Presented below is the Horus Heresy Chronology, an exhaustive listing of all known campaigns and battles that occurred during the galaxy-wide conflict known as the Horus Heresy in the early 31st Millennium. By no means is this list complete, as much of the information presented in various canon sources is often ambiguous and even, at times, contradictory. Therefore, this is merely a rough guide to the chronological order of the events, as they occurred, during this conflict.