The Horus Heresy

The Horus Heresy is a significant fictional event in the Warhammer 40,000 universe, set in a distant future where humanity is at war with alien races and supernatural entities. It revolves around Horus, a favored general of the Emperor of Mankind, who is corrupted by chaos and leads a rebellion against the Emperor. This tragic conflict results in a galaxy-wide civil war, pitting loyalists against traitors. The Heresy shapes the future of human civilization, leading to the decline of the Imperium and the establishment of deep, enduring rivalries and themes of loyalty, betrayal, and sacrifice within the lore.