Thread is about loyalists who turned traitor in the 41st millennium, specifically loyalists from marine chapters who recently left their chapters. mine would have to be: Ardaric Vaanes (ex-Raven Guard), Svane Vulfbad (ex-Space Wolf), etc.
That's a tough one. I actually can't think of any who turned in the 41st millennium. The only instances in 41st I can recollect is when a chaos marine betrayed his legion and joined another. I wont say who though as one is a spoiler.
Soul Drinkers? OF ALL 40k I would have to say Alpha Legion. They had a very interesting reason for joining Horus, one that made me love them all the more (guess what legion im voting for to be the 5th).
Once a Shadow Captain of the Raven Guard's 4th Company, and a senior training instructor at the Ravenspire, for unknown reasons, Vaanes turned his back on his chapter and followed the path of other renegade Space Marines. He was declared Excommunicate Mortis in 934.M41. At some point in his travels, he joined the Red Corsairs under Huron Blackheart, but later left Huron's warband and swore allegiance to The "Dark Prince." He appeared as the leader of a ragtag group of other renegades surviving on Medrengard, home planet of the Iron Warriors inside the Eye of Terror. There he encountered Uriel Ventris and Pasanius Lysane, two Ultramarines who had been carried to Medrengard after being exiled from their chapter on a Death Oath. Uriel offered Vaanes and his men a chance for escape, and, more importantly, a chance to regain their honour, if they would help destroy Warsmith Honsou's fortress of Khalan-Ghol. Midway through the mission, Vaanes recanted and abandoned Uriel and Pasanius, outraged that their actions had caused the death of most of his men. He only narrowly survived the fortress's destruction, and was found wandering the rubble by Honsou and the remains of his Grand Company. Instead of killing him, Honsou offered the former Raven Guard a place at his side. Feeling he had been fooled and cheated by Ventris, Vaanes accepted. Vaanes was assigned to train The Newborn, a mutated clone of Ventris that Honsou had salvaged from the fortress, in unarmed combat. He participated in several of Honsou's subsequent actions, including the Skull Harvest on New Badab[2], the destruction of Tarsis Ultra, and the campaign to capture the Ultramarines' star fort Indomitable.[4b]
As far as entire chapters turning there's also Skyrar's Dark Wolves and the Crimson Slaughter. I can't pick a favorite as I haven't read Soul Drinkers and I dont want to read the lore and spoil the books. I do find the Soul Drinkers the most interesting however, just by being renegade marines who are still faithful to the Imperium. The Crimson Slaughter doesn't seem all that special in my opinion. The only only good they brought was the new models for TT. Oh, forgot the Red Corsairs. Still can't pick a favorite but the Red Corsairs are at the bottom of my list.
The results of the Abyssal Crusade continue to amuse me. Though the "400 worlds purged" thing is a bit much. All good stories deserve and even need a little embellishment, but 400 worlds is a bit much for a single Chapter to accomplish, when entire crusades involving the Navy, the Gaurd, and multiple companies and sometimes entire Chapters of Loyalist Astartes take years to retake a single system all while enjoying logistical support and suffering sometimes staggering losses. And despite having been "purged", those 400 worlds will, with absolute certainty, fall back into control of Daemons and Chaos Warbands as soon as the attacking force had departed for another world. So in the end, nothing was accomplished.
