Sons of Horus
The Sons of Horus, originally known as the Luna Wolves, were the XVI Legion of the original twenty Space Marine Legions. Their Primarch was Horus, known to them as Horus Lupercal, and to Imperial history as the instigator of the Horus Heresy, the first great Imperial civil war. The majority of the Sons of Horus had no hesitation to renounce their oaths to the Emperor following their Gene-father Horus into battle. The portion of the Legion that stayed loyal to the Emperor was betrayed and wiped out by their brothers on the world of Isstvan III.