Created first on earth in the thirtieth millennium and intended to spearhead the forces of humanity in the great reconquest of the galaxy known as the Firs,t Crusade, the Space Marines have become the Imperium's finest warriors and its most identifiable defenders.

Pictured here is a standard trooper. Though he would be considered a mighty warrior for any other army, among the Space Marines he is merely one of a thousand Battle-Brothers that make up a Space Marine Chapter. Each Marine represents the culmination of thousands of man-hours of training, development and equipment. Recruited from the most promising youths of martial societies all around the Imperium, a Marine is biologically engineered to make him stronger, faster and tougher than any normal human ever could be, able to endure the harshest conditions without concern.

Part of this engineering takes the form of the implantation of new organs, and the Codex Astartes lists no less than nineteen different organs that are implanted as part of a Space Marine's development. These include such obvious enhancements as a secondary heart and a multi-lung as well as obscure, but no less important, additions such as the Ossmodula which strengthens and enlarges a marine's skeletal structure (even to the extent of fusing solid the ribcage). These implants are cultured from genetic material known as gene-seed, the genetic inheritance of a Chapter that is shared by each one of its marines, both past and present. In this way, every marine has an inextricable link to his Battle-Brothers and the Chapter's history.

Each Chapter has its own methods of recruiting young warriors to fill its ranks. Many are based on a single home world and recruit solely from that populace, setting trials and tests for prospective candidates to weed out all but the strongest and the most faithful. These worlds are often technologically backward with strong militaristic societies, where male children who show potential are pushed harder and harder in order that they may one day have a chance to join the ranks of the star warriors.

It is always a great honour for a family to have a son chosen by the Space Marines, even for societies with little conception of the greater galaxy beyond their world. The Space wolves are an example of this. The Wolf Priests of the Space Wolves scour the warring, Dark Age tribes of their home world of Fenris for their strongest and bravest youths, while Ultramarines traditionally draw their candidates from the elite training barracks of a whole group of planetary systems known collectively as Ultramar, the realm of the Ultramarines.

Other Chapters have no one single home world and travel the galaxy in gigantic fleets of battleships, recruiting either from a regular series of worlds or from the war zones to which they are assigned. The Black Templars are one such example of a fleet-based chapter.

Once recruited, these youths become neophytes and begin their regimen of training and biological enhancement. Successful completion of this course is by no means assured, nor even is survival. Astartes training pulls no punches, and the surgical procedures have degenerated into arcane rituals. Those few who ultimately go on to prove themselves worthy will become initiates of the Chapter and become available for limited active duty, most often as a member of a scouting company, but this varies from Chapter to Chapter.

The boltgun or bolter is the codex issue armament for Space Marines. It is a short, compact weapon that fires a missile or bolt substantially larger than a bullet. The bolt contains an armour piercing tip, an explosive and a mass reactive detonator, causing the bolt to detonate after it has pierced armour, blowing the target apart from the inside. Its destructive power and limited effective range suits the Space Marines' typical shock or close support role on the battlefield.

Boltguns are made in limited quantities and to the highest standards using the most costly materials. Even bolts are expensive to make and cannot be easily fabricated outside of specialised workshops.

Boltguns require constant attention and regular expert maintenance if they are to work properly. Each marine is scrupulous in his attention to his weapons as not only do they allow him to carry out his duty on the battlefield but they are also a symbol of his position as a chosen of the Emperor. Marines do not so much as service their arms as they do venerate them. Master-crafted bolters are treasured artefacts and some have been maintained by Space Marine Chapters for hundreds or thousands of years.

The boltgun's smaller cousin, the bolt pistol, functions in a similar manner and is used as a sidearm by officers and assault squads where the reduced range is more than compensated for by its manoeuvrability in close-quartet combat.

Conversely, the heavy bolter and the storm bolter are heavier versions of the same principle. The heavy bolter is used as an anti-infantry support weapon by Tactical and Devastator squads, while the Storm Bolter is the standard sidearm of Terminator squads.

This enclosing suit of armour is worn almost exclusively by the Space Marines. It is made from thick ceramite plates and would be heavy and cumbersome but for electrically motivated fibre bundles implanted in the armour that replicate the movements of the wearer and supplement his considerable strength still further. The last implant of each marine is known as the Black Carapace which is a layer inserted beneath the skin itself fitted with neural sensors and transfusion points. These artificial plug-in points mesh with features integral to the powered armour allowing it to function; without the carapace the armour would be worse than useless. Power armour is therefore the most distinctive feature of a marine and is therefore the true mark of the Adeptus Astartes.

There are other older types of power armour in service which are very different in their design. Some Space Marine Chapters use only a single type of armour while others (especially those who have existed since the dawn of the Imperium) have a large store of previous designs and make use of them.

Many of the older variants have special associations for particular Chapters and may be worn by ceremonial guards or by elite units. Other Space Marine Chapters are less formal in their use of armour, mixing various types into their fighting units with little or no regard for conformity. The degree of uniformity within a Space Marine Chapter varies a great deal and is often determined by historical precedent or tradition, but even where the same armour is issued, the heavy degree of personalisation and ornamentation instinctive to all marines means that no two sets will be identical.

Developed from sealed environment suits used inside the high-pressure castings of plasma reactor shields and the holds of bulk chemical carriers, Terminator armour was designed to give the maximum protection possible in the most lethal of combat environments. The armour is massively bulky and contains a full exo-skeleton arrangement of fibre bundles and adamantium rods to support the heavy gauge plasteel and ceramite plates that form the outer carapace. They are extremely valuable and often very old, kept in a highly secure Chapter armoury and maintained and repaired religiously. Only the most experienced veterans of the Chapter (often the First Company) will ever have the chance to wear it and only then in situations where its deployment is justified, typically in deadly short-range firefights in cramped hive cities, the breach of a siege or against lethal aliens in labyrinthine space hulks.