[[Image:SMOrg9th.jpg|thumb|right|Organization Organisation of a Codex-Compliant Space Marine [[Chapter]] since the introduction of [[Primaris Space Marines]]{{Fn|20a}}]]

The Codex Astartes was a code developed by Guilliman. This tome would contain everything a member of the Astartes would need to know to function. From recruitment to organization organisation to tactics and beyond the Codex Astartes became a sacred text to the majority of the Chapters.{{Fn|10}} One of the most significant changes under the new Codex was the newly founded Chapters. Where the Legions could number more than 10,000 strong the Chapters would be limited to about a thousand. Each original Legion would be divided as many times as needed into successor Chapters. This division would come to be called the [[Second Founding]] seven years after the Horus Heresy{{Fn|11b}}, in 021.[[M31]]. The remaining thousand bodies in the original Legion would also survive as a new Chapter of the same name. While these newly created Chapters claimed their founders origins, such as their Primarch, they would also come to develop their own culture and customs.{{Fn|25a}}

===DeviationsRecent Reformation===SecretlyAfter the resurrection of Guilliman in late [[M41]], however, Dorn formulated his own protocol he began to see many of the flaws that came from overly-strict adherence to possibly circumvent the Codex Astartes known . As a result, he has reformed much of the Codex and eliminated much of its restrictions on Space Marines. New additions include the addition of [[Primaris Space Marine]] formations such as [[Intercessor]], [[Aggressor]], [[Inceptor]], and [[Reiver]] Squads, as well as the inclusion of two [[Last WallSpace Marine Lieutenant|Lieutenants]]below the Company Captain, each commanding a code phrase that would require the Imperial Fists and the Successor Chapters to bind together under one supreme commanderdemi-Company.{{Fn|12}} LikewiseFurthermore, squads in the Codex Astartes are now defined as "[[Dark AngelsBattleline Squad|battleline]] and their successors" rather than tactical, while dividing into chapters"[[Close Support Squad|close support]]" rather than assault, have remained united in their single-minded pursuit of or "[[Fire Support Squad|fire support]]" rather than devastator. These formations exist alongside the not renamed [[FallenSpace Marine Veteran|veteran]]and [[Space Marine Scout|scout]] squads.{{Fn|2615a}}{{Fn|15b}}

The Additionally, the [[Space Wolves10th Company|10th company]] Legion, however, never fully accepted the new doctrine; rather they held sacred the teachings of their Primarch, Leman Russ. For that reason, the Wolves consist of twelve a [[Great Company|Great Companieschapter]], rather than the ten mandated by the Codex, and their system of organization and promotion bears little resemblance began to that of hardline Codex chapters, such as the Ultramarines. Although the Space Wolves attempted to create Successor Chapters, the genetic instability of their include 10 "[[gene-seedVanguard Space Marine|vanguard]] made a disaster of their first attempt, the ill-fated " squads alongside [[Wolf Brothersscout squad]]s, acting as a permanent infiltration and reconnaissance force that could be attached to other companies.{{Fn|915a}}{{Fn|15b}}

In As a corollary, the immediate aftermath maximum size of the Heresy, [[Nassir Amit]], the founder and first a chapter master of the [[Flesh Tearers]]has expanded, expressed little but scorn for the Codex, finding it amusing that Guilliman, who had been absent from as can be seen in the [[Battle of Terra]], should think himself fit to impose restrictions on the other Legions.{{FnUltramarines#Companies|13}} ===Recent Reformation===After the resurrection current roster of Guilliman in late [[M41's first founding chapter]]; as can be seen there, he began to see many of the flaws that came from overly-strict adherence to the Codex Astartes. As 10th company contains a resultfull 1, he has reformed much of the Codex and eliminated much of its restrictions on Space Marines. New additions include the addition of [[Primaris Space Marine]] formations such as [[Intercessor]], [[Aggressor]], [[Inceptor]], and [[Reiver]] Squads000 marines (formerly it would contain very few, as well as the inclusion of two [[Space Marine Lieutenantneophyte|Lieutenantsnon-sergeant scout]] below s did not count against the Company Captain1, each commanding a demi000-Company. Furthermore, Squads man personnel limit in the old Codex Astartes are now defined ); this means ''even before'' company command structure marines (such as [[Battleline Squadspace marine command squad|Battlelinecommand squad]]s, [[Close Support Squadspace marine captain|Close Supportcaptain]]s, or '''and [[Fire Support Squadspace marine lieutenant|Fire Supportlieutenant]] Squads'''s), chapter command structure marines, and dedicated vehicle crews (e.g. These formations exist alongside [[Space Marine Veteran|Veterandreadnought]] Squads and [[Space Marine Scout|Scout]] Squads.{{Fn|15a}}{{Fn|15b}} Additionallys), at full strength the [[10th Company]] of a [[Chapter]] began Ultramarines have 100 marines assigned to include 10 [[Vanguard Space Marine|Vanguard]] battleline, close support, fire support, and veteran squads alongside the [[Scout Squad]]s(i.e. 1,000 total), acting ''plus'' 1 marine assigned to each scout squad as a permanent infiltration and reconnaissance force that could be attached to other companiesits sergeant.{{Fn|15a}}{{Fn|15b}}

Often, Space Marine [[Space Marine Strike Force|Strike Forces]] consist of Marines from multiple different companies attached to one central Battle Company. Members from the 6th-9th Reserve Companies can provide reinforcements and extra firepower, [[Space Marine Veteran|Veterans]] from the [[1st Company]] provide skill and wisdom to augment existing forces, and [[Scouts]] and [[Vanguard Space Marines]] from the [[10th Company]] infilitrate, sabotage, and assassinate key targets. Additionally, forces can requisition vehicles from the [[Armoury]], providing armoured support.{{CitethisFn|20a}}

Attached units will typically take the heraldry of the company they are attached to. For example, an [[Intercessor Squad]] pulled from the [[Space Marine Company|7th Company]] to bolster a [[3rd Company]] force would paint their shoulder trims red in the company colour. Similarly, a [[Bladeguard Veteran Squad]] formed of [[Space Marine Veteran|Veterans]] from the [[1st Company]] attached to a [[4th Company]] [[Space Marine Strike Force|Strike Force]] would paint their shoulder trims green, rather than white.{{CitethisFn|20e}}

Vehicles attached to While a company will generally bear the company's colour and number in a small roundel somewhere on the hullwould normally consist of ten squads, as well as attached squads can form an identifier number to distinguish between different attached vehicles of the same type.{{Fn|26c}} Transport vehicles attached to a specific squad also bear that squad's heraldryadditional ten, including squad number and battlefield role insigniataking up designations as squads 11-20.{{Fn|26c35a}}

While [[Apothecaries]] and [[Chaplains]] are usually permanently part of a company would normally consist of ten squadsCompany, while [[Librarians]] and [[Techmarines]] are considered attached squads can form an additional tento the Company but ultimately belong to the [[Librarius]] and [[Armoury]], taking up designations as squads 11-20respectively.{{Fn|35a37}}

* [[Scout Squad]] - Trainee [[Space Marine]] unit. Scout [[Land Speeder]]s and [[Space Marine Bike|Bike]] Squads are still Scout Squads.{{CitethisFn|20d}} ====Combat Squads====While the standard number of marines in a squad is 10, a squad can be split into two groups of 5 marines known as combat squads for extra strategic versatility, such as having one combat squad acting in an "assault" role with the other providing fire support.{{Fn|38}} In most cases, the second-most senior member of a squad (such as a [[Space Marine Veteran|Veteran]]) would lead one combat squad, while the [[Space Marine Sergeant|Sergeant]] would lead the other. Combat squads are usually named after their leader, similarly to full squads.{{Fn|38}}{{Fn|39}}

Members The left shoulder plate of a Space Marine's Power Armour usually shows the Marine's Chapter Badge, while the right displays squad typically bear that markings. Squad markings in a Codex-compliant Chapter consist of a squad's number laid over a battlefield role icon and squad number on their right pauldrons. [[Close Support Squad]]s utilise display a 4-way arrowto designate their battlefield role, while [[Fire Support Squad]]s display an inverted V known as a chevron, and [[Battleline Squad]]s use a simple upwards-facing arrow. [[Space Marine Command Squad|Command Squads]] bear a skull, and [[Veteran Squad (Space Marines)|Veteran Squads]] use a stylised version of the [[Crux Terminatus]] similar to a Cross Pattée. [[Space Marine Veteran|Veterans]] in [[Terminator Armour]] wear a real [[Crux Terminatus]], albeit on their left shoulder pads, displacing their Chapter Badges to their right pauldron.{{CitethisFn|20a}}{{Fn|27a}}

Some Chapters choose to display squad information on other parts of the armour, e.g. on kneepads.{{Fn|18b}}{{Fn|18c}} Squads in Battle Companies are numbered so that squads 1-6 are Battleline, squads 7-8 are Close Support, and squads 9-10 are Fire Support. However, squads 11-20 from Reserve Companies attached to a Battle Company don't appear to follow any required format, meaning they could all be Close Support squads, for example.{{Fn|20a}} The Vanguard squads in the 10th Company also don't follow the same strict numbering scheme that the battle companies do, so it's possible to have a Battleline 10th squad in a Codex-compliant 10th Company.{{Fn|41}} ====Squad Markings=Vehicles and Dreadnoughts===The left shoulder plate of a Each Codex-compliant Space Marine'Company maintains a permanent number of [[Dreadnought]]s Power Armour almost always shows and transport tanks, and can requisition more from the MarineChapter [[Armoury]].{{Fn|20a}} Vehicles attached to a company will generally bear the company's Chapter Badge. The right pad shows colour and number in a small roundel somewhere on the squad badgehull, as well as an identifier number to distinguish between different attached vehicles, this indicates although the type exact meaning of identifier numbers vary.{{Fn|Note 2}}{{Fn|26c}} Transport vehicles attached to a specific squad the marine belongs to also bear that squad's heraldry, including squad number and the number of his squad within the companybattlefield role insignia. {{Fn|26c}} Aircraft are usually organised into squadrons, which are structured similarly to Space Marine squads, except with [[Veteran SquadTechmarine]]s use piloting (usually 3) aircraft instead of infantry. Squadrons are led by a stylised version wing leader, who combines the function of the a [[Crux TerminatusSpace Marine Sergeant|Sergeant]] similar and a Techmarine. Squadrons are also often attached to a Cross PattéeCompanies, Tactical Squads use an arrowand bear that company's insignia. While there is no official marking scheme for squadrons, Assault Squads use four perpendicular arrows pointing outwards aircraft are usually marked with large blocks of colour on the wings and Devastator Squads use an inverted V known as a chevrontail for easy identification from long distances, with the wing leader's aircraft featuring the most ornate design. Space Marines Numbers applied to aircraft's hulls can also be used to differentiate between aircraft in Terminator Armour wear the [[Crux Terminatus]] on their left padsame squadron, and their Chapter Badge on their right padwith the wing leader usually being numbered 1.{{Fn|27a40}} Squad numbers are typically superimposed on the squad type insignia Battlefield roles can be given to aircraft, but many chapters choose to display them on other parts of with some having the armour, e.g. on kneepadsclose support role.{{Fn|18b40}} Aircraft can form mixed-type units, such as a Storm Wing, which contains a [[Stormraven Gunship]] escorted by two [[Stormtalon Gunship]]s.{{Fn|18c40}}

A [[Neophyte]] is the lowest rank of [[Space Marine]]. Neophytes are usually members of [[Scout Squads]], and are attached to the [[10th Company]].{{CitethisFn|20d}}

[[Brother|Battle-Brothers]] are the first rank of fully-fledged [[Space Marines]], forming the majority of a [[Chapter]]. They are divided into a wide range of squads throughout all [[Space Marine Company|Companies]] but the [[1st Company|First]]. [[Brother|Battle-Brother]] is also a term used by all [[Space Marines]] to refer to each other with.{{CitethisFn|20d}}

A [[Space Marine Veteran|Veteran]] is an elite, highly experienced Space Marine. To mark their status, Veterans wear white helmets. Veterans usually form [[Veteran Squad (Space Marines)|Veteran Squads]], but can also be members of [[Space Marine Command Squad|Command Squads]] or [[Space Marine Honour Guard Squad|Honour Guard Squads]]. Some Veterans have the ability to don [[Terminator Armour]].{{CitethisFn|20b}}

[[Ancient]]s are [[Space Marine Veteran|Veterans]] that carry a [[Space Marine Standard|Standard]]. Each [[Chapter]] has a [[Chapter Ancient]], responsible for carrying the [[Space Marine Standards#Chapter Standard|Chapter Standard]], and 10 [[Company Ancient]]s that carry [[Space Marine Standards#Company Standard|Company Standards]]. Company Ancients are usually part of the Company [[Space Marine Command Squad|Command Squad]], and Chapter Ancients part of the Chapter [[Space Marine Honour Guard Squad|Honour Guard]].{{CitethisFn|20b}}

Champions are [[Space Marine Veteran|Veterans]] that are master duellists. Each Company has a [[Company Champion]] in their [[Space Marine Command Squad|Command Squad]], while the best duellist in the [[Chapter]] is part of the [[Space Marine Honour Guard Squad|Honour Guard]].{{CitethisFn|20b}}

[[Space Marine Lieutenant|Lieutenants]] bear a red stripe bordered in white upon their helmets. A Lieutenant's right pauldron displays a skull with a red halo, similar to a [[Space Marine Command Squad|Command Squad]] icon. There are two Lieutenants per company, serving under their Captain.{{CitethisFn|20f}}

A [[Chapter Master]] is the supreme commander of a [[Chapter]]. Chapter Masters wear their own personal heraldry, combined with that of their Chapter.{{CitethisFn|20f}}

[[Chaplains]]s are [[Space Marine]]s responsible for the spiritual health of their brothers. Chaplains are just below the command level of a [[Space Marine Captain|Captain]].{{Citethis}} They belong to the [[Chaplaincy]] and wear black armour, regardless of Chapter.{{Fn|27e}} Traditionally, Chaplains are not allowed to be seen by their brothers without their signature skull masks.{{CitethisFn|20f}}

[[Judiciar]]s are trainee [[Chaplain]]s.{{CitethisFn|20f}}

[[Techmarine]]s are Space Marine engineers and mechanics,{{Fn|27h}} and can also function as pilots for some of a Chapter's larger vehicles, such as aircraft. {{Fn|40}} They wear red armour, irrespective of what chapter they belong to, and wear their Chapter Badge as normal.{{Fn|27h}}

[[Apothecaries]] are field medics, responsible for both the physical health of their brothers, but also safekeeping the Chapter's [[Gene-seed]]. Some Apothecaries, known as [[Apothecary Biologis|Apothecary Biologises]] es instead study enemy Xenos biology, discovering weaknesses.{{Citethis}} They wear white armour, irrespective of what chapter they belong to, and wear their Chapter Badge as normal.{{Fn|27g}}

*''"The Codex Astartes does not support this action."''<br>- Then [[brother]] [[Leandros]] to then -[[Space Marine Captain|Captain]] [[Demetrian Titus]], presumably that the Codex did not support leaping from a speeding [[Thunderhawk]] mid-flight via [[Jump Pack]]s to then land upon another [[Ork]] vessel also in-flight.{{Fn|30}} {{Fn|Note 1}}

*{{Endn|Note 1 - }}: [[Uriel Ventris]] was also known to have descended from a flying Thunderhawk via jump pack, though he noted it was very rarely done is incredibly difficult to land accurately on a point on the ground. He would describe this "as dangerous a combat drop as he had ever attempted."{{Fn|31}} ==Conflicting Sources==*{{Endn|Note 2}}: It is unclear whether vehicle identification numbers count all vehicles in a Company in one list, or whether different vehicle types are numbered differently.** [[Imperial Armour Volume Two - Space Marines and Forces of the Inquisition]] contains conflicting evidence, with the meaning of the number differing between vehicles and Chapters.** [[Black Crusade: Angel's Blade]], pgs. 88-89 describes the [[Blood Angels]] [[2nd Company, Blood Angels Chapter|2nd Company]] as using identification numerals to signify a vehicle's number within its vehicle squadron.** [[Insignium Astartes]], pg. ~51 states that [[Ultramarines]] [[2nd Company, Ultramarines Chapter|2nd Company]] [[Land Raiders]] are numbered individually, in a separate list from other vehicles, implying that other vehicles (e.g. [[Predators]]) might also be numbered in their own lists.** Most sources, including [[Black Crusade: Angel's Blade]], [[Blood Angels Painting Guide – Sons of Sanguinius]], and [[Insignium Astartes]], pg. ~48 agree that [[Dreadnought]]s are numbered in their own seperate list as well.

**{{Endn|20a}}: pgpgs. 16-19

**{{Endn|20x20d}}: pgs. 28-36**{{CMEEndn|20e}}: pg. 78**{{Endn|20f}}: pgs. 12-14