Editing Codex Astartes

{{Topquote|The Codex Astartes is a set of rules. They guide us. Shape us as Ultramarines. Teach us how to hold duty and honor sacred above all. But how we live with those rules is the true test of a Space Marine.|[[Captain Titus]], [[Ultramarines]] 2nd Company}}

{{Topquote|They tell me Guilliman wrote a book- maybe, with all that time on his hands, he might have seen this coming.|Leman Russ, during the Horus Heresy}}

{{Topquote|[[If the Emperor had a Text-to-Speech Device|So, I accepted the book and gave it a five out of ten "it was OK" review.]]|Rogal Dorn}}

{{Topquote|But NO! You succeeded because you were trained by the book. The holy codex of our OH SO WONDERFUL I COULD SHIT MY '''POWER PANTS''' Spiritual Liege|[[If the Emperor had a Text-to-Speech Device|Marneus Calgar's true thoughts on the Codex Astartes]]}}

The '''Codex Astartes''' (a.k.a Codex Asstardes) is the collective name given to a series of tactical and organisational guides written by [[Roboute Guilliman]] over the course of his life, compiled at the end of the [[Horus Heresy]]. The Codex's organizational mandates split the remaining [[First Founding|Space Marine Legions]] into smaller chapters for reasons discussed below. It also includes many tactical doctrines and stratagems for just about every situation, like the formidable [[Steel Rain|STEEL REHN!]] Most loyalist Space Marine chapters follow the Codex Astartes to varying degrees, with [[Ultramarines]] and their successors seeing it as literal holy writ while some chapters like the [[Black Templars]] and [[Space Wolves]] merely see it as a book of tactics to be referred to when necessary. Most chapters fall somewhere between those two extremes, using the codex but making adaptations where necessary (the [[Imperial Fists]], for example, use the Codex, but have a special appendix on how to Fist better, called the Book of Five Spheres. I guess Dorn was a fan of Musashi?). Generally every Chapter does still respect it as it ''is'' the brilliance of a Primarch; even the Space Wolves do respect its teachings although they view it much like how modern officers view The Art of War.  Almost all chapters will make a few minor alterations at the very least, usually just superficial things accounting for the chapter's culture and occasionally major organizational changes due to needs or wants. Now that Guilliman woke up, odds are he's going to update the codex like a fa/tg/uy updating his army lists, so the boys in blue should have some new reading material soon. Fortunately, since he's been adding Primaris Marines to Chapters that already have a thousand Marines, Guilliman has probably thrown out the number limit thing, realizing it was really stupid (or that no one noticed the Great Crusade never officially ended and so all Chapters are technically crusading and so have no number limits in the first place).

Now if only he would realize all of the most successful asskicking Chapters or uniquely effective formations specialize in close combat, as if the Emperor gave Astartes super-human bodies to actually use their super-strength instead of shooting guns normal humans in powered armor can use.  [[Executioners]], [[Space Wolves]], [[Black Templars]], [[Space Sharks]], the list goes on.  The Ultramarines and Imperial Fists are glaring exceptions but both of them operate more like super Tempestus Scions/Stormtroopers than super Guardsmen, unlike most Codex compliant Chapters which unfortunately heavily trend towards the power armored Guardsman behavior.

==What the Codex set out to Accomplish==

The Codex Astartes was written with three main purposes in mind. 

First, the Codex is a tactical and strategic guide, containing tips and plans on how to handle nearly any battle situation imaginable and then some. The Codex served with flying colors until the modern day of the setting when its weaknesses began to show against certain [[Tyranids|unconventional]] [[Necrons|enemies]]. Much like ''The Art of War'' or the FBI tactical guidebook, if you can get your hands on a copy you can anticipate the actions of those that use it, but countering it is '''really''' fucking hard because of just how comprehensive the Codex is. It doesn't just tell you "When your enemy is doing B, do C to counter it," it also says, "And when the enemy counters C with X and Y, use Z to shut down their counter." In real life warfare, soldiers have a hard time adapting to new information under pressure, which is why commanders need to limit the orders they give to their troops and keep them as unambiguous and simple as possible; drilling them on exactly what to do in a given situation, especially in such a comprehensive manner, does have its advantages since it reduces mental clutter. Sun Tzu's ''Art of War'' is still being taught millennia after its publication; now imagine that same spark of tactical genius manifesting inside the mind of a superhumanly intelligent demigod. The Codex isn't perfect - no tactical treatise is - but it's damn close.

Second, the Codex is an organizational guide. Guilliman was a flawed genius, an organizational savant literally unmatched in the galaxy and more than a little OCD when it came to detail. Beyond simple mandates about the composition of the Chapters, the Codex contains information on the minutia of administration, with details on every subject from bolt shells to bread, water distribution to weapon production, organization of auxiliary forces, suggested countermeasures to [[Nurgle|viral]] outbreaks, training schedules, troop morale, ammunition production, distribution of that ammunition to terrestrial and naval combat units, how large reserves can be built up, how long those reserves will last when production stopped, ration distribution for militant and civilian populations, how those rations can be stored, food cycling to avoid waste, integration of chain of command with allied and auxiliary forces, integration of militia into formal military, suggested staging area locations relative to battle lines, suggested landing area locations relative to battle lines, prioritizing access to and from these areas, [[derp|guides to avoiding massive compound sentences]], fortification locations, demolition strategies for those fortifications in the event that they must be abandoned, and more. It also has plenty to say on how to live your day-to-day life with everything from codes of honor to follow, to how your boots should be laced. Seriously, the Codex can tell you how to spend every minute of your life from birth to death, and pretty much every part of it is either acceptable or outstanding if admittedly inflexible. Much of it, if applied to the Imperium as a whole, would also solve most of the grimdark.

Finally, and perhaps most importantly, the final version of the Codex is designed to keep the power of the Imperium decentralized. At the end of the Heresy, Guilliman wanted to ensure there wouldn't be any repeating performances of the strife that had gripped the galaxy. To this end, he tried to unite all Astartes into a single Legion but the High Lords went ape shit about this so instead he split the Imperial Army into the [[Imperial Navy]] and the [[Imperial Guard]] and broke up the Legions, to keep one person from ever having the power to cause such massive chaos. Whether or not this was a good move is [[skub|a subject of ongoing debate]]. Detractors would point out that the newly decentralized and feudal Imperium is nowhere near as capable of unified action as it was before the heresy, pointing at how this decentralization screwed the Imperium over during [[the War of The Beast]], while its defenders would point out the examples of The [[Badab War]] or the [[Macharian Crusade]] as examples of too much centralized power devolving into a clusterfuck, to say nothing of the Horus Heresy demonstrating why giving any one person too much power over the Imperium is a ''very bad idea''. But, really, the problem in all examples of too much power under one person was A) that person not being carefully watched by someone else and B) everyone under them being indoctrinated for mindless obedience to orders.  Considering the Imperium has solved A but still heavily emphasizes B, it really could go either way. A large scale rebellion isn't really something the Imperium needs to fear regardless of who has how much power as people will rally to anyone they believe in, but someone with power over a lot of forces could easily deploy them in ways that strategically weakens the Imperium.  It's not uncommon for corrupted/traitorous commanders to send regiments into traps, for example.

However, one thing that people often forget when they argue about whether Legions or post-Heresy Chapters are better is that the Legions and Chapters have very different roles. Legions of a hundred thousand Astartes are great when you want to steamroll the galaxy - which is exactly what the original Legions designed for - but not so great when you want to maintain peace in a sprawling galaxy-spanning empire. What the post-[[great Scouring|Scouring]] Imperium really needed were small-scale elite rapid-response forces, which is exactly the kind of role that the Chapters are most suited for. Well, that coupled with a large normal army to act as first-responders very quickly and hold the line for the big boys to come smash face.  Come to think of it, this is very much like how real life destroyers worked in WW2, how infantry work in a mechanized infantry unit, and other such things.  Fitting, since Space Marines are basically living tanks.

This is also a much more efficient use of the Astartes. You don't need a space marine to man a gun line or garrison a fort - why let a marine do a guardsman's job? - and considering how long it takes to create a fully-fledged Astartes, you'll want to get the most out of every single one of them. Remember also that there weren't all that many loyalist Astartes left alive after the Heresy. Getting a thousand Astartes killed just to win a battle may have been A-OK during the Great Crusade or the Heresy, but the post-Heresy Imperium just couldn't afford losses like that anymore (for a while, at least), so it only makes sense for the space marines to conform to tactics where your average space marine battle will result in few marine casualties. Guilliman designed the Codex marine armies to be modular, precise, and efficient in ways that the original legions weren't. 

Of course, the tradeoff is that the marines are no longer well suited for large-scale warfare. But large-scale warfare and armoured warfare are now the Imperial Guard's job, anyway. On top of that Legion-sized (or at least multichapter) deployments can and will still happen whenever necessary, like with the [[Armageddon|Armageddon wars]], the [[Black Crusade|Black Crusades]] or the Wall of the Imperial Fist Legion during the War of the Beast. That said, there are situations in M41 where the Legions of old would probably be more effective than any gathering of Chapters: the [[Tyranids]] and the bigger [[Necrons|Necron]] dynasties come to mind, though there's also less formidable threats like the [[Tau]]. But even there the Guard is a perfectly fine substitute for a Legion in most if not all of those cases, especially with their godly mechanization, tanks, and artillery.  Hell, their standard procedure is to simply use various artillery to eradicate everyone and everywhere the enemy could hide (bunkers, trenches, buildings, tunnels, ''anything'') then send in tanks to wipe out any resistance and the ground pounders to hunt down the survivors.  We have billions of Guardsmen dying every day, but the number of Guardsmen makes billions a day look like literally a drop in a literal ocean. This means that the Astartes are not needed nearly as often as the Guard, especially since the Guard almost always operates on the defensive, which means that line-breaking supersoldier armies are rarely needed.

Interestingly enough, the original version of the Codex had no plans to break apart the Legions at all. Instead, it proposed their unification into a single Legion formed from multiple self-sufficient Chapters, which would merge and break up as needed regardless of which Primarch they descended from. While this may have been able to preserve the advantages of being a Legion better, the other [[High Lords  of Terra]] were scared shitless by the idea of the Space Marines unifying and promptly rebelling a second time, so the original plan never came to pass. Even the idea of it happening was enough for the 41st millennium-era High Lords to plot Guilliman's overthrow when they heard he might resume his old position, which shows how little they know.  The Primarchs are the sons of the Emperor for a reason.  They are '''''really fucking scary dudes'''''.  Besides, the Space Marines would unify as much or as little as they choose and there really isn't anything the High Lords can do about it so their concerns over Guilliman's original intentions for Chapters didn't matter and the changes didn't either. They still operate the same way Guilliman had intended but with far less communication and co-ordination unless they needed.  Since they usually aren't needed, it doesn't really matter at all.

When Guilliman was finally revived, he began to see the flaws that came from strict adherence to the Codex Astartes which were partially his fault from paranoia after the Heresy, and others that had arisen as he wasn't around to correct them given he spent nearly ten thousand years in stasis moments from death. Thus, he has begun reforming its guidelines and got rid of several of its restrictions on Space Marines. He currently hopes to replace it entirely with the Codex Imperialis - a tome that won't just describe how to organize and direct the Adeptus Astartes or even the other [[Imperial Guard|Imperial military forces]], but Imperial governance as a whole possibly down to the ideal daily lives of every Imperial citizen, likely in an attempt to make the entire Imperium [[NobleBright|look and operate as smoothly as Ultramar]]. Needless to say, this will probably be the size of a 10 volume encyclopedia, and still hasn’t been finished.

==Chapter Organisation==
Under the Codex Astartes, the Space Marine legions were to be split into groups of 1000 fighting men called a [[Space Marine Chapter|Chapter]]. While many people assume this means a chapter is composed of 1000 men, this is a bit misleading because that number does not include the chapter's upper echelons, support structure, auxiliary units (now including Scouts), dreadnought-interred veterans, the Librarius, honor guard, or other specialists (Techmarines, Apothecaries, Chaplains, pilots, permanent shipboard crews etc); this means that a chapter will commonly have upwards of 1100 space marines while still being codex compliant (1000 Brothers and Sergeants on the line, the rest officers and specialists) and many chapters will have large units of mortal retainers (including thousands of Voidship crew in their fleet) to serve as auxiliary forces. It's not uncommon for a chapter to have tens of thousands of soldiers to call upon, though only a minority of them will actually be Adeptus Astartes. It's important to note that the Chapter was already an existing subunit within the pre-Heresy legions, and those were organized much as they were in the Codex. Astartes chapters maintain a [[Fortress-Monastery]] that serves as their home and may maintain other garrisons as well. Fleet-based chapters are addressed below.

It should be noted, however, that the numbers of Veterans in a Chapter is not limited. Most Veterans choose to stick with their parent Battle Company. Considering how the training pipeline goes from the Scouts and through each Reserve Company, some might suggest the Space Marine Chapters treat the Battle Companies as a final training and test and then make those who pass into Veterans to circumvent the recruitment limitations.  That they have not change recruitment practices and rates despite their numerical limitations is at least a little suspicious and confusing.  Then there's the Imperial Fists recruiting from countless worlds plus Terra yet somehow have only a thousand Marines.

By the 42nd Millennium, the reawakened Guilliman has set about redrafting the Codex Astartes to accommodate the inclusion of Primaris Marines, who do not form the same sorts of squads as their traditional brothers. However he has not massively changed the organisational units of "Chapter" and/or "Company". With the new codex, the space marine company is still 100 men on paper, but can be organised in a far more flexible arrangement of squads and can accommodate additional squads drawn from reserve companies. It also means that whole Companies (or even Chapters) of Primaris Marines can be formed without the  need to makes exceptions for them.

The 1st Company is composed of [[Veteran Squad|Veterans]], and only marines who have served in the first company are allowed to wear [[Power_Armour#Terminator_Armour|terminator armor]]. 

The 2nd, 3rd, 4th, and 5th Companies are Battle Companies. Guilliman's reorganisation allows companies to be composed of as many as twenty squads of five men in which there will always be least six Battle line squads, at least two Fire Support squads, and least two Close Support squads.  They train together, and when a Space Marine Company deploys as a single unit it will be one of these. 

The 6th, 7th, 8th, and 9th Companies are Reserve Companies and more specialized than the first five companies. The 6th and 7th Companies are composed entirely of Battleline squads (whose Tactical Marines also specialize in using [[Bike Squad|bikes]] and [[Land Speeder]]s, respectively), the 8th Company of Close Support squads and the 9th Company entirely of Fire Support squads. Additionally, Primaris Marines in reserve companies may also be seconded to Battle Companies as '''Vanguard Marines'''.

Originally, the 10th Company was composed entirely of [[Scout]] Marines, who were eventually promoted to other companies after a certain number of years. It's worthy of note that the 10th company was typically the largest in the chapter, containing 100 neophytes in addition to veterans seconded to the company for training. Additionally, the 10th company's 100 man limit was often uncapped so as to keep the chapter's flow of new marines steady in times of great loss. With the recent revisions to the Codex, Guilliman has ordered that all [[Primaris Marines]] train in '''Vanguard Tactics''' during their time in the Scout Company and can later revert to the squad organisation as required, whereas a regular Tactical Marine might never don his Scout uniform ever again (except in the old [[Deathwatch (RPG)|Deathwatch RPG]]). Consequently it now retains 10 squads' worth of fully initiated Vanguard Marines whose roles can be changed as needed, while the Scouts no longer seem to be counted towards the nominal 100-marine limit at all and just assigned where necessary and recruited however the Chapter deems fit. Given the [[Great Rift|current circumstances]] this is a sensible move.

There is a fair amount of leeway given to what roles the reserve companies can maintain.  The 7th company, for instance, is given the moniker of "tactical reserve."  Some chapters field these companies as bodies to replace losses from the battle companies. Some use them to train landspeeder pilots (the Codex states the entire company should be able to ride landspeeders.). Some chapters, such as the [[Salamanders]], use the 7th company to train fighter pilots for their Air Force. Others, typically those suffering from heavy losses,  use it in place of the tech auxillera for tank crews.  Still others keep weapon specialists, such as dedicated plasma-gunners, on hand to replace battle company soldiers as need demands.

===Marine roles===

Among the tenets of the Codex, Guilliman outlined the roles of various Marines to be used in Chapters. They include the following:

====Battle Line====
*'''[[Tactical Squad|Tactical]] Squad''': The backbone of a Battle Company, Tactical Marines are those who are flexible in combat, relying on both ranged weapons and melee weapons in combat. Note that due to the order of the Companies, they usually have served as both Assault and Devastator Marines, so they definitely know the basics of both, granting the majority of the chapter great theoretical tactical flexibility.
*'''[[Intercessor]] Squad''': Those Primaris Marines who are armed uniformly with some version of Bolt Rifle, either the standard version, the more mobile Auto Bolt Rifle, or the longer-ranged Stalker bolt rifle. Their role on the battlefield is to set up lines of fire and advance on and secure objectives much in a similar way to Tactical Squads; although they lack their little brothers' overall flexibility due to their exclusive use of Bolt Rifle variants, it is said that a combination of these units with other squads is invaluable to a commander. They may be equipped with [[Combi-weapon|Combi Grenade Launchers]]. The Sergeant may take Chainswords, Power Weapons and/or Hand Flamers.
*'''[[Infiltrator]] Squad:''' Recon Primaris Marines wearing a slightly lighter armament, but are expected to perform extended operations behind enemy lines. All Primaris Marines can revert to Vanguard Marines at any time, though Primaris Marines from the reserve companies often get seconded to frontline companies in this way.

====Fire Support====
*'''[[Devastator Squad]]''': Devastator Marines can be summed up in three words: Blow shit up. The purpose of the Devastator is to provide artillery strikes and heavy weapons fire in battle, and hunt tanks. Once a Scout earns his Black Carapace and Power Armor, he will be attached to a Devastator Squad, allowing him to gain battlefield experience by watching the conflict from afar with the added perk of allowing a new marine to bond with his armor while learning its strengths by lugging heavy weapons around.  Unlike [[Sisters of Battle]], the Devastator title refers to organization rather than weapon skill. Devastator squads will contain both heavy weapons and bolter marines who act as spotters and loaders; likewise, the heavy weapon marines in tactical squads are tactical marines, not devastators.
**'''Devastator [[Centurion Squad]]:''' Devastators trained to wear Centurion Warsuits, allowing them to carry considerably more firepower than any other marine short of a dreadnought. Centurion squads are organised in combat squads of three rather than five, which means that the reorganization of the codex to accommodate more variety actually means leftover soldiers can bulk up other Demi-squads without interfering with the 100 man standard.
*'''[[Hellblaster]] Squad:''' Primaris Marines who show a particular talent for marksmanship are elevated to the position of Hellblaster, which makes them a sort of elite promotion rather than Devastators who are often newbies. The reason for this is because the Plasma Incinerators they wield are very rare and difficult to maintain, and so are be entrusted to the care of a warrior who can put them to best use. Their role is to provide dedicated anti-armor firepower without sacrificing mobility in the process, and assault and heavy variants of the Plasma Incinerator also exist for greater effectiveness against massed light infantry and vehicles, respectively.
*'''[[Aggressor]] Squad:''' Primaris marines equipped with Mk X Gravis Armour, Auto Boltstorm Gauntlets and Flame Gauntlets (essentially power fists with built-in bolters or flamers, respectively). in the case of the former, they may also use shoulder-mounted grenade launchers to further supplement their firepower. Aggressors fulfill a similar role to Centurions and are also organised into combat squads of three, but are somewhat more lightly armed in exchange for superior maneuverability. Their role is to provide close-range anti-infantry fire support to an advancing force as they move in for the kill.
*'''[[Eliminator]] Squad''': Marksmen Vanguard Marines wearing stripped-down Phobos Armour, with a Shrike Pattern Bolt Sniper Rifle with special ammunition or Las-fusils for AT work. Their duty is to hunt for targets of opportunity while being extra stealthy.
*'''[[Suppressor]] Squad:''' Come with Omnis Pattern Armour, a lighter variant of Gravis Armour equipped with various jump packs, grav chutes and shock absorbers. Unlike Inceptor Marines, they aren't meant to crash onto the battlefield from low orbit and cause havoc but are instead intended to maneuver themselves into position and lay down withering fire with their Accelerator Autocannons.
*'''[[Eradicator]] Squad:''' Come with Melta Rifles for medium range anti armor support and are equipped with Gravis Armor. Can exchange their Melta Rifles for the Heavy Melta Rifle variant, and one in three per squad can carry a Multi-Melta.
*'''Heavy Intercessor Squad:''' Equipped with Gravis Armor and carry either Heavy Bolt Rifles, shorter ranged and less powerful but faster firing Hellstorm Bolt Rifles or more powerful, slower and longer ranged Executor Bolt Rifles. One in every five Heavy Intercessor can carry a corresponding Heavy Bolter variant. Standard Heavy Bolt Rifle squads carry normal Heavy Bolters, Hellstorm Bolt Rifle Squads carry Hellstorm Heavy Bolters and Executor Bolt Rifle Squads carry Executor Heavy Bolters.

====Close Support====
*'''[[Assault Squad]]''': Assault Marines are those who specialize in melee combat, using [[Chainsword|Chain]] and [[Power weapon]]s alike to fuck up the enemies of the [[Imperium of Man]]. In addition, they also usually take to the field wearing jump packs, which allows them to deepstrike onto the battlefield, move quickly from point to point, and even execute a jet-fueled charge of awesomeness into the enemy. This is the next stop in a new Marine's career when he graduates from the Devastator squads (Blood Angels start as Assault and become Devastators, a relatively common approved Codex variation; see below for details), helping to familiarize him with any weapons he hasn't used yet and putting him through the crushing psychological stress of hand-to-hand combat under something resembling optimal conditions.  Assault marines can also use bikes, attack bikes, landspeeders, drop pods, Rhinos, and Razorbacks.
**'''Assault Centurion Squad:''' Assault Marines trained to use the Centurion warsuits for siege breaking and trench clearing.
*'''[[Inceptor]] Squads:''' Primaris marines who fulfill an analogue to the Assault squad role, though their function is less about engaging the enemy at close quarters and more to act as the spearhead unit that will arrive in advance of the main force and secure the drop zone. Their Assault Bolters and Plasma Exterminators are surprisingly powerful for their size, allowing Inceptors to perform deadly hit-and-run attacks.
*'''[[Reiver]] Squad:''' Primaris specialists in shock and awe tactics, who fill a role somewhere between Assault Squad and Scouts. Their mission profile is to create confusion and terror by attacking from unexpected angles; to do this they can either infiltrate onto the battlefield or glide in silently on grav chutes. In battle, they can choose to wield either a paired combat blade and heavy bolt pistol for melee use or a bolt carbine for close-quarters firefights.
*'''[[Incursor]] Squad:''' Vanguard marines clad in lightweight Phobos Armor made for flushing out hidden positions and close combat. Their special Occulus Bolt Carbines and Multi-Spectrum Arrays allow them to detect enemies in any circumstance, while their haywire mines can cripple vehicles. Curiously, these are the only marines that seem to know how to dual-wield their knives effectively enough to be standard issue.
*'''[[Bike_Squad#Primaris_Outriders|Outrider]] Squad:''' Primaris Bikers, armed with bike-mounted frontal twin bolters, bolt pistols and astartes chainswords.
*'''Assault Intercessor Squad:''' Primaris marines equipped with Chainswords and Heavy Bolt pistols. The Sergeant may take the same weapons as an Intercessor sergeant, as well as Plasma Pistols and Thunder Hammers.

====Others====
*'''[[Scout|Scout Squad]]''': Scout Marines are Neophyte Space Marines who are charged with scouting terrain and enemy positions, in addition to demolitions and what we would today call special forces operations. A risky job, but this has the effect of ensuring that the more cautious ones survive while the reckless and foolish are weeded out.

*'''[[Veteran Squad]]''': Veteran Marines are those who have been through several centuries of combat, allowing them access to all the cool toys in the Chapter's armory. They're hopefully experienced and cool-headed enough not to, say, [[Dakka|super-glue the relic blade of the founder to the codpiece of their armor to skullfuck the enemies of mankind.]] A Chapter's first company veterans get to wear [[Terminator]] armor (the Crux Terminatus is a cross between a medal and authorization papers) but they sometimes stay with normally-sized power armor which is instead slowly turned into Artificer armor by all the bling and enhancements. Power-armored Veterans are divided into two subgroups: Vanguard (who focus on close quarters combat) and Sternguard (who focus on bolter drills and other forms of ranged warfare).

*'''[[Bladeguard Veteran]] Squad''': Veteran Primaris Marines with Storm Shields, Heavy Bolt Pistols and Master Crafted Power Swords. The Sergeant may exchange his Heavy Bolt Pistol for a Plasma Pistol or a Neo-[[Volkite]] Pistol.

The first and tenth companies '''very''' rarely take to the field as single formations; instead the veterans are seconded to other companies, often serving as commanding officers and sergeants to other squads, so as to spread their experience and skill as widely as possible. The same is also said of Scouts, who are attached to other companies as auxiliary units so that they can learn their trades alongside their more experienced brothers.  

A very common codex variant is to keep a company's veterans attached to their parent company permanently, acting as an additional squad in a company and assisting the captain and his command staff where necessary, filling the role of Champion, Standard Bearer and any other administrative positions as the Command Squad. These men are very seldom counted as part of the 100 man structure of the company and are instead counted among the command staff. More rarely the Veterans will supplant one of the tactical squads, particularly when they act autonomously from the Captain and form the line of battle, instead of as a command squad - or in an even greater deviation from the codex, are added as an extra squad that is counted amongst the company's order of battle. This organization is used by the [[Space Sharks]], [[Iron Hands]] (and most of their successors due to the ancient Clan-Company tradition), [[Iron Snakes]], [[Executioners]], and [[Dark Angels]] (and their successors, as their first and second companies are the [[Deathwing]] and [[Ravenwing]] and they have... special duties, see below and their articles) among others.

===Ranks===

The Codex Astartes formalized and simplified the ranks among the Adeptus Astartes, eliminating some ranks like "commander" while adding some more. They include:

*'''[[Chapter Master]]''': The grand poobah of the Chapter. He is the one who gives Marine companies their assignments and is under no obligation to recognize any external authority save for the [[God-Emperor of Mankind]], though most Chapter masters will recognize and honor (if not obey) the authority of the Inquisition and the Administratum. A chapter master is not merely the commander-in-chief of the chapter; he is also expected to be an administrator, a paragon of martial skill, a councilor, a tactician, a strategist and often even an admiral or a planetary governor as the chapter master will typically have ultimate authority over the chapter's homeworld (or home fleet in the case of crusading chapters). Needless to say, chapter masters are some of the most formidable individuals in the galaxy, rivaled only by the greatest heroes and monsters of other races. Some Chapters (especially the [[Iron Hands]] and most of their successors who use the Clan-Company system) don't have Chapter Masters and have the company Captains jointly rule through council, though they may elect one among their number as Chapter Master either temporarily or permanently. 
*'''[[Brother-Captain|Captain]]''': Captains are the commanders of Companies, overseeing their Marines from the front line instead of the back. Captains are usually promoted from the senior Sergeant in the Company (though with the advent of Lieutenants this might have changed). The most senior is the First Captain. Each Company Captain also holds a Chapter-level position of authority, supervising his Chapter's fleet, vehicle pool, recruits, or territory.
**The First Captain holds the title of '''Regent''' and commands the Veteran First Company as well as being the regent of the Chapter's Home World or Fleet and the heir apparent to the Chapter Master. Most likely of all the Captains to wear Terminator armour as he is leading the squads that get to have it in the first place. Some chapters have the Chapter Master be the First Captain and directly lead the First Company (found in the [[Salamanders]] and [[Crimson Fists]]).
**The Captain of the Second Company is the '''Master of the Watch'''. Charged with maintaining discipline, they serve as the prosecution during trials within the Chapter and handle other cases involving a lack in discipline but which are not quite heretical. Their main responsibility lies in the logistics of defense for the chapter's Fortress-Monastery/main base of operations. In fleet-bound chapters these responsibilities are often rolled into the title of Master of the Fleet.
**The Captain of the Third Company is the '''Master of the Arsenal'''. They oversee the Chapter's stockpile of weapons, munitions, and vehicles of war, maintaining both number and quality of such. Likely works closely alongside the Master of the Forge.
**The Captain of the Fourth Company is the '''Master of the Fleet''', charged with taking care of the Chapter's Fleet. It would seem logical that this position is more important in fleet-based Chapters as ships are even more key to the Chapter's function. The Master of the Fleet can give up his duty and simply be Fourth Captain if one more qualified than them is available for the duty of naval command (all captains can theoretically do this, but the Master of the Fleet is where this exception is most frequently found). Some Chapters have dedicated separate Masters of the Fleet and give the Fourth Company Captain a different role entirely.
**The Captain of the Fifth Company is the '''Master of the Marches'''. They have the duty of overseeing the Chapter's deployment and fighting strength; when a Chapter is rebuilding, they have the final say when the Chapter is ready. Their duties require an immense amount of time and effort; it is not uncommon for a Master of the Marches to spend all of his time on incoming data, which does not seem like the thing a seven foot superhuman should spend his time on. The Chapter Masters probably don't trust a newbie or mortal to handle something this important.
**The Captain of the Sixth Company is the '''Master of the Rites'''. They perform and oversee the rites, rituals and other formal occasions inherent to the Chapter; as such their duty (and the size of it) differs between the various Chapters. In many cases they work closely with the Chapter's Chaplains. The precise differences between Master of Rites and the Master of Sanctity vary greatly between chapters, generally with both holding special significance under different spheres.
**The Captain of the Seventh Company is the '''Chief Victualler'''. They are tasked with maintaining the logistics within the Chapter and with outside forces, ensuring supplies that the Chapter cannot make for itself are procured and that there is enough raw material for the things the Chapter can produce. They also make sure that the various ships and bases of the Chapter have ample supplies. Synonymous with Quartermaster.
**The Captain of the Eight Company is the '''Lord Executioner'''. Unlike his brethren, the Lord Executioner serves as a weapon for the Chapter, to be bloody in battle and destroy the Chapter's enemies in close range.
**The Captain of the Ninth Company is the '''Master of Relics'''. Their duties are twofold: to tend to the various relics that the Chapter has and to engage in long-ranged warfare both in sieges and firefights. Rumor that this duty also includes warding any and all Blood Ravens from the armory is unconfirmed.
**The Captain of the Tenth Company is the '''Master of the Recruits'''. They oversee the recruiting, indoctrination, training and deployment of the Chapter's Neophytes and Scouts.
**It should be noted that Chapters tend to have different roles for their Captains. The most common variant is among the [[Dark Angels]] and their successors within the Unforgiven having [[Deathwing]] and [[Ravenwing]] First and Second Companies with different roles for the Captains of those companies. Another common variant is to have one or more Captains to be designated as '''Siege Captain''', specializing in taking and holding fortifications. This may be in addition or in full replacement of their normal roles as captain.

*'''Lieutenant:''' with the unveiling of Cawl's new Primaris Marines came a slight reorganisation of codex companies and delegation of officers duties. Each space marine company now has two lieutenants subservient to its captain, though their exact duties can vary from chapter to chapter; for example, Salamanders lieutenants are [[This Guy|ceremonial bodyguards]] for their Captain, whilst Iron Hands lieutenants are [[That Guy|naysmiths]] charged with arguing against their Captain's battle plans in order to ensure his logic is free from human error. Their main function is to act as an executive to their Captain and take command of the demi-companies when the company splits (one per demi-company), allowing specialist officers such as Chaplains and Librarians to actually focus on their roles rather than taking command themselves, which makes sense considering specialist officers trained for a particular duty may be no more qualified to command than any other battle brother.
**As with Captains, there is no actual requirement for Lieutenants to be Primaris Marines, and as it stands, regular Astartes lieutenants are more flexible thanks to the wider range of compatible wargear.
*'''Force Commander''': Not a rank but a title given to the commander of a task force, either given if more than one company is fighting at the same time in which case it would be the senior captain or if the company has to split up and a junior officer such as a lieutenant takes command of forces aside from his own captain.

*'''[[Brother-Sergeant|Sergeant]]''': Sergeants lead squads of four to nine other Marines depending on the influx of recruits. There are approximately ten sergeants per Codex-approved Company. Often the most senior sergeant will be the commander of a company's "First Squad" ''(usually a Tactical Squad)'' and will likely be next in line for a promotion if the Captain is ever slain, but not always. Members of the Captain's Command Squad may also be Sergeants who get additional duties as required.

*'''[[Veteran Squad|Veteran-Sergeant]]''': Not a "rank" exactly, but more of a recognition of status for those who have been members of a Chapter's First Company; quite frequently these guys get redistributed back to the lower companies to act as squad leaders where their experience will do some good, hence "Veteran Sergeant". These guys will usually get to wear the "Crux Terminatus" even when in power armour to represent the fact that they have earned the right to use Terminator Armour. Note that Veteran Sergeants can serve in the ranks of the Scouts, Devastators, and Assault Marines despite being technically overqualified, in each case helping the new recruits to adapt to Chapter life. In old 3rd Edition rules you could get Captains without terminator honours, which implied that they never passed through the first company but still got command; nowadays a Captain is just one thing. It's also important to remember that the number of Veterans in a Chapter is not limited by the Codex.

*'''Champion''': Champion is actually a number of positions within a chapter, with each company having a champion, the chapter as a whole having a champion, and a champion being drawn from within the ranks of the honour guard to serve as the personal champion of the chapter master (though these last two positions are often held by the same marine). A champion is theoretically the best close quarters fighter in a company, charged with protection of the Captain from all threats. Given that your average Captain is a badass in power armor this may seem redundant, but it's supposed to allow him to focus on coordinating the battle while the Champion tears up anyone who tries to interrupt. One of the biggest dissonances between the crunch and fluff is manifested with the champions: on the tabletop officers are almost universally more formidable than the champions that are supposedly there to protect them. In an ideal scenario, the Chapter has one champion for each Company, one Honour Guard Champion, one Chapter Master's Personal Champion and one Chapter Champion (the Honour Guard Champion and Chapter Master's Champion titles are frequently held concurrently by one Marine) giving a total of 12 or 13 champions for a full strength Chapter. 

*'''[[Honour Guard]]''': A veteran's veteran, assumed to be the best of the best. These guys get bunched together and given some of the best gear available to the chapter. The fluff tells us that these guys are peers of Captains in terms of battlefield experience but do not have the command rank to actually issue any orders, though when Honour Guard speak up it's advised that the officers nearby listen carefully. Thankfully the tabletop game is balanced not to give a whole squad full of Captain-equivalent soldiers. As noted above, one of the Honour Guard is the Honour Guard Champion.

*'''Standard Bearer''': The Company Standard Bearer, given the title of '''Ancient''' (the old term for Ensign, who was the traditional standard bearer), is charged with carrying and protecting the Company Standard. Also frequently joins the Command Squad. Should a Company Standard Bearer drop the banner and let it fall to the ground, he will essentially forfeit his honor. If the Standard Bearer should be killed and the banner stolen, the entire Company will be dishonored until the banner is reclaimed. Which means that if you steal a Company Standard, you now have nearly one hundred Space Marines who were just trying to kill you, but now you had to go and make it personal. The most elite of these is the Chapter Standard Bearer (often a member of the Honour Guard, but not necessarily), who carries the Chapter banner in war. If the Chapter Ancient isn't among the Honour Guard, then the Honour Guard will have its own Ancient as well. Primaris Bladeguard have [[Primaris Ancient|Bladeguard Ancients]].

===Other Departments===
Outside of the above mentioned battle ranks, there are other positions within a Chapter:

====Librarium====
A chapter may have any number of [[Librarian]]s, with no Codex-mandated minimum or maximum. The fact that psykers, let alone Astartes psykers, are rare makes the position self-limiting. Can use the standardized Librarian Discipline, Chapter specific disciplines or generic [[Psychic Disciplines]] like Biomancy, Pyromancy, Telekinesis, Telepathy, Technomancy or Divination to name a few.
*'''Chief Librarian''': The head of the Librarium, who assigns [[Librarian]]s to assist in battlefield communications. He is also tasked to determine whether or not his battle-brothers are tainted by [[Chaos]].
*'''Epistolary:''' The highest rank below Chief Librarian, Epistolaries serve as the main communication aides on the battlefield.
*'''Codicier:''' Mid-level Librarians who evaluate reports from campaigns and document them in their Librariums. 
*'''Lexicanum:''' Entry-level Librarians responsible for compiling battlefield reports for the Codiciers. 
*'''Acolytum:''' Neophytes who have been identified as psykers.
*'''[[Vanguard Librarian]]:''' Primaris Librarian assigned to Vanguard duty. Trained in the special Obscuration discipline.

====Apothecarion====
A chapter may have any number of apothecaries, although the Codex mandates at least 11 (one per Company, plus the Chief Apothecary).

*'''Master of the Apothecarion''': The head of the Apothecarion, who assigns an [[Apothecary]] to each Company. The Apothecarion in turn also takes care of the [[gene-seed]] that Chapters place such holy emphasis on, for good reason: no gene-seed = no new recruits.
*'''[[Apothecary]]''': Responsible for medical care, biological and genetic research, and the critically important harvesting of gene-seed from Battle Brothers and the cultivation of said gene-seed.
*'''[[Primaris_Apothecary#Helix_Adept|Helix Adept]]:''' Apprentice Primaris Apothecaries assigned to [[Infiltrator]] squads.

====The Chaplaincy/Reclusium====
A chapter may have any number of chaplains, although the Codex mandates at ''least'' 11 or 12 if fully staffed (One per Company, plus the Reclusiarch/Master of Sanctity).
*'''Master of Sanctity''': The head of the Chaplaincy and spiritual leader of the Chapter. He assigns [[Chaplain]]s to the Companies to oversee the spiritual health of the Chapter. This position is often but not always held by the chapter's Reclusiarch. Though it might be tempting to compare them to warrior bishops, they're actually atheists (save some Chapters closely aligned to the [[Ecclesiarchy]] or the [[Mechanicus]]), seeing the Emperor as an honored predecessor and the epitome of humanity but not a god. 
*'''Reclusiarch''': The Chaplain who oversees the Chapter's Reclusiam (where they keep the relics and other secret historical stuff). Often the job gets rolled up into the Master of Sanctity's job description (particularly if the Chapter is relatively young and has not accrued entire millennia worth of trinkets). It's uncertain what interaction (if any) they have with the Master of Relics; it is quite possible that a Chaplain receives the role if that Captain of the 9th company gets a different position. It is possible that the Reclusiarch looks after the more "holy" and historically significant relics, distributing some of them to Chaplains to carry in battle, while the Master of Relics okays the deployment of precious but combat-worthy stuff like ancient marks of power armour or Heresy-era tanks (Master of the Forge is technically a specialist position, not an authoritative one).
*'''[[Chaplain]]''': Ministers to the psychological stability of their brothers, inspiring them and allied forces in battle and watching for Chaos corruption.
*'''[[Judiciar]]''': Primaris Chaplains in training equipped with Executioner Blades and Tempormortis temporal distortion devices, charged with enforcing the Chapter Master's will.

====Armoury/Armorium====
A Chapter's armoury consists of any number of [[Techmarine]]s and dedicated vehicle operators who do not formally get assigned to any Company.
*'''Master of the Forge''': The head of the Armoury, who assigns [[Techmarine]]s to oversee maintenance of the machine-spirits of the chapter's wargear and motor pool. Their position often overlaps to some degree with the Chapter's Reclusiarch, given that both are responsible for keeping the chapter's relics in good condition; many artifacts will fall under both of their duties. Given that their religious zeal is tempered by the practical mindset of a space marine, Masters of the Forge are some of the only engineers in the galaxy that are actually still innovating to any degree, which really shows when you compare the armories of the modern space marine chapters with their traitorous counterparts. 
*'''[[Techmarine]]''': As with the Apothecaries, one per company and the Master of the Forge plus others is a frequent arrangement; otherwise they are deployed as needed to operate advanced war gear or lend technical expertise at battle. When not in the field they repair or produce arms, equipment, vehicles and other supplies along with Chapter Serf Artificers and any Tech Priests assigned to the Chapter.
*All Space Marines are required to familiarise themselves with operation of Rhino tanks at the very least as part of their standard training.
**Drivers of the armoury vehicles are referred to as '''Custodians''' (unrelated to the [[Adeptus Custodes]]), many of whom are assigned when necessary from the squads of the 6th & 7th reserve companies. They are expected to continue their development through the companies and learn ''every'' aspect of war so that vehicle commanders better anticipate the roles of Tactical/Assault/Devastator and provide battlefield support without even being requested - unless they get assigned to the armoury on a more permanent basis, such as being trained to operate larger, more precious vehicles and/or specialising in armoured operations.
**Battlefield support vehicles tend not to be assigned permanent crews but are manned by individuals capable of operating a number of chapter vehicles, helped in part to the ubiquity of the Rhino chassis and the standard training.
*Dreadnoughts are typically assigned back to their original companies and appear sporadically across a chapter's roster, though some chapters assign Dreadnoughts to their own formations instead. The technology to build even the most basic dreadnought is rare and time-consuming even for master artificers, so the number is limited; also the frequency of wakefulness decreases over time and they get used less and less.

====The Fleet====
A chapter is allowed a fleet of as many ships as it can get together, and may assign Marines to these ships as permanent staff in a similar fashion to the Armoury, although the Codex is significantly more flexible on Fleet staff. A chapter can be Codex-compliant without any Marines in their Fleet at all.  Ship designations made for Space Marines have a fairly narrow band of marine transport capacity - one to three companies' worth - which does not change significantly between chapters. Therefore while a chapter could theoretically muster a fleet of any size, the practical and political restraints limit a chapter fleet's size. At the top end, the best is a [[Battle Barge]] for each company, another Battle Barge for a flagship and accompanying [[Strike Cruiser]]s, [[Adeptus Astartes Light Cruiser|Light Cruisers]] and [[Adeptus Astartes Escort|Escort]]s, plus whatever orbital defenses of the homeworld and the system fleet and maybe one or two mobile stations. This is stretching it for most chapters, though ancient and politically secure can have more than this and some chapters have different classes of ship as well. The Navy frowns upon Marines having too many [[Lance Weapon|Lance]]-equipped ships in particular. Fleet based Chapters obviously have more than usual, and one powerful vessel, possibly even a Warp-capable Star Fort, serves as the Fortress-Monastery.

*'''Master of the Fleet''': Often the Captain of the 4th company gets this position by default, but as mentioned above in the entry for Fourth Captain it's [[Uriel Ventris|not unheard of for a Captain to step down]] from the position if someone else would be better suited to the role: that person is titled "Lord Admiral" and gets command over the Chapter's fleet assets. It is perfectly reasonable that the Lord Admiral holds a battlefield rank of Battle-Brother or Sergeant, making him probably temporary until the Captain or his replacement wants the job back. As mentioned above, some Chapters (especially fleet-based ones) have this post be straight-up separate from the role of Fourth Company captain and have a dedicated full-time Marine as Master of the Fleet in the Chapter Council while the Fourth Captain gets different special roles.
*'''Lieutenant Commander''': In the days of the Great Crusade, these individuals commanded battalions of five companies, outranking Captains and subservient to Chapter Masters. We know of [[Marines Errant|only one example]] of this rank though it is uncertain whether the title holds the same authority as before. From what we know it now applies to the commander of a vessel, which makes sense since most Space Marine chapters have more ships than Captains, so ''somebody'' has to get the job of commanding them. Often assumed to be just a techmarine or sergeant of whichever squad gets attached to that vessel, or more likely a badass high ranking [[Chapter Serf]] who doesn't need to be superhuman to understand how spaceships operate. 
**With the advent of the company rank of Lieutenant, it is uncertain as to how the Lieutenant Commander actually fits in the new command structure. Is it a superior form of Lieutenant with new duties (which is what the rank itself implies) or is it a Lieutenant who has been officially combined with the Force Commander role (see above) and has his own units set aside from his company that he commands on a full time basis? More likely, considering that Space Marines tend to hold to an army chain of command rather than a naval hierarchy, the rank is probably an honorific title that stands alongside their company rank as with the Lord Admiral. It is also quite possible this is now the same as a old ''naval'' Lieutenant Commander, which was a ''Lieutenant'' serving as the ''Commander'' of a vessel.

==Codex Skub==
In case you haven't picked up on it yet, the Codex is rather controversial for a number of reasons. First off, and perhaps most significantly, is the fact that even GW's own writers don't agree on what the codex is. [[Dan Abnett|Saint Abnett]] views it as a book of tips and strategies, comparable to ''The Art of War''. Graham McNeill (the guy who wrote the Ultramarines Omnibus) sees it as a comprehensive but inflexible guide to strategy, organization, and conduct. Matt Ward quite famously sees it as a literal Space Marine Bible, a holy book that all marines follow to the letter. Like a lot of GW lore, the canon is up in the air, and as such it's open to interpretation. Many writers are clearly very critical of the Codex, and portray it as antiquated and damaging, whereas others portray it as comprehensive and useful but increasingly antiquated. Also there's Ward, but let's not talk about him. Which version is true? Yes. 

It's also worthy of note that many people within the Ultramarines take the Codex with a grain of salt. [[Captain Titus]], [[Uriel Ventris]], even [[Marneus Calgar]] and the freaking [[Roboute Guilliman|primarch himself]] have all been critical of the codex at various times, or rather been critical of people's reception of it. All of these people see the codex as useful and important, but take issue with people, Ultramarines or otherwise, that see it as a holy book that contains everything you need to know. Perhaps Guilliman himself put it best, saying, ''"[My teachings] are yet flawed. No one, not even one such as I, can anticipate every possible outcome of battle. My words are not some holy writ that must be obeyed. There must always be room for personal initiative on the battlefield. You and I both know how one spark of heroism can turn the tide of battle. That knowledge and personal experience can only be earned in blood, and the leader in the field must always be the ultimate arbiter of what course of action should be followed."'' As the opening quote implies, Captain Titus is also quite critical of Leandros's interpretation of the codex, pointing out that personal initiative is just as important as adhering to the codex. Then again, Titus is also quite clearly a company champion who got mistaken for a captain, what with his disregard for tactics in favor of glorious melee, so maybe we should just ignore what he thinks. 

Ultimately, your own take on the codex is going to depend on a number of things, including whose canon you believe, you opinion of the Legions, your opinion of Guilliman, and a dozen other things. Don't let yourself get pulled in by the fanboys saying the Codex is the perfect guide to everything, and conversely don't listen to the idiots who say the Codex is only useful as toilet paper.

=="Codex" Chapters with doctrinal variations==
More commonly, are those chapters which follow the codex at an organisational level, but disregard certain tactical aspects contained within, most likely because they have their own modus-operandi that they have a preference for, or because they create their own unique tactics that had never been considered.

'''[[Aurora Chapter]]'''
*Follows the Codex Astartes, yet has a large number of vehicles.
*They have a lot of vehicles.
*For a 1000 man sized Chapter, they have a lot of tanks.
*Of all the Codex Chapters they have the most tanks.
*Their armored spearhead attacks are pretty devastating.

'''[[Charnel Guard]]'''
*Cannot say too much about those guys since they are very secretive, thus their organisation and structure are completely unknown.
*Are confirmed to be Blood Angels successors, yet as said before, they are totally unknown from a organisational and structural P.O.V.
*Have a lot of Great Crusade and Horus Heresy Era stuff, including a Fellblade.

'''[[Crimson Fists]]'''
*More tactically oriented [[Imperial Fists]].
*Actually do follow the Codex more closely than other Sons of Dorn (but not that much like the Hammers of Dorn).
*At the time of their founding, they were known to be the most level-headed members of the Imperial Fists Legion, therefore took in the Codex much faster and easier.
*Only deviation is the existence of a Crusader Company that is a 1st Company that has 128 Veterans. A result of an event where they were reduced to 128 members during the Crusade of Righteous Liberation.
**Their First Company is also led by their Chapter Master, though this is an occasional variant rather than uniquely Crimson Fist.
*Due to the whole situation with Rynn's World, the Chapter became very capable at fighting [[Orks]].

'''[[Emperor's Shadows]]'''
*Iron Hands Successors that follow the Codex rather than the Clan-Company variant.
*Put more emphasis on projectile weapons (like Bolter Weapons) and Dreadnoughts.

'''[[Hammers of Dorn]]'''
*Follow the Codex to the letter, yet do put more emphasis on heavy weapons and overwhelming firepower.
*No really, they follow the ABSOLUTE LETTER of the codex.
*Not even the [[Ultramarines]](Famous for having the primarch that wrote the damn thing) follow the codex more rigidly than them. 
*They probably actually read the Codex from cover to cover.

'''[[Hawk Lords]]'''
*Codex compliant, yet put large emphasis on flyers.

'''[[Minotaurs]]'''
*Instead of sending out a single company, the Minotaurs utilize mob and berserker tactics along with sending out all ten of their companies to utterly overwhelm and crush their foes.

'''[[Raptors]]'''
*[[Reasonable Marines|Camouflage Power Armour]]. Technically this IS in the codex, but they're the [[Derp|only space marine chapter out of literally thousands]] that actually bothers to do it. They're also sneeki beekies, just like their Raven Guard progenitors.

'''[[Raven Guard]] and Sucessors'''
*Sneeki Cheeki [[beakie|Beekies]]. While they do follow the codex, their chapter is renowned for its skill with [[Reasonable Marines|stealth tactics and guerilla warfare]]. It also made extensive use of mutants (during the [[Horus Heresy]]) due to their situation after the Drop Site Massacre.

'''[[Space Sharks|Space Sharks/Carcharodons]]'''
*Greater emphasis on infantry and terror tactics.
*Will sneak up as close as possible to the enemy to later tear them a new one in close combat while berserking.
*May be organisationally non compliant as well, but they are quite tight lipped about it.
*Like the Iron Hands and Dark Angels, they keep veterans in their battle companies to maintain coherency within the companies.

'''[[Storm Giants]]'''
*Codex compliant, but utilize armoured assaults, Drop Pod strikes, and heavily use Scouts to get intel before ruining someone's day.
*Due to their heavy use of Scouts, they have a larger than average 10th Company.

'''[[White Scars]] and some Successors'''
*Disproportionate emphasis put on bikes and speeders compared to heavy vehicles, still adhering to codex formation however.
*Disfavor Dreadnoughts as they think <strike>they can't condemn their brothers to such a slow existence</strike> it is dishonourable to deny a warrior his death.

==Chapters with differences in formations or composition==
Some chapters have taken the idea of a "Chapter" and tweaked it with their own unique spin on its organization, either by adding units or ranks that aren't found anywhere else or having their own composition of companies that doesn't fit with the approved codex model. In some cases they may ignore the codex altogether and do their own thing.

'''[[Black Dragons]]'''
*Dragon Claw squads, made up of mutants who make use of adamantium-coated wrist blades.

'''[[Blood Ravens]]'''
*'''Pre-Aurelian Crusade''':
**Usually, the Chapter Master was the Chief Librarian too, like [[Azariah Kyras]]. This tradition of Chapter Master/Librarian combo started with Great Father Azariah Vidya (as in Vidya Games or the Indian term for knowledge, science, scholarship, learning etc.), who the chapter believes was their founding Chapter Master (officially he was, but given they are Thousand Sons loyalists who don't know their heritage someone else probably founded them and were censored willingly). This would backfire dearly when Kyras turned out to be a heretic.
**Their gene seed causes them to have an above average number of Librarians, so many they can field two whole squads of them in the First Company. Librarians are so recurrent among Blood Ravens that it's not uncommon for one to even be a Captain (can you actually name one though?).
**Actually Codex Compliant in structure, yet utilize their Librarians to scry and predict the movements of their enemies (so their Scouts are Librarians too?) and use the intel to formulate a counter strategy (because they appeared in [[Dawn of War]], their way of war is an emulation of how RTS gamers play when they are serious).
**Non-standard patterns of [[Apollo_Diomedes|speech]], incidents of [[Blood_Ravens_Force_Commander|hairesy]], compulsive [[Blood_Ravens#Bloody_Magpies|kleptomania]] and emphasis on [[Indrick_Boreale|devastating, defensive deep-strikes]].
*'''Post-Aurelian Crusade''': 
**With [[Gabriel Angelos]], a non-psyker, taking the position of Chapter Master and separating the Chapter Master and Chief Librarian (currently [[Jonah Orion]]) positions, they returned to a more codex-compliant organization, albeit severely undermanned pre-[[Indomitus Crusade]].

'''[[Blood Angels]] and Successors (collectively "The Chapters of the Blood" or just "The Blood")'''
*[[Scout]]s graduate to [[Assault Squad]]s rather than to Devastator squads to work out Red Thirst related anger issues.
*The use of [[Heresy|non-standard tech]], like Baal Predators, Furioso and [[Dreadnought#Chapter_Specific_Dreads|Librarian Dreadnoughts]].
*[[Sanguinary Priest]]s (Apothecaries) make up part of the chapter priesthood equivalent to Chaplains, who are busy tending to...
*...The [[Death Company]].

'''[[Dark Angels]] and Successors (collectively "The Unforgiven")'''
*The [[Deathwing]] & [[Ravenwing]] instead of First and Second companies. As of the start of the [[Indomitus Crusade]] (8th edition), this modification has been officially approved by Guilliman, ostensibly on account of their proven effectiveness. 
*Inner Circle in place of the usual chapter command structure.
*Chaplains taking the additional role of [[Chaplain#Dark_Angels_Interrogator-Chaplain|Interrogators]].
*Battle Companies incorporate an additional squad of [[Veteran Squad|veteran marines]] picked from within the company as the Deathwing does not directly take promising veterans as other First Companies would.
*Some nifty STCs that they do not share with anybody apart from their own successors (The Mortis Dreads and Land Raider Ares).
*Handful of successors not in the Unforgiven due to diplomatic fractures, but retain standard practices.

'''[[Executioners]]'''
*Disregard many of the Codex's rules and trappings but follow the ten company outline.
*Choose to go into close combat with the enemy while heavily preferring Land Speeders over Bikes.
*Each company has three [[Chaplain|Death Speakers]].
*Battle Companies have only one Devastator Squad each, but can field their own Veteran Squads.

'''[[Exorcists]]'''
*Have two additional scout companies to account for the high attrition rate amongst recruits.
*...said attrition rate being caused by subjecting recruits to daemonic possession.

'''[[Imperial Fists]]'''
*Apparently picked up a loophole from the Blood Angels and have their scouts immediately go to the Assault reserve company to work out their unbridled aggression before becoming Fire Support.

'''[[Iron Hands]] and Most Successors'''
*Have a Chapter Council instead of a fixed [[Chapter Master]], though a leader may be nominated.
*Chaplain Techmarines, aka "[[Chaplain#Iron_Hands_Iron_Father|Iron Fathers]]".
**The current leader is thus a Chapter Master Chaplain Techmarine. And people say the Blood Ravens are the crazy ones.
*Each Clan Company has its own armoury, rather than a single armoury for the whole chapter including relics for individual companies, but the Master of the Forge (effectively also the Master of Sanctity and Reclusiarch) still has the very very important stuff.
*Terminator Armour was distributed to squad sergeants instead of being reserved only for the First company. It's uncertain if this still exists as of 8E.
*Pre-6th Edition fluff indicated that individual companies (clans) had their own veterans and recruits; newer fluff put them more in line with the Codex on the surface.

'''[[Iron Snakes]]'''
*Instead of having five regular battle companies and five reserve companies, the Iron Snakes have ten battle companies with an equal number of veterans, regulars and neophytes for perfect balance.
*Each squad has an Apothecary, personal Squad Standard Bearer and a number of specialists of their own.

'''[[Red Scorpions]]'''
*Apothecaries act in squad command roles instead of sergeants.
*Functionally the opposite of the Raptors, the Red Scorpions ignore all of the codex's teachings on stealth.

'''[[Salamanders]]'''
*Have seven oversized companies instead of ten, but otherwise broadly conform to the codex.
**Their First Company is also presided over by the Chapter Master
*Have three Masters of the Forge, usually tending to more specialized matters since most battle-brothers can maintain their own wargear.

'''[[Silver Skulls]]'''
*Champion Librarian rank of Prognosticator, who specialize in divination and omen reading. The entire chapter has been known to refuse deployment if a single Prognosticator reads a single bad omen.
*Non-psyker elite veterans, the Talriktug, are considered second to Prognosticators despite the latter's specialist status and the formers presence in the first company.
*9th Company serves as a designated siege specialist company is counted amongst the Battle Companies rather than the Reserve Companies. The 9th Captain is referred to as the Siege Captain.

'''[[Star Phantoms]]'''
*Each battle company takes a [[Devastator Squad]] over a [[Tactical Squad]], leaving five Tactical and three Devastators squads in each.
*The chapter is never at full strength, seldom even at half, but maintains weapons as though they were. Their "tactical" reserve companies can fill in for full devastator squads, if needed.

'''[[Storm Wardens]]'''
*Tempest Blades being a non-codex formation.
*Heavy emphasis on mechanized warfare and mano-a-mano honorable duels to the death.

'''[[Ultramarines]]'''
*Tyrannic War Veterans are a non-codex formation.
*Originally, Guilliman deliberately gave himself an 11th company in contravention of his own rules for the sole purpose of guarding the [[Imperium Secundus|Pharos device]] in the aftermath of the Battle of Sotha during the heresy. This company got [[Scythes of the Emperor|rolled into its own chapter]] while the Adeptus Terra were doing their audits for an unanticipated Third Founding.
*The Ultramarines still have an [[Ultramarines Honour Company|"apparent" 11th company]] that guards the Eye of Terror, made up of volunteer squads donated from their successors but all wearing Ultramarine uniforms.
*After Guilliman's return, he appointed Decimus Felix as an 11th captain/equerry (no particular company assigned at this time). The break with the codex was enough to give Felix cause for concern. Later, Guilliman appointed him Tetrarch and gave him authority over Ultramar's Eastern expanses.
*[[Cato Sicarius]] is still the 11th (12th/13th?) Captain. He now commands the [[Victrix Guard]], which is a new formation of Veterans who act as Guilliman's bodyguards and envoys.
*There is also Captain Demeter and the Fulminata, which are a Demi-Company outside the main companies.

'''[[White Consuls]]'''
*Have [[Alpharius|two Chapter Masters]] instead of one, due their situation as one of the [[Astartes Praeses]] making the Chapter deem it necessary to have one lead the Cadian Gate garrison and the other those forces in other Imperial Warzones.

==Non-Codex Chapters==
As mentioned, there are many chapters in the Imperium and very few of them follow the codex absolutely to the letter. Many chapters have their own preferred mode of warfare based upon their experiences, supplies and dispositions, and they generate their own interpretations and deviations from the codex. Here follows a comparative listing of those chapters and the way in which they differ from what the codex actually prescribes.

'''[[Astral Claws]]'''
*'''Pre-[[Red Corsairs]] Times''': Before [[Lugft Huron]] went pants-on-heads retarded, the Chapter was known for being exceptionally stubborn with skilled Bikers and favoring lightning strikes and boarding actions while still following the Codex.
*'''[[Badab War]] Times''': 
**Due to Huron's pants-on-heads retarded thinking, the Chapter seized the Badab Sector's industry and made it so that Bolter rounds and Rhinos were mass-produced to the point of being expendable, not to mention having a larger-than-standard number of marines due to them purposefully not paying their geneseed tithe and the absorption of the survivors of the Tiger Claws, their successor chapter, after their last fleet went MIA following devastating casualties. 
**Emergence of specialized units (such as the hated Corpse-Takers) and human Auxilia. Squads larger due to aforementioned not paying of the geneseed tithe.
**Obviously, after the Badab War was lost, the survivors gave up even lip service and became a Chaos Warband.

'''[[Black Templars]]'''
*Has a liberal interpretation of the codex's fleet-based/crusade chapter rules (having more than 1,000 marines to quickly replenish losses). To the Templars, this meant as many marines as they want (but usually no more than a thousand on the ground in any one place due to obvious reasons). The actual number hovers around several thousand divided into several crusades. Technically they are still compliant as the 1000 Astartes rule only applies when not on crusade, and the Templars are always crusading.
*No Scout company, instead recruits are apprenticed to fully fledged battle-brothers, aka "Crusader squads".
*No Librarians, though some theories state that this may be due to a gene seed problem caused by the defeat of the Xenos Psyker known as the Cacodominus (see their main article for more information).
*Doctrinal emphasis on close quarters combat.
**Abundance of previously unsanctioned Land Raider "Crusader"s to deliver said Crusader squads to CQC. See the trend here?
*May or may not deify the Emperor. The canon is kind of up in the air right now.
**The position of "Emperor's Champion", a Chapter Champion-esque title but of religious significance.

'''[[Grey Knights]]'''
*Due to their unique training and equipment (not to mention the [[Chaos|intimidatingly]] [[Chaos Space Marines|insane]] [[Daemon|shit]] they have to deal with), the Codex would actually hamper them instead if they were subject to it.
*All psyker Chapter of Demon hunting marines. Nuff said.
*The infamous [[Dreadknight]].
*The [[Purifier]]s are a separate force separate from the rest of the chapter, though able to be seconded when needed.
*There are no scout companies or equivalents (they have the Ordo Malleus to do their recon work for them). An aspirant who makes it past training is immediately promoted to the role of Battle Brother.
**Similarly, the process of earning the right to don Terminator Armour is a much shorter journey, since it is not allotted exclusively to the First Company.
**That said, there is a sort of system of progression throughout each of the eight Brotherhoods (each essentially a company and representative of the eight founders of the chapter in the original Knights Errant of [[Malcador the Sigillite]]) and the elite [[Purifier]] and [[Grey Knight Paladin|Paladin]] Brotherhoods.
*Companies have both a Captain and a Grand Master.
*Company Champion is renamed Brotherhood Champion due to obvious reasons.
*Chapter frequently operates with individual squads due to that being enough for most cases, coordinated by the Grand Masters and the Captains taking the best squad of the individual Brotherhood for difficult missions not needing an entire Brotherhood.
*Chapter Master renamed Supreme Grand Master.
*Do not have any artillery weapons like Whirlwind Artillery Tanks or lack of certain vehicles other Chapters have.

'''[[Legion of the Damned]]'''
*Previously Codex-adherent [[Fire Hawks]] (maybe, now it's uncertain), now a horde of angry hellfire powered, space/time/dimension travelling, [[AWESOME|spectrerevenantdemonspacemarines]].
*Utilize more powerful but unstable early versions of existing Imperial Weapons like early Horus Heresy Era Plasma Weapons. 

'''[[Space Wolves]]'''
*Ignore the organizational parts of the codex outright. Go [[Space Wolves|their page]] to find out how they are organized.
*Simply put, [[Leman Russ]] wanted them to be forged in his vision instead of Roboute Guilliman's, and Guilliman gave him permission to do so (or rather, didn't interfere). 
*They do however take some useful tactics from the codex because they like them, and see them as just that: useful tactics, and nothing more.
*Fenrisian Wolves/Thunderwolves used by the Chapter. This may or may not be heresy. 
*Have more than a thousand marines, though not that much as the Black Templars. If anything, its just a few more hundred.
*Threw the typical training process out the window because of the Canis Helix.
*A newly trained initiate is thrown into their assault companies (called "Blood Claws") to allow them to express and better control their savage nature.
*They do have actual Scouts Squads but these are exclusively made up of veteran marines. These Wolf Scouts are selected due to being both experienced and, which is most important, cool-headed (though also because they are lone wolves)- something the Blood Claws are NOT.
*Tactical marines are known as "Grey Hunters"
*Their Devastators (called "Long Fangs") aren't an immediate position but reserved for the most battle-hardened veterans who have proven themselves capable enough of being entrusted with the ownership and handling of the chapter's heavy weaponry.
*In the previous editions, they had access to Leman Russ tanks (since the tank was named after their Primarch).
*Wolf Priests combine both Chaplain and Apothecary roles.
*Techmarines renamed Iron Priests.
*No Librarians, but Rune Priests, who are totally 100% not psykers, honest.
*Their Scouts are [[Ork Kommando|<strike>quiet psychopaths</strike> veteran loners]]

The [[Deathwatch]] also count as a unique organization, being made up of several thousand Marines seconded from other chapters and under special anti-Xenos duties across the galaxy, though technically they aren't a Chapter.

==Purpose for Gamers==

Of course, there's a reason [[Games Workshop]] included the Codex Astartes in their fluff (long before Matt Ward came along, by the way); basically it makes it easier for players to invent their own Chapters.  

Players who just have an idea for a cool color scheme or name but don't want to put any effort into making up a whole organizational layout can just make a Chapter that rigidly follows the Codex like the [[Ultramarines]]. Those who want to have one or two unique organizational or tactical features can make a Chapter that generally follows the Codex but has some variances, like... well, most of them (see above). And players that want to make up entirely independent structures themselves can make Chapters that ignore the Codex entirely, like the [[Space Wolves]] or the [[Black Templars]].

This means that [[Matt Ward]]'s Codex worship isn't just lame but actually bad for GW's business. By telling players that only Codex Chapters are any good, he's discouraging players with their own ideas from investing in models, paints, tournaments, and maybe even later editions of the game. Truly, there is no end to his failure.

{{Marines-Forces}}