Space Marine Inductii
"Trust not the pups whose claws have yet to be bloodied, bearing claws that have never rent flesh, and teeth not yet sharpened upon the hide of a foe."
- – Leman Russ giving his opinion on the Inductii.
The Inductii were raw Space Marine recruits that were inducted into the Space Marine Legions during the Horus Heresy. After the Drop Site Massacre, Battle of Calth, the Burning of Prospero or one of the dozens of other costly battles at the start of the Heresy, most legions found that they had been severely depleted in man power and needed more soldiers to keep fighting the war. As a result every legion would in their own way start mass recruitments of as many viable candidates as possible to try and replenish the losses they had sustained, though as time went on these Inductii would be recruited more and more desperately, slowly eroding the legacy of the Legions and ushering in a generation of cruder Space Marines.
The term Inductii originated with the World Eaters who created vat grown Space Marines on the planet Bodt and would psycho-indoctrinate them with the memories of veteran Space Marines to skip the training process and speed up the recruitment in a Legion that suffered pretty heavy casualties, even before the Heresy (this program came to a screaming halt when Autek Mor had something to say about it).
Training and Gene-seed
When the civil war ramped up to eleven and new Marines were needed as soon as possible, there was not enough time for these recruits to go through the full training that the pre-Istvaan Legionaries had, so all legions had to shorten the training process for their Inductii. For most legions this meant using psycho-indoctrination to give the Inductii years worth of experience in a few hours and throwing them through the harshest training as fast as possible to weed out the weak as quickly as possible, and while faster this process had some side effects of making the new recruits a little mentally unstable, and a bit cruder in terms of tactics. Flash-indoctrination was also used which literally ripped the memories of dead Veterans and uploaded them to the brains of the new recruits, though this was viewed with disgust by many of the Legionaries. Inductii were also only trained in specific tactics that they were expected to be used, such as the Inductii raised on Terra for the Imperial Fists being trained in defensive Siege tactics and fuck all else, while the Raven Guard focused on guerrilla warfare and infiltration. A few legions even skipped the training and said "fuck it, baptise them in fire" and would throw the Inductii into the front line, both as "training" and as meat shields for more veteran Legionaries, a tactic common with the World Eaters and some groups of Blood Angels. Not all the Legions took such a disposable approach to the Inductii, as the Salamanders, Ultramarines, Dark Angels and Emperors Children all trained their Inductii as well as they could and equipped them with better weapons to close any gaps in skill between the Inductii and the other Legionaries, however the Inductii would typically have to go without a lot of the special war gear that had been available to their brothers, simply as there was no longer time or resources to waste on giving every Sergeant Artificer Armour.
The Gene-seed implementation process was also sped up in an attempt to get boots on the ground faster, with the slow multi-phase implementation being thrown to the wind by most legions and multiple implementations being done at the same time. Because of this the Inductii experienced a far higher recruit fatality and Gene-seed rejection rate than before, as well as Gene-seed flaws becoming more prevalent, such as the Thousand Sons Inductii experiencing more cases of the Flesh Change. In a few cases, certain Gene-seed was skipped or not implemented to speed up recruitment. Some of the Word Bearers deployed to distant war zones would not implant the Black Carapace until after an Inductii's first battle, with the survivors having earned the right to use power armour AFTER their first battle. The Iron Hands would supplement certain organs with forbidden Dark Age of Technology augments, as it was faster to build and implant these augments than it was to grow and implant the Gene-seed organs, and it helped ease some the problems of collecting the Iron Hands Gene-seed when most of it had been lost after Istvaan V.
Some of the more stable parts of the galaxy could take more their time with the Gene-seed implementation process, for example the Ultramarines relied solely on different training techniques to speed up the creation process and kept the Gene-seed implementation process the same, and the Imperial Fists on Terra could also take longer with the Gene-seed implants as they waited for Horus, however still decided to shorten the process by delaying the implantation of the Betcher’s Gland and Sus-an Membrane, as their functions were seen a non-factors for the fighting that was to come to Terra. This meant that the both the Betcher's Gland and Sus-an Membrane atrophied in the Imperial Fists and would over time would become non-functional throughout the Legion and later Chapters. For the legions who hadn't had the luxury of time, the rushed implementation process of the Gene-seed left it permanently degraded and damaged, and would led to long term effects such as the already mentioned Imperial Fists flaws, and it most likely contributed to the flaws and malfunctioning organs seen throughout the post-heresy Chapters, such as the Raven Guard and Space Wolves.
As far as equipment goes, as you can see from the images, initially, nearly all Inductii were given the advanced Mark VI: Corvus Armour. Why that was the case was unknown given that the Beakie armour was incredibly new and costly to make at the time of the Horus Heresy. Whatever was the case, it was likely that the issuing of Beakie armour did not last long as demand outstrip supply, so as time went on, the majority of the Inductii like their Legionnaire seniors, wore Mark V: Heresy Armour as supplies grew low. For weapons, it varies a lot since the roles of an Inductii differed from legion to legion.
Culture shock
The Inductii were typically looked down on by the Great Crusade veterans, being seen as the new guy and many legions would not be happy about the influx of new recruits who weren't versed in the cultures of the Legion. The term "Inductii" was only wide spread through the Traitor Legions, as it had come to be a byword for "Abomination" and "Shame" due to their bio-heresy origins with the World Eaters, and while other Legions Inductii weren't (ironically) as heretical with their production they were still seen as an inferior breed of Space Marine and would typically be shunned and not given the same privileges as their older brothers, such as the Sons of Horus banning Cthonian symbols and imagery on their Inductii. The Loyalists typically had their own names for their Inductii, with the Imperials Fists on Terra calling them Neophytes or Sentries, they usually shared the traitors opinion of the Inductii being lesser than what had come before them with one Imperial Fist commander lamenting the raising of the Inductii, seeing it as the knowledge and legacy of the Great Crusade being bled away and replaced with an untested and undisciplined rabble.
Despite this divide between the Legionaries and the Inductii, both were physiologically nearly identical with the Inductii having all of the same Geneseed and traits as the Veteran legionaries (admittedly with a bit more genetic deviation and flaws on the Inductii's side with the rushed implementation process they would go through), and the combat capabilities of the Inductii were on-par with the other Legionaries. The distinction between the Legionaries and the Inductii was primarily cultural, though to be fair this cultural division was not just fostered by the original legionaries, with plenty of the Inductii not acclimatising or embracing the Legions cultures.
As the Legions grew desperate they started looking for more recruitment pools which meant recruiting from populations outside of the Legion home worlds and recruitment worlds, with little to no similarity to the cultures worlds that had fostered the Legions original cultures. This sort of culture clash had occurred in a few of the Legions when the Terran marines were reunited with the Primarchs and started butting heads with the new marines from the new Legion home worlds, but the recruitment of the Inductii brought back these problems back and more. As the Legions mass recruitment brought in more and more of these Inductii from differing cultures, the Inductii were increasingly separated into their own companies and battalions where they would foster their own culture by mixing the traditions of their home world with those of the legion, or outright rejecting the Legions traditions and creating their own. This naturally increased the friction between the Inductii and Legionaries and with most attempts to bridge the gap between the two groups ending in failure. By the time of the Siege of Terra, most Legions were internally fractured between the remaining Legionaries from the Great Crusade and multiple groups of Inductii.
Ironically (or suitably depending on your point of view), the Inductii would be the ones go on to re-define the characters of the Space Marines in their new Chapter forms, as a lot of quirks and flaws that would become present in the Chapters started with the Inductii, being fostered with the Inductii companies and their use during the heresy. The Iron Hands technological obsession was fostered in the Inductii due to their extensive augments, the Space Wolves Inductii acting as proto-Blood Claws and the increased geneseed degradation saw far more Wulfen appear in the Legion, and even the defining tactics for many post-heresy chapters, such as the introduction of special weapons into the Tactical Squads were first seen in the Ultramarines Inductii. Many Inductii companies would also go off and form their own Chapters during the Second Founding, separate from their parent Legions which probably explains chapters like the Mortifactors being so different from thier parent legions.
In truth, the Inductii were not the last warriors of the Legions. They were the first Soldiers of the Chapters.
