Guilliman’s Great Folly: The Codex Astartes Legacy – Prime

Welcome back to the conclusion of our deep dive in the Codex Astartes, a deeply flawed document/system. Today we look at its legacy on the Imperium in a ten-thousand word exhaustively researched piece.

In part one of The Index Astartes: Guillman’s Folly, we looked at some major issues having to do with the size of Space Marine Chapters. In particular, we discussed their inability to respond to significant threats, their inability to absorb losses, their insignificance on a galactic scale, and the inefficiency inherent in their size. Here in part two, we will finish up looking at major flaws and examine the problems related to the lack of an overall Space Marine command organization. We will also address any successes of the Codex and what lessons we can take from the things we’ve looked at.

Part 3: A Question of Command

Out of fear of another large scale uprising, Roboute Guilliman broke the massive Space Marine Legions of the Great Crusade and Horus Heresy up into the small modern Chapters. In doing so, he purposefully failed to create an overarching command structure for the Space Marines. A choice which has had dire consequences for the Imperium. The lack of an overall command structure has lead to disorganization, failures of communication, and civil war, and has exacerbated all the issues we looked at in the prior section.

Under the Legion system, each Space Marine Legion was an army and, in many ways, a nation of its own. Legions are comprised of hundreds of thousands of Space Marines, as well as millions of attached Imperial Army troops, thousands of void-ships, and a massive logistical and supply chain. Each Legion was able to wage multiple simultaneous wars, and its size and command structure gave it strength.

At the head of each of the eighteen Legions was a Primarch.

At the head of each of the eighteen Legions was a Primarch. The Primarch, in turn, reported directly to the Emperor of Mankind and possibly his adviser Malcador the Sigilite. This was a straight forward organization that grouped the offensive might of humankind into eighteen large formations, bolstered by sector and local forces tasked with defensive roles. Towards the end of the Great Crusade there was an attempt to further unify the Legions’ command, first by appointing a Warmaster to oversee operations in the Emperor’s absence, and second by ultimately placing the Legions under the command of the Imperial ruling council, the High Lords of Terra. With this system, the Legions not only had large scale command and control groups but an overall directing hand guiding them.

With the Codex, Guilliman replaced a logical and large scale organization with over one thousand smaller groups with no defined chain of command. Each Chapter Master effectively acts as the ruler of a small fiefdom, with almost complete independence and little oversight. While nominally under the control of the High Lords of Terra, many Chapters give only lip service to following orders, and there is little actual control. Indeed, without a more significant organization overseeing the Space Marines and reporting to the High Lords, we are more or less left with a thousand individual Chapter Masters infrequently reporting to Terra.

Some of the First founding Chapters have maintained an informal larger organizational structure. In these cases, successor Chapters maintain firm bonds with their founding Chapter and when needed will work together, often different to the overall command of the founding Chapter’s Master. This was the case both during the Devastation of Baal when the majority of Blood Angels successor Chapters placed large numbers of their troops under the command of Dante and during the War of the Beast when the Imperial First‘s Last Wall protocol was activated⁹. However, these associations are informal and tenuous at times. In almost all cases the direct support and command of non-Space Marine forces have been removed.

In effect what we see here is the feudalization of the Space Marines – moving from a formal, centrally controlled organization to a large number of smaller, uncontrollable, groups, with some owing allegiance to others. This plays well with the similarities between the Imperium’s decline and the fall of Imperial Rome and the coming of the Dark Ages that the setting often invokes. It is, however, a horrible way to organize a military force.

Many of the issues we discussed in the prior section could be at least partially alleviated by putting a more extensive command structure in place. In particular, the inefficiency of the system could be better addressed. Space Marine formations would be better able to react to large threats if directed by a central command as well. Moreover, their forces could be used to better effect. No longer would we have situations where Marines are deployed halfway across the Galaxy to meet a threat, while other forces are then shuttled across the galaxy to meet a danger near the first Chapters homeworld (as we see with the Blood Angels First Company during the Fall of Cadia and the Devastation of Baal).

Space Marine formations would be better able to react to large threats if directed by a central command.

In many situations, we have seen that an ad hoc larger command structure can be enforced – with a particular leader rising to command a mixed and considerable force of Space Marines. This however, only tends to happen in extreme situations and as a reaction to a disaster. At this point, the newly organized Space Marine force can only hope to contain the damage, rather than prevent it. Also, such formations usually are only useful when there is a leader of sufficient status and acumen for one to form around.

Overall the lack of any overarching command organization exacerbates all the issues stemming from the small size of the Codex Chapters. It prevents efficient use of Space Marines and much coordination, and ensures a lack of real oversight. One need only to imagine if in the modern US army each battalion, instead of working within an overall command structure of regiment, division, corps, army, etc. reported directly to the President and Cabinet. That ridiculous situation is more or less how the Space Marines operate.

Part 4: The Results of an Unnatural System

Now that we’ve looked at some of the major flaws of the Codex system. We will look at how these flaws have shaped both the Imperium and the Space Marines. We’ll also dig into if the Codex was effective in achieving any of its goals.

Space Marines are at their best when deployed en masse as shock troops.

Space Marines were not designed to fight the way the Codex Astartes forces them to. As designed by the Emperor of Mankind, they are supposed to act as the cutting edge of humanity’s armies. Space Marines are at their best when deployed en masse as shock troops. The Imperium’s greatest victories and times of expansion, the Great Crusade and the Indomitus Crusade, were marked by the deployment of large formations of Space Marines.

It was these mass deployments that first birthed the Imperium and later saved it from the brink of disaster. Again and again, we’ve seen that the greatest crises are often only salvaged by the mass deployment of Space Marine forces. This is how the Emperor designed them to operate; and Guilliman, upon his return seems to have recognized that and used them in the same manner.

The Codex and the Chapter system has forced Space Marines to operate in a far different manner. Large scale deployments are very rare for Space Marines. Due to the Chapter system, they’ve been forced to move from acting as shock assault armies to special forces troops. The normal Space Marine deployment is as a small group, often Squad sized, to complete a specific special mission. While Space Marines, due to their natural martial prowess, are capable of accomplishing these missions and are even good at them, they are often not the only forces would or could have carried them out. The Imperium has many forces at its disposal that could carry out special operations – from elite Imperial Guard units to Assassins and operatives of the Inquisition. They have only one power capable of carrying out the kind of massed shock attacks the Space Marines can, and it is being wasted.

Thus the Codex has forced the Adeptus Astartes, and the Imperium as a whole, into a losing fight. The Space Marines have been forced to fight a thousand small holding actions, slowly losing ground. Each crisis weakens the Imperium a little more. The weakness of the Space Marines prevents the Imperium from ever delivering a knock out blow to its enemies and has caused a string of half victories and stalemates.

The Space Marines have become a reactionary force, staving off total disaster but slowly inching towards the brink. Like Rome during its decline, the border is again and breached by invaders. Though the invasion is thrown back or absorbed one by one, the structure weakens dally. By purposefully weakening the Space Marines with the Codex, Guilliman crippled the Imperium.

Guilliman… chose to weaken the Space Marines

At this point, seeing the flaws, and recognizing that to a degree they are intentional, we should ask of the Codex was at least successful in its goal of curbing Space Marine power. Guilliman, after all, chose to weaken the Space Marines and divide them so that no one group, or leader, would command the power that the Primarchs at the head of their Legions did. This was not only to prevent another civil war like the Heresy, or a Space Marine lead coup, but also to prevent the large scale defection of Space Marines to Chaos again. So was Roboute successful? Not really.

Looking at the history of the Imperium, we can see that the Codex system failed to prevent major civil wars. The Imperium has had its share of internal conflict, such as the Nova Terra Interregnum, which saw the Imperium Split in two for nearly a thousand years, or the Age of Apostasy which saw civil wars with a loss of life on the scale of the Heresy; or more recently the Macharian Heresy which saw the thousand worlds the Lord Solar had conquered fall into disarray and war¹⁰. While these might not have quite equaled the horrors of the Heresy, they came close and likewise pitted Space Marines against Space Marines. The Macharian Heresy was only ended by the deployment of one hundred Space Marine Chapters. It is likely that a more unified Space Marine front could have prevented the other major civil wars, or at least ended them sooner¹¹.

Nor did the new Chapter system prevent Space Marines from staging coups and taking control of the Imperium. During the War of the Beast, both Chapter Master Koorland and Maximus Thane of the Imperial Fists staged coups and declared themselves Lord Commander of the Imperium, effectively taking control of the government for a time. The Primarch Vulkan upon his brief return to Terra around 545.M32 also seems to have seized control of the Imperium. And of course, Guilliman on his own return to Terra after his rebirth has taken control of the Imperium as Lord Commander and regent. All without the need of a Legion. Indeed, the lack of large scale organized Space Marine resistance likely made these takeovers easier.

It must be conceded that the Chapter structure has at the least prevented the losses of Space Marines to Chaos, at least on the scale as seen during the Heresy. There have been no more Legion sized defections. Arguably only a corrupted Primarch would have the force of will to take that size force with him into damnation, and even when the traitor Legions fell, many within their ranks remained loyal. Of course, the Chapter structure has not prevented Marines from being corrupted. There is a constant stream of Marines giving into the forces of Chaos, as individuals or small groups. Large scale defections are not unheard of, either. The renegade chapters known as The Scourged, The Flawless Host and The Crimson Slaughter were all once loyalists who converted to worship of Chaos Gods as whole Chapters¹². During the Badab War, four whole Chapters fell en masse, and other large defections on this scale or lager have happened.

A single Chapter is a much smaller, and easier, target to corrupt than an entire Legion.

Indeed the argument could be made that the Chapter system has made Space Marines more susceptible to corrupting influences. By removing an overarching command stricture and limiting oversight to the often ineffectual, or misguided, efforts of the Inquisition, corruption is often allowed to go undetected. Due to their independent and insular nature, it is not hard for a Space Marine Chapter to be corrupted from within without anyone noticing. It is said that often the first sign of a Chapter’s corruption is when it launches attacks on once friendly assets¹³. Moreover, a single Chapter is a much smaller, and easier, target to corrupt than an entire Legion. By dividing the Legions, Guilliman gave Chaos small and temptingly isolated targets to corrupt. Thus the Codex has at best been only partially effective at preventing corruption and, at worst, exacerbated the issue.

At this point with the flaws of the Codex piling up, some may think I’m being unfair here – after all the Imperium HAS survived. For ten-thousand years, the Angels of Death has held the line and humanity has endured. Surely then in the ultimate test, the Codex has passed, keeping alive humanity’s flame in a grim and dark galaxy. And yet, I would not call it a victory. Humanity and the Imperium have survived more in spite of the Codex then with its help. The designed martial prowess of the Space Marines has gone a long way towards making up for the failings of Codex and Chapter. Nor could the Space Marines have done it alone. Only the sacrifice of untold trillions and often literal divine intervention has staved off destruction. Again and again, it is the billions of baseline humans who suffer and die buying time for the transhuman Marines to get their act together and take effective action. Left to the hands of the Chapter’s alone the Imperium would have crumbled millennia ago.

And what an Imperium the Space Marines have saved. Ten-thousand years of half victories and narrowly staved off disasters have killed the bright dream of humanity. Each Space Marine victory leaves more worlds devastated and the Imperium a little darker. Hamstrung by the Codex, the Space Marines can not effectively carry out their duties. The dark Imperium Guilliman returned too, and so dislikes, is in large part his creation thanks to the Codex. The slow decay and the long losing battle were his gifts to future generations.

The slow decay, and the long losing battle were Guilliman’s gift to future generations.

Nor would the Chapter system have been successful much longer. Like the later Roman Legions or the small Byzantine Themes, the Chapters were failing. Again and again, Xenos and Chaos incursions broke the defensive lines wreaking havoc and eating away at Imperium power. Though both Roman Empires and Human Imperium could, for a time, marshal forces to contain the threats and drive them back. The situation in all cases could not last forever, for all Empires there come, at last, a breaking point.

For the Chapter system, that breaking point was 999.M41. In that year two major invasions struck the Imperium which it could not repel. At Baal, the Chapters of the Blood made their last stand against the hordes of Hive Fleet Leviathan. After a disorganized and ineffectual initial resistance, even this great gather of Marines was too few to stop the Tyranids¹⁴. By all rights, the Blood Angels and their successors should have been wiped out. Without a Legion sized force to oppose them all of the Ultima Segmentium would have fallen, and it’s likely the Imperium would have been doomed.

At the same time in the galactic west, Abbadon the Despoiler threw his 13th Black Crusade against the Cadian Gate. Though parts of some forty-three Chapters rallied to the defenses of Cadia, they were hampered by all the weaknesses of the Codex. Maybe a Legion fighting united could have stopped Abbadon, the Chapters could not, and Abbadon broke Cadia (though never the Cadians) and opened the Great Rift. The Cicarix Maledictum should have been the end of the Imperium. It was a cataclysm the Chapter system could not deal with.

Isolated and weak many Chapters were destroyed by the tide of Chaos that broke into the material realm. Nearly half of the Chapters active at the time of Cadia’s fall were unaccounted for, and many are known to have been entirely wiped out, either by warpborn cataclysm or in the Chaos attacks that followed¹⁵. Abbadon, like Alaric on Old Earth, had broken the defenses of Empire and nothing could stop him. Legions might have weathered the storm, Chapters could not. The Fall of Cadia was in many ways the Imperium’s Manzikert, and with a similar immediate result. Alone, either the Chaos invasion or Leviathan would have brought down the Imperium of Man. Both were simply event the Chapter system, with all its flaws, could not handle.

In the end, it was Space Marines that saved the Imperium. But they did not do so using the Chapter system. It was the Indomitus Crusade that drove back the forces of Chaos and stabilized the Imperium in the wake of the Great Rift. Likewise, it was this Crusade that relieved the defenders of Baal and finished off that tendril of Leviathan. The Crusade, however, did not fight as the Chapters of the Codex. The bulk of the Crusade was made up of the new Primaris Marines.

While many of them fought in Chapters, many more, especially in the Crusade were part of the Greyshields. The Greyshields were nine, one for each loyal Primarchs gene-line, massive, Legion sized, formations. They specifically did not deploy in Codex approved formations, but often fought in massed Legion sized groups¹⁶. Thus at the end, the Chapters and the Codex had failed, and only the old Legions could save the day. We must say that in the end, the Codex failed.

In Guilliman’s defense, he seems to have recognized the weakness of the Codex. Indeed, he designed it to be weak. It’s likely the Codex was never meant to be a permanent solution but was rather a stop-gap put in place in the aftermath of the Heresy. Guilliman probably would have revised and changed it as needed. Only his untimely wounding by Fulgrim and millennia in stasis prevented this and elevated it to the status of a holy text. When he wrote it, Guilliman could never have envisioned that it would be in place for ten-thousand years.

The Primarch of the XIII clearly recognized that the old Chapter system could not win the day.

Indeed there can be little greater truth of the Codex’s weakness than the fact that Guilliman worked to abandon it almost as soon as he returned. The Primarch of the XIII recognized that the old Chapter system could not win the day in against the situation it faced. Not only did he alter the Codex almost at once but it was he who chose to employ Marines in older Legion style fashion. It’s telling that the Imperium’s greatest tactical mind feels that Space Marines are best used in large scale assaults. Moreover, we know Guilliman plans to replace the old Codex with a new version.

At the end of the day to be effective, the Space Marine structure needs to be revised. The Chapter’s are simply too small to carry out their duties. While the old Legions of one hundred thousand or more may be too risky to bring back, smaller forces of ten-thousand or so would be a good comprise. Also, the Space Marines need an overarching command structure. To a degree, they have one in Guilliman himself, and his staff, but a more permanent organization that’s less focused on one man would be better. The great battles of the Forty Second Millennium will be decided not by Space Marine squads, but by massed formations of Marines.

Intentional or not Guilliman’s Codex has held sway for ten millennia, and for that time it has shackled the Space Marines and held them back. People often note how much ground was gained, and how many victories were won during the Indomitus Crusade compared to most of the Imperium recent history. This is a testament to what Marines can achieve when not held back by the Codex and the Chapter structure. Ultimately the Chapter organization proved a weakness to the Imperium, and in its most desperate hour would have failed.

In Conclusion

Born of fear, the Codex Astartes was effective only in limited the power of the Space Marines. In its attempts to prevent civil war, coups, or the corruption of Marines, it failed, and possibly made things worse. Thanks to Guilliman humanity was gifted with a flawed sword, incapable of ever winning the Long War. It was Guilliman’s mandated Chapters, more than even Horus perhaps, that condemned his father Empire to a slow decay. Guilliman did what all the forces of Chaos could not, and destroyed his father’s greatest weapon. Well intended or not, it’s clear now the Codex Astartes was Guilliman’s great folly, a folly humanity has paid for with oceans of blood and ten-thousand years of darkness.

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1. Guy Haley. The Devastation of Baal. (Notthingham, Black Library, 2017), pg 32
2. Games Workshop. Warhammer 40,000. (Nottingham. Games Workshop. 2017), pgs. 44-45
3. ibid, pg.45
4. Games Workshop. Codex: Chaos Space Marines (Nottingham. Games Workshop. 2019), pgs. 50-51
5. Ibid., pg. 50
6. Guy Haley. The Devastation of Baal. (Nottingham, Black Library, 2017), pg. 484
7. Warhammer 40,000, pg. 51
8. Dark Imperium, Pgs 107-108
9. Guy Haley. The Devastation of Baal. (Notthingham, Black Library, 2017), pg 32
10. Games Workshop. Warhammer 40,000. (Nottingham. Games Workshop. 2017), pgs. 44-45
11. ibid, pg.45
12. Games Workshop. Codex: Chaos Space Marines (Nottingham. Games Workshop. 2019), pgs. 50-51
13. Ibid., pg. 50
14. Guy Haley. The Devastation of Baal. (Nottingham, Black Library, 2017), pg. 484
15. Warhammer 40,000, pg. 51
16. Dark Imperium, Pgs 107-108

Author: Abe Apfel

Abe is that rare thing, an Austin local born and raised here. Though he keeps on moving around, DC, Japan, ETC., he always seems to find his way back eventually. Abe has decades of experience with a wide range of tabletop and RPG games, from historicals, to Star Wars to D&D and 40K. He has been contributing to BOLS since almost the start, back when he worked at and then owned a local gaming store. He used to be big into the competitive Warhammer tournament scene but age has mellowed him and he now appreciates a good casual match. He currently covers 40K tactics and lore, as well as all things Star Wars, with occasional dabbling in other topics. Abe remains in mourning over the loss of WFB to this day.