With the Imperium spreading through the galaxy, and burrowing into other realities. The Imperium had encountered nothing it could not handle with it's standard military might, Dire machines and their hybrid 'morph offspring provided a unique advantage for the Imperium in military situations, as well as the Imperium's sheer military might of their basic troops. For a while this was deemed enough, specialized units were trained and geared appropriately and while exemplary troops rose in the ranks but the need for teams of exceptional caliber and skill, what they needed were weapons, not soldiers.

The idea of mechanized war machines was quickly thrown out the window, they already had robotic drones fighting along side their troops, attempting to create AI dedicated to war was promptly viewed as a "bad idea" and taken off the table. No amount of safeguards could prevent a digital lifeform from becoming vastly more problematic. So they settled on fine tuning the best machine they knew of, People.

They went to those already in the Imperial Military for the initial test subjects, trying to convert already trained soldiers into something better. 30% suffered rejection of cybernetic implants, another 25% came into complications with the genetic modifications, the surviving 45% were only mildly successful, augmentations were minor, psychological problems sprung up in roughly 15% of them as well, leaving only a 30% mild success rate.

The successful ones of the initial "Super Soldier" program were not matching up to projected expectations, along side the complications and loss of life it was deemed not viable. Upon deeper inspection of the process a realization occurred, the subjects were too old. That is what was causing the difficulties with the augmentations, and there was no way to get the desired results and reduce loss of life, so they moved on to those that would be better candidates, children.

Genetic modifications could be administered over years in a growing child, allowing them to naturally adapt to the modifications, as well as with cybernetic augmentations. Raising said children as soldiers will make them psychologically capable of handling their power as well.

So the Imperium proceeded to search through for applicable children, those that show first and foremost a desire to help the Imperium at large, durable, athleticism, intelligence, and signs of emotional stability. Considering the Imperial education system is great at tending to intelligence and emotional stability it's rather common, finding those that matched most of the desired marks was easy, finding those whom at this age were willing to give themselves to the Imperial Military was rare.

Still, they came out with a little more than a hundred volunteers. The non humans with longer life spans were the first to undergo genetic modifications, bringing their growth rate in line with everyone else. Then over the next decade the children were raised into soldiers, into weapons.

At the end of the creation process the loss of life was the same as the prototypes, how ever they were predominantly due to accidents which can be removed the next time around. The biggest results were the lack of dangerous psychological issues and the sheer combat prowess of the now dubbed Valkyries.

Going up against robotic drone simulations can only test so much, and so the Valkyries were tested against the Imperial's standard military in simulated combat exercises. It is standard practice in the Imperium, testing newly formed platoons and squads against fortified imperial military installations. They also record and broadcast the fights at later dates, it's the closest the Imperium has to Gladiator arena fights.

Standard Imperial Military strategy for planetside combat is a mixture of air and armor superiority and hitting targets hard. Primarily they hit enemy fortifications with air and ground armor, dire machines and hybrids, and then the swarm of basic soldiers come in for intimidation to force the enemies into surrendering with minimal loss of life. How ever, certain targets are designated as "Nails" for the military to bring themselves down on as "The Hammer of Imperial Might", which boils down to merciless combat, effectively they come in and render the area a parking lot.

Valkyries are intended to be specialized tools, sometimes a precision hammer, others a key, ect. So when they were put up against the standard military formations with certain goals to achieve they achieved them with amazing marks. The combination of physical augmentations and specially designed power armor for each soldier to play to their unique skill sets, along side them being trained together from young ages, made them out perform standard soldiers but they also have amazing group cohesion.

And so with the promise of increasing the number of living finished products the next generation was authorized. As time went on how ever the information of the Valkyries became more well known, such as one interesting bit about them. Valkyries do not retire. Dire machines can be deweaponized and moved to civilian life, literal living weapons of war can retire. Valkyries go through such intense augmentations along with physical and psychological training that they are incapable of returning to civilian life, this was known from the conceptualization of the project and when recruiting they do try to drill home to candidates the gravity of what they are doing, some do decline from this, those who don't become Valkyries.

The second generation of Valkyries had a increase in survivors with a indistinguishable difference in performance from the first generation after excluding 'combat experience' from the first generation. Even with reducing the amount of cybernetics and supplementing it with their suits they were able to complete objectives just as well as Gen 1's. But still a roughly fifty percent loss of life, still deemed acceptable for a third and final attempt. Generation 3's adjusted their cybernetic augmentation to biomechanical, the Inquisitors coming in to assist with not just the psychological training but with the augmentation process.

The Generation 3 Valkyries were far more strict in recruitment as well which resulted in no fatalities from the augmentation process. With the addition of the Inquisitors with a more hands on role with making the Valkyries they were branded as The Imperator's Honor guard. The original intention was for them to be a specialized tool for the imperial military at large, and while that is still the case they are now prioritized as The Imperator's personal soldiers, in part this is to ease tensions of generals having their command hijacked by the Imperator. And when the Imperator departs the mortal coil, the Valkyries can return to their original purpose easily enough.