I've enjoyed perusing this forum for many years, though only recently joined as a member. I have been working on a Death Guard heresy army, which has been a thoroughly enjoyable experience, for several years and I figured I should finally post it. The army is definitely still a WIP but I have a large amount of it that is mostly complete so far so I'll have quite a backlog of finished stuff already. Basing a large portion of the army is still on the list of things to do for sure.
I'm a huge fan of the background and lore, as well as of Your Dudes, hence I thoroughly enjoy creating conversions and kitbashes so you can see them along with some of the homebrew lore to support. I don't profess to be an amazing painter, though I'd say my skill has improved somewhat since this army was started. Being a gritty, dirty legion certain helps because you don't have to be super neat all the time.
Regarding the backstory for my Death Guard, I certainly am a loyalist at heart despite a traitor legion being my favorite, though I have to profess that "lost in the warp" is kinda of an overused trope so coming up with an alternative has been quite the challenge in my mind. I like to think that while humans are prone to blind loyalty and hence why the Death Guard follow Mortarion, it is fact that humans have free will and can be more complex than automatons that make for an interesting story, so failing due to human nature, eventually recognizing failure, and the quest for redemption is certainly appealing to me. I'd like to think they fought on both sides of the conflict at different points in time in the Heresy so I have an excuse to play the army as either side. First as traitors, then later as loyalists or at least tangentially aligned to the loyalist cause as blackshields.
The Harbingers of Extinction
Even amongst a legion which showed little restraint in the usage of weapons of dread reputation, those companies almost exclusively tasked with eradication of the most tenacious of xenos organisms stood above all others in the XIVth legion in their efficiency in such ways of destruction. Founded in the darkest days of the first Rangdan War, these companies were scraped together from the most hardened survivors of these conflicts. Bearing the scars of horrific physical and psychological mutilation, the few to retain their sanity at least partially intact would go on to form the basis of the newly constituted "harbinger" battalions; the proverbial bearers of a species’ last rites.
At the basis of these battalions was an operational doctrine patterned after the Dreadwing formations of the 1st legion whom they had often served alongside of during the first and subsequent Rangdan wars. These battalions usually consisted variably of 4 to 7 companies depending upon fighting strength and casualties suffered over the course of their campaigns. Equipped with esoteric wargear and the executors of tactics not often employed by the XIVth at large, these battalions quickly developed a reputation as exemplary eradicators of some of the most deadly and tenacious xenos species yet encountered by the Crusade fleets. At the height of the Great Crusade, there existed at least one Harbinger battalion within each of the Death Guard's great companies, though the unsustainability high attrition rate of men and irreplaceable war material would see this dwindle to just three immediately prior to the outbreak of the Heresy. The replacement and reconstitution of such specialized forces was indeed a goal of Mortarion near the end of the Crusade, though the lack of sufficient stock in the required resources prevented this from occurring, a fact endemic of how thin the legions were stretched in the latter years of the Great Crusade.
While diminished, the remaining Harbinger Battalions continued to maintain a hold on many examples of irreplaceable archeotech and rare prototypes only sparingly seen elsewhere in the Legiones Astartes. Perhaps the deadliest legacy of these formations was the extremely high concentration of exterminatus-class weapon systems for a force of this size, such that the extermination of all life within an entire subsector would be but a fraction of their full capabilities. Even still, sealed records of forgotten campaigns show that the deployment of such weapons of mass destruction by the harbinger battalions was not a rare occurrence. In fact, such devices were often used as an opening salvo to soften up their intended quarry, prior to the commitment of ground forces to eradicate species considered too dangerous for mere planetary containment alone. The fact that many habitable worlds were left toxic, radioactive, and/or psy-unstable wastelands in their wake was considered but a minor price for the Imperium to pay compared to the alternative.
Regarding the 47th Battalion of the 4th Great Company of the Death Guard Legion, known also by the moniker as the Harvesters of Worlds, it held both the reputation as the second oldest of the harbinger battalions and one of the last three still in existence prior to the Horus Heresy, having accumulated numerous commendations from its many campaigns. At the close of the 31st millennium, the 47th was almost entirely of Barbarus stock, resolute in both its loyalty to their primarch for liberating them from the monstrous Overlords, and of their resulting utter hatred of non-human life. Often deployed on extended missions to distant warzones, over its many decades of existence the 47th had grown to be a fairly insular group of warriors with a unique, but intensely grim culture by the standards of outside observers. Perhaps it was the mental scars of their experiences, or the nihilistic acceptance of a probable early demise, the warriors of the 47th were an exceptionally reserved group. They paid little heed to those accolades bestowed upon them by other members of the legion who knew little of what the 47th had wrought. Such trivialities were meaningless to warriors who steeped so heavily in the calculus of death.