The Space Marines are the product of genetic engineering, intensive training, biochemical alteration and implant surgery which takes them to the limits of Human development and beyond. A Space Marine can survive terrible wounds, and heal with superhuman speed, and perform incredible feats of strength and endurance. A Marine is genetically related to all the other members of his chapter, since each Marine carries some genetic material from the Chapter's founder, or Primarch- one of a small group of super-humans created by the Emperor and his scientists.
In numerical terms, the Space marines are a small force compared to the countless billions of Imperial citizens, but their superhuman ability and fearsome reputation makes them worth many times their number in conventional troops. They are held in awe throughout the Imperium.
Each Space Marine Chapter is a fully self-sufficient fighting force, with its own space fleet and machine pools as well as support and technical personnel. The Techmarines are trained by the Adeptus Mechanicus, and can repair and maintain almost any piece of military equipment, from a bolter to a spaceship.
A Chapter's fleet is its home, providing accomodation, training facilities, machine shops, armouries, shuttlesilos, chapels, a mousoleum and every other facility the Chapter requires. The fleet travels endlessly through the galaxy; task forces split off from it for individual missions or campaigns, and rejoin the fleet when their mission is accomplished.
The Chapter provides for all a Marines's needs. Tradition and ritual are of great importance, with as much emphasis on moral welfare as on physical training and combat skills. The Chapter is a Marine's family; all other ties of blood and loyalty are renounced. A Space Marine is devoted to the Emperor, to his chapter, and to the craft of war; these things are his entire life.
Each chapter is headed by an Imperial Commander - during the Horus Heresy, most of the Commanders were Primarchs. In addition to their support and technical personnel, a Chapter contains tens of thousands of Marines. (Note that after the Heresy new Chapters were formed with far smaller complements so that no Commanders would ever wield the same power as Horus).
Space marines may be recognised by their distinctive powered armour, which includes air and blood purifiers, drug injectors and communications equipment. Neuro-plastic fiber-bundels replicate and amplify the wearer's movements, so that powered armour is no more combersome to wear than a normal suit of cloths.
Each Chapter has its own colours and insignia, which are used on its armour and vehicles as well as on flags and banners which are often carried into battle. It also has its own particular rituals and traditions. The Space Wolves for instance, have a completely different Litany of Combat to the Ultramarines. Even the most basic activities, such as weapon checks and maintinance routines are turned into rituals; a Marine's every action must express his devotion to his Chapter.
In the earliest stages of the Horus Heresy, the Space Marines who sided with the Warmaster kept to the original colours and rituals of their chapters. Later on, however - particularly after the death of Horus and the withdrawal from the Sol system - this began to change.
The litanies proclaiming devotion to the Emperor had already been dropped, and they became replaced with declarations of allegiance to Horus. As the feral-world cults introduced by Horus spread throughout the \traitor Chapters, most Chapter rituals changed beyond recognition. Insignia and colours also began to change; most common was the replacement of Imperial insignia with the Eye of Horus or with symbols from the feral cults. Some Traitor Marines went as far as to re-paint their armour in new colours.
Space Marines have access to the full range of Imperial weaponry and equipment. Their training and biochemical engineering ensure that they are natural masters with any type of weapon, from the rocks and sticks of feral-world savages to the sophisticated needlers and neuro-disruptors favoured by spies and assassins. For nearly all their combat duties, however, they use the standard weapon mixes, relying on a narrow range of favoured general-purpose weapons.
The standard Space Marine weapon is the boltgun, or bolter. This is a light rapid-fire weapon, firing a hail of small-calibre explosive shells. Bolter shells generally use mass-reactive fuses, so that they explode after penetrating the target, rather than upon impact; this makes the bolter a highly effective anti-personnel weapon.
The main close assault weapon is the bolt pistol, a smaller version of the Bolter which works on identical principles. While it lacks the range of the Bolt gun, its hardier pistol configuration makes it ideally suited to close fighting.
Other favoured close assault weapons include the power glove and chainsword, both of which are most commonly issued to officers leading assault troops. The power glove is a scaled-up metal gauntlet surrounded by an energy field which gives it the strength to puch through armour and even steel bulkheads. The chainsword is as it sounds - a sword-like weapon whose edges are fitted with a loop of moving blades.
The Space Marines also use a wide range of support weapons, of which the most common are heavy bolters, melta-guns, plasma guns, las-cannon and missle launchers.
The heavy bolter is a larger version of the bolt gun, which can lay down a curtain of fire across a wide area. While its firepower against personnel targets is devastating, its shells are too light to harm armoured vehicles.
Also known as the melter or fusion gun, the melta-gun is a heat weapon, whose short range is balanced by its effectiveness against both infantry and vehicles. A small-scale controlled fusion reaction inside the weapon's firing chamber causes it to project a blast of heat so intense that metal and even stone can be melted almost instantly.
The plasma gun fires small packets of superheated gas plasma. Like the melta-gun, its killing power helps make up for its short range, and it is equally effective against infantry and armoured vehicles.
The las-cannon, or laser cannon, is a favourite anti-vehicle weapon, with its long range and sufficient puch to knock out a Land Raider. As well as being popular infantry weapon, it is often mounted on vehicles.
The issle launcher rivals the las-cannon as the most popular infanrty weapon. Its variety of loads makes it equally effective against vehicles and infantry, and its range is equal to that of a las-cannon.