"Such is the woe cast upon the Domains of the God-Emperor of Mankind in these times that in their wisdom and beneficence, the High Lords of Terra have this day issued this decree: Let there be a Founding of the Adeptus Astartes, and let the foes of the Emperor know that this galaxy belongs to Him, now and forever."
— High Lord Tagus, Convenor of the 349th Congress of the Imperium
New Space MarineChapters are not created piecemeal as required by the Imperium of Man's strategic needs, but rather in deliberate groupings called "Foundings". The process by which a new Founding's creation is approved by the Imperial government is mysterious and arcane, subject to decades or even centuries of planning before it is announced. It is only by an edict of the High Lords of Terra that such an undertaking as the creation of new Chapters can be instigated, for it requires the cooperation and mobilisation of countless divisions within the Imperium's monolithic and vast governmental organisations. Establishing new AstartesChapters on an individual basis is nigh impossible -- the mobilisation of such vast resources is beyond the ability of any single segment of the Imperium.
The Adeptus Mechanicus plays an essential role in the process of a Founding, for its highest echelons are tasked with creating, testing and developing the gene-seed samples that will provide the genetic foundation of the new Chapters. Entire Forge Worlds may be turned over to the manufacture of the mighty arsenal of weaponry, ammunition, Power Armour, vehicles and starships that any such force will require. There are a myriad other concerns as well. A suitable homeworld inhabited by humans must be identified for the new Chapter, which will likely provide not only a secure and defensible base of operations, but also a source of new recruits as well. Such worlds might have been reported by itinerant Rogue Traders and earmarked centuries before by Adeptus Mechanicus Explorators as potential Astartes homeworlds. A degree of environmental terraforming might be required and the natives of the world (if they are to become the source of the new Chapter's Aspirants) must be studied and tested by the Mechanicus' Magos Biologis and Genetors for many generations to ensure they are genetically pure and free of any strain of mutation that might later affect the Chapter itself. The construction of a Chapter's fortress-monastery may be one of the greatest undertakings of all, drawing on the genius of the Imperium's most accomplished military architects and engineers. If the Chapter is to be fleet-based, then even more work must be put into the construction of a Chapter Barque or unusually large Battle Barge to serve as the Chapter's mobile fortress-monastery and all of the related capital warships and Escorts such a highly-mobile Chapter will require.
The already extant Space Marine Chapters may also have a role in this process, though to what degree can vary greatly from Founding to Founding. Many of the First FoundingChapters maintain close links with Chapters created using their own gene-seed stocks, and the Chapter Masters might have a hand in planning future Foundings using that genetic material. It is said that the Disciples of Caliban, a Dark Angels Successor Chapter, was created following the direct appeal of the Supreme Grand Master of the Dark Angels, an extremely rare request.
In the more than 10,000 standard years that have passed since the First Founding of the 20 original Space Marine Legions by the Emperor of Mankind, there have been 25 subsequent Foundings of new Chapters of the Adeptus Astartes; with the most recent, the 26th Founding, occurring in the year 738.M41, approximately 250 standard years ago. Even before a new Founding is announced, entire generations of Imperial servants may have toiled in preparation. Even once the process has been declared and is underway, it is likely to be at least a standard century before the new Chapters are ready to begin combat operations. In times of dire need for the Imperium, faster development has been attempted, but this has often resulted in disaster. Gene-seed cultured in haste is wont to degrade or to mutate, and a great many other factors may lead the entire process astray. And there is no foe more dangerous to the Imperium of Man than a Space Marine who has been corrupted by Chaos or gone Renegade for another reason.
The Creation of the original 20 Space Marine Legions by the Emperor of Mankind is known as the First Founding and it took place at the beginning of the Great Crusade in the late 30th Millennium. It consisted of 20 Legions of Space Marines each made up of roughly about 50 companies divided into various other units in the ascending hierarchy of battle, including Chapters, Great Companies or some other organisation depending on the Legion's own unique naming conventions. The Second Founding, divided the remaining 9 Loyalist Astartes Legions into units known as Chapters which were each about 1,000 Astartes strong after the events of the Horus Heresy in the early 31st Millennium. The Second Founding was deemed necessary by the Primarch Roboute Guilliman in the wake of Horus' betrayal in order to prevent any one person like Horus from ever again possessing the full power of an entire Astartes Legion and the extraordinary threat it presented to the existence of the Imperium. One Chapter from each Loyalist Legion was permitted to retain the original colours, iconography, and name of their First Founding Legion, and these Astartes are known as the Chapters of the First Founding.
New Chapters are only created by an Imperial edict of the High Lords of Terra, and, some whisper, by the sole will of the Emperor of Mankind. The task of actually assembling these Chapters always belongs to the Adeptus Mechanicus. The Adeptus Mechanicus store the gene-seed of all the Adeptus Astartes Chapters which they receive in the form of a tithe. Using lobotomised human test-subjects (most of whom will later be converted into Servitors), the Mechanicus produces new Progenoid Glands. Zygotes of the necessary Astartes gene-seed organs are grown from the gene-seed stores on Mars and implanted into the test-subjects and the zygotes then develop into Progenoids and are surgically removed. A single test subject is used in this way to create two Progenoid Glands, which are then implanted into two more slaves, and so on. Ultimately, 1000 sets of the 19 necessary gene-seed organs to give birth to a new Astartes are created, taking over half a standard century of constant culturing.
The Second Founding of the Space Marines occurred seven standard years after the end of the Horus Heresy, in the early 31st Millennium. This Founding involved the division of the existing Loyalist Space Marine Legions into the far smaller, 1,000-man autonomous Chapters of the Space Marines as decreed by the new Codex Astartes, written by the Ultramarines' Primarch, Roboute Guilliman. The remaining Loyalist Space Marine Legions were divided into smaller Successor Chapters -- one Chapter maintained their parent Legion's original name, badge and colours, while the remaining Chapters took new names and heraldry.
The 3rd Founding was initiated at the suggestion of Rogal Dorn. After more than forty years of preparation, the High Lords of Terra had approved over a hundred writs of succession to both First and Second Founding Chapters. The Ultramarines were granted nine writs of succession.
4th Founding (ca. Late-500's or Early-600's.M32) (Allegedly)
This Founding occurred several standard decades after the climax of the catastrophic events of the War of the Beast - the massive OrkWAAAGH!Warlord known only as The Beast - which laid waste to much of the known galaxy and threatened to destroy Terra itself. Following the successful eradication of the massive greenskin invasion force and the defeat of its Warlord, the Lord Commander of the ImperiumMaximus Thane, decreed that the Imperium would raise as many new Chapters as they had gene-seed in the great vaults of Terra to sustain. All Chapters of the Adeptus Astartes were ordered to release a portion of their Veterans to provide the initial basis for this Founding, the greatest since the First Founding. Gene-seed tithing would be doubled for the next standard century to replenish the vaults. When it was done, there would be hundreds of Chapters to ring the Imperium in adamantium and ceramite instead of dozens.
After enough gene-seed had been collected in the vaults on Terra, the High Lords of Terra authorised the 4th Founding of the Adeptus Astartes, sometime in the latter fifth century or early sixth century of M32, to help bring order to an Imperium rife with civil strife and insurrection, and to help restore Imperial law.
Unknown (Obscure Imperial records list their founding as having occurred sometime during the Astropath Wars in the late M32 or early M33, but other extant evidence suggests that they might have arisen from those Terran members of exiled Raven Guard under the command of Arkhas Fal)
The 13th Founding occurred sometime between the 35th and 36th Millennia and is one of the very rare Foundings of Space Marine Chapters that was not recorded in exact detail. Since the bygone days of the Horus Heresy, the Adeptus Terra has maintained a bank of original gene-seed from every single Chapter ever created, with one notable exception: the 13th Founding, also known as the "Dark Founding." There are no reliable records that indicate how many Chapters were created during the Dark Founding or what became of them. There are only two acknowledged Chapters that were created during this mysterious Founding.
The Chapters created during this so-called 21st 'Cursed' Founding have all suffered from terrible misfortune or some form of genetic corruption or rampant gene-seed mutation, largely because it is believed that the Adeptus Mechanicus sought to "improve" the gene-seed used in the Founding of these Chapters without authorisation from the High Lords of Terra.
The 23rd Founding (also known as the "Sentinel Founding") of Space Marine Chapters occurred sometime during the latter part of the 37th Millennium. Imperial scholars believe that the 23rd Founding to have been one of a series of linked Foundings around this tumultuous period in Imperial history, designed to repair the power and reach of the Imperium'sLegion Astartes which had suffered considerable losses in the preceding millennia.
The Ultima Founding of Space Marine Chapters has recently occurred in the wake of the fall of Cadia during Abaddon the Despoiler's 13th Black Crusade. The scattered Space Marine Chapters of the galaxy have been bled dry over the millennia of ceaseless battle. With the advent of gigantic Warp Storms that swallow whole star systems, the formation of the Great Rift and constant attack by the Forces of Chaos, rampaging xenos and more, the Adeptus Astartes are stretched thinner than ever. With many Chapter planets now actively under siege, some Chapters are confirmed as destroyed or lost, and even those faring relatively well have suffered high casualties and are in desperate need of reinforcement. With the resurrection of the UltramarinesPrimarchRoboute Guilliman, the Avenging Son has assumed command as Lord Commander of the Imperium over all of Mankind's military forces. He has put into action his ultimate contingency plan, 100 centuries in the making -- the Primaris Space Marines. These new transhuman warriors are the next step in the evolution of the Emperor's Angels of Death. They have been genetically altered according to a design laid down by Archmagos DominusBelisarius Cawl of the Adeptus Mechanicus from their brethren to be bigger, stronger and faster. The Primaris Space Marines of the Ultima Founding -- who have been added to existing Chapters as well as raised among entirely new Chapters of their own -- represent timely reinforcements for the Imperium's armies as Humanity's enemies close in for the kill.