It is said by ancient proverb that truth is the first casualty of war and, if this is the case, then rumour is its first child. Almost from the outset, the war of the Horus Heresy was a vast cataclysm, one whose events moved with such quicksilver pace that mystery, supposition, lies and simple ignorance cloaked much of the bloodshed even as it occurred, casting a veil over much that will never be lifted. Though the roll call of Space Marine Legions, Titan Legions, Auxilia regiments and Mechanicum Taghmata that sided with the Arch-Traitor Horus and those who remained loyal is largely known and accepted, the full truth is far more complex and far more mysterious than commonly believed. Some Legiones Astartes believed Horus had the superior cause and the superior right to command their allegi