Changes

==Early History==

Chapters were originally an organisational unit used by the [[Thunder Warriors]]. During the [[Great Crusade]], the Space Marines were organised into [[Space Marine Legion|Legions]], further divided into [[Space Marine Company|Companies]]. Chapters were adopted by some of the Legions as an intermediate level of organisation.{{Fn|2b}} The [[Ultramarines]] Legion, led by [[Roboute Guilliman]], became the largest of all the Legions, thanks to Guilliman's tactical mastery and a steady flow of new recruits from [[Ultramar]].{{Fn|1a}} At the time of the [[Horus Heresy]], the Ultramarines Legion was divided into twenty-five Chapters, each composed of ten Companies, each company composed of roughly one thousand Marines.{{Fn|2b}}

==Organisation==

A so-called [[Codex Chapter]], meaning a Chapter which closely follows the doctrines of the [[Codex Astartes]], is made up of ten [[Space Marine Company|companies]], each consisting of one hundred Marines and commanded by an officer with the rank of [[Space Marine Captain|Captain]]. Below the Captain are two [[Lieutenant (Space Marine)|Lieutenant]]s which each command a Demi-Company.{{Fn|5}} Generally, the [[First Company]] is made up of the Chapter's most experienced [[Space Marine Veteran|Veteran]]s, while the Second through Ninth consist of more ordinary warriors. Some individual companies are specialised assault or support companies, possessing larger proportions of [[Assault Squad|Assault]], [[Devastator Squad|Devastator]], [[Hellblaster]], [[Eradicator Squad|Eradicator]]{{Fn|8}}, [[Aggressor]], [[Reiver]], and [[Inceptor]] squads. The tenth company is a [[Space Marine Scout|Scout]] force, made up of [[neophyte]] Space Marines not yet proven in battle. Typically, a standing force of 100 [[Vanguard Space Marine]]s are attached to the 10th Company.{{Fn|6}} The Chapter is further bolstered and supported by a [[Librarium]], [[Armoury]], [[Apothecarion]], [[Chaplaincy]], and [[Space Marine Fleet|Fleet]].{{Cite This}}

===Fleet===

All Space Marine Chapters maintain a fleet of some sort. By the edicts of the [[Codex Astartes]], the ships of the Space Marine Chapters are to be focused on planetary assaults instead of naval combat, although some Chapters circumvent or outright ignore this rule.{{Fn|14}}