no longer lead the realm He had forged. The surviving Traitors fled into the Eye of Terror, there to nurse ten thousand years of hatred. The Heresy did not simply wound the Imperium; it defined every grim century that followed, casting its shadow across all of the age of darkness to come.
The chronicle continues
