The '''1st Company''' is the most powerful company, consisting entirely of [[Space Marine Veterans|Veteran Space Marines]]. In addition to having access to the Chapter's rarest and most advanced technology, the 1st Company is the only one trained in and equipped with [[Terminator Armour]]. In addition to Terminator Squads, the Veteran Company also fields [[Bladeguard Veteran]]s, the [[Space Marine Honour Guard]], [[Sternguard Veteran]]s, [[Vanguard Veteran]]s, and veteran [[Intercessor]]s{{Fn|2}}. Transport for the 1st Company includes [[Land Raider]]s, [[Repulsor]]{{Fn|2}}, [[Stormraven]]s, and [[Rhino]]s. It may may also include [[Dreadnought]]s, as these fallen heroes are encouraged to remain with their battle-brothers.{{Fn|5}} The 1st Company rarely fights as a single unit, but instead its members are attached on an as-needed basis to other companies, lending their superior experience, skill, and equipment on campaign.{{Cite This}}

The 2nd, 3rd, 4th and 5th Companies are known as '''Battle Companies''', as they generally form the main battle force deployed for engagements. All four Companies have the same organisation, split into 6 '''[[Battleline Squad]]s''' which consist of [[Tactical Squad|Tactical], [[Intercessor Squad|Intercessor] and ], [[Intercessor Infiltrator Squad|Infiltrator]], and [[Heavy Intercessor]] {{Fn|2}} formations, 2 '''[[Close Combat Squad]]s''' which consist of [[Assault Squad|Assault]], [[Assault Intercessor]]{{Fn|2}}, [[Assault Centurion]], [[Reiver Squad|Reiver]], and [[Inceptor Squad|Inceptor]] formations, and 2 '''[[Fire Support Squad]]s''' which consist of [[Devastator Squad|Devastator]], [[Hellblaster Squad|Hellblaster]], [[Eradicator]]{{Fn|20}}, [[Eliminator Squad|Eliminator]], [[Centurion Devastator]], [[Suppressor Squad|Suppressor]], or [[Aggressor Squad|Aggressor]] formations. Each Battle Company also includes around two [[Dreadnought]]s, and maintains their own motor pool of [[Rhino]], [[Invader ATV]]{{Fn|2}}, [[Storm Speeder]]{{Fn|2}}, [[Impulsor]]s, and [[Razorback]] transports, [[Land Speeder]]s, and [[Space Marine Bike]]s.{{Fn|5}}