Space Marines - Space Marine Combat Doctrine: Every Space Marine Chapter is fiercely proud of its history and achievements and each is marked out by its own distinctive colours and Chapter heraldry.These colours and iconography were established at the time of each Chapter's Founding and are displayed with unadulterated pride upon all armour and vehicles owned by the Chapter.The wargear of the Chapter is maintained with painstaking precision and many items have been covered over the millennia in fine lines of intricate devotional script in High Gothic, with each line detailing a battle honour of the Chapter won by a previous user of the weapon.Each Chapter is commanded by an officer usually known as a Chapter Master, who holds a rank equivalent within the Imperial hierarchy to that of a planetary governor.Each Chapter is a small, mobile army and although each contains only 1,000 battle-brothers, a Chapter's actual combat potential is equivalent to at least ten times that number of normal troops drawn from the Astra Militarum (Imperial Guard).Each Chapter has its own transports, support staff, armourers and Chapter fleets of warships and are intended to respond to any type of threat that can emerge anywhere in the galaxy.Because they are so mobile compared to other Imperial military units, the Space Marines are often the first servants of the Emperor to arrive at a scene of conflict and they are used to mount deep strikes, raids and devastating surprise attacks.The archetypal mission for which the Space Marines were created over 10,000 Terran years ago is the planetstrike, or planetary assault. Such an offensive begins with the Astartes' Chapter fleet engaging with and clearing away any defending starships and neutralising the target world's orbital defences, ground-based laser batteries and missile silos.Enemy ground defences are sabotaged by the Chapter's Scout Marine or Vanguard Marine forces or captured by full Astartes from its Battle Companies.Often the bulk of a Space Marine force deployed to a planetary assault will deploy directly into battle, forcing a decisive engagement to take advantage of the considerable shock of their appearance upon the field.When the Space Marines arrive in this manner they must deploy as rapidly as possible to maintain the element of surprise that plays such a crucial role for them in achieving battlefield success.To this end, Space Marine warships are equipped with hundreds of Drop Pods and large hangar bays filled with deadly Thunderhawk gunships. The contrails of these craft high in a world's atmosphere are often the only harbinger of a Space Marine assault.As the Chapter's Drop Pods and Thunderhawks streak through the embattled sky towards their rendezvous with blood and fire, the enemies of the Emperor come to realise that their doom is at hand.The Space Marines always prefer to deploy right into the heart of the enemy's force and proceed to unleash a devastating barrage of bolter fire. The initial shock of this assault can often break an enemy force before a campaign has barely begun, ending a rebellion or forcing an alien invader off-world in one fell stroke.These shock assaults are usually spearheaded by squads of Terminators drawn from a Chapter's Veteran 1st Company who teleport directly into the heart of the foes' lines and are supported by heavier units like armoured vehicles that have been delivered to the world's surface by Thunderhawk Transporters.Each company of a Chapter is able to field a mix of battleline, close support, fire support and Veteran squads depending on its type.An entire company of Astartes is rarely fielded as a tactical force. Instead, each Space Marine force is exactly tailored to the tactical requirements of the combat mission at hand, usually with elements drawn from the versatile Battle Companies.Such a force might consist of only 3 or 4 squads supported by individual squads drawn from other companies, as well as a complement of armoured vehicles and Dreadnoughts. This force will be led into combat by a Captain, a Lieutenant, a senior Veteran Sergeant, a Chaplain or a Librarian who serves as the Force Commander.On very rare occasions, a Space Marine Chapter will be called upon to carry out a mission or face an enemy of such size and power that it must deploy a large portion of its total strength.In these instances, forces consisting of 200 or even 300 Astartes and their supporting vehicles are not uncommon. Such a force is deployed only to those locations where the enemy's advance must be stopped at all costs.For instance, during the Second and Third Wars for Armageddon it was determined by the High Lords of Terra that the Ork Warlord Ghazghkull Thraka had to be prevented from extending his WAAAGH! beyond that strategically located Hive World lest his Greenskin hordes gain footholds on more populous worlds in the Segmentum Solar and wreak absolute havok on the Imperium's heart.As such, several legendary Astartes Chapters like the Blood Angels, Salamanders and Black Templars deployed several full Battle Companies in their supreme effort to halt the advance of the Orks. Such was their skill that Armageddon became a new word for total war in the Ork "kultur."The nature of the Adeptus Astartes' missions means that a Chapter's various components may be spread across the galaxy at any one time, with individual detachments involved in separate conflicts thousands of light years apart.It is very unusual for all 10 companies of a Chapter to be gathered in the same place at the same time and centuries can pass between gatherings of an entire Chapter for a single mission.As a result, the deployment of an entire Space Marine Chapter indicates the need to combat a threat that may rend the very fabric of the Imperium itself if left undefeated. The deployment of such a force can only be requested by the High Lords of Terra and is led by the Chapter Master in person. Such a gathering of martial power can bring a Fortress World to its knees, halt an alien invasion or even hurl back a Black Crusade.Legendary, existential threats to the Emperor's realm such as the Helican Schism, the Macharian Heresy and the Tyrannic Wars have seen the need to call up entire Chapters. Whole worlds have become shrines to remember the fallen of these conflicts.Each of these campaigns engulfed large regions of Imperial space and involved countless millions of troops, yet were ultimately decided only by the unmatched heroism of a relatively small number of the Emperor's Angels of Death, the Space Marines.