The warriors of the Adeptus Astartes have access to the most potent and deadly wargear the Adeptus Mechanicus can fashion for them. Potent and deadly is not the same as the most archaic or capricious. Marine wargear is invariably tried and true. It can be manufactured, maintained and supplied with a minimum of effort compared to its lethality, protective value or other additions to the continued success of the Marines. Take that iconic weapon of the Astartes: The hallowed bolt gun. It’s not the most advanced weapon ever made, but it’s incredibly reliable, versatile and deadly – the bolter is possibly the weapon responsible for the most enemy deaths since the Great Crusade.

Battle-Brothers are strongly linked to their battle armour – the sacred suits of powered armour that the Emperor designed before the start of the Great Crusade. Without the armour the Marine would still be a deadly super-human warrior, but he would be terribly exposed against the terrors of the Galaxy. The Emperor, in his infinite wisdom saw this and made sure his champions would be protected by adamantine, plasteel and ceramite. But the PA is more than just a suit of protective armour; it also enhances the marine in many ways, making him faster, stronger, smarter, and more lethal.

But a true Space Marine is not just a super-human warrior encased in advanced armour and carrying devastating weapons; a Space Marine also an integrated man/machine (the armour suit machine spirit) combat team. All designed by the Emperor himself for optimum combat efficiency, fearlessness and unflinching loyalty to mankind. Unlike the ghoulish warriors of the Dark Age of Technology, Marines were intentionally made from modified human stock – rather than designed from scratch and birthed in bio-genesis tanks. And equally important is the fact that it the human component who is in charge of the man/machine team and never the other way around; the Emperor would not see a replay of the Man/Machine wars of the Dark Age of Technology.

Space Marines have jump packs as standard war-gear. Without jump capability Marines become little more that glorified infantry; they can't even cross major rivers without help. The pack contains a micro-fusion power plant, suspensor field generator, vectored thrust unit and reaction mass (which the pack can replenish from most atmospheres). The pack allows for quick movement across the battlefield using powered jumps, or even short-distance flight (for about one minute). It is very versatile and can be employed in both vacuum (endurance is somewhat limited, but much greater than within a gravitized/atmospheric environment) and while submerged (in a sort of water-jet mode; the suspensor field acts to limit drag while the thrusters provide propulsion).

Marines may employ flight packs as needed. Flight packs have much more powerful thrusters and also contain a full contra-grav unit, allowing true powered flight and extended hover-mode. The Flight Pack can operate in the same range of environments as the jump pack (including underwater to great effect; the flight pack unit generates a more powerful field and has more thrust). The flight pack is specialist gear that is only issued to assault troops that have received training with it.

Power armour can also be deployed without the pack, resulting in a less bulky and somewhat more agile suit. Without its main power supply, however, the crystal-matrix batteries in the armour only has enough power to last 24-72 hours (depending on intensity of use) before the energy stacks are depleted. The same applies if the backpack is damaged or destroyed. With the jump/flight pack intact the suit has near-infinite endurance, as the suit siphons energy from the backpack power plant to continuously replenish the crustal-matrix stacks.

Marine power armour allows a full range of human movement, including crawling, jumping and climbing. The only thing a PA wearer can't do very well is swim; the suit weighs hundreds of pounds, too much for even the augmented strength of a suited Marine to manage (but they can 'swim' quite well using a jump or flight pack). A Marine in fully powered armour can move and lift about ten times as much as a normal soldier with little effort, more if the suit is put in enhanced power mode. Because of the added power provided by the armour Marines can move much faster than non-augmented infantry, and jumping distance is also greatly enhanced (even without resorting to their jump pack).

Marine Power armour is engineered to provide maximum deflection and damage reduction from all angles, with added focus on protection from the front quarter – Marines are by nature an offensive weapon system! Shoulder guards are enlarged to provide added protection for the neck joint/head from side/oblique attacks without having to resort to heavy fixed helmet pieces. The torso section is very heavily armoured with double thickness composite ceramite-based plating, as are the lower legs – a Marine firing from a crouched position effectively has extra cover provided by his own armour. The rear of the suit, the upper legs, the arms, and the abdomen has an average protection level. Joints are comparatively weakly protected, as they are with all armours – care has been taken to minimize exposure and maximise the chances of deflection.

Marines are highly reluctant to go into prone position, as this compromises the protection offered by the shoulder guards, exposing the relatively fragile jump pack unit. It also greatly reduces mobility, which is anathema to Marine combat doctrine – to stop moving is to lose the initiative, and loss of initiative invariably leads to defeat and dishonour. The only time Marines regularly go into prone position is for infiltration missions that absolutely require this; in that case the jump pack may be abandoned or the Marine may opt to wear lighter armour. Such missions will usually be handed to Marine Scouts if they are available.

The defensive layout of the armour ties in with Marine doctrine; it calls for rapid oblique advances on the enemy, maximizing the protective profile of the suit while also making it difficult for enemy gunners to track the movement of the Space Marines. When advancing in the open Marines will leap-frog, using the increased mobility afforded by their suits (including powered jumps) to quickly move from cover to cover. If no cover is available they have the option of going into kneeling position, where their armoured legs/shoulder/chest plates offer excellent cover in itself.  Head-on charges are not (contrary to Imperial propaganda) Chapter-approved, except in close quarters fighting where engagement time is very short. Such charges should always be preceded by the use of grenades to obscure visibility and supporting fire to force enemy gunners to take cover, allowing the Marines to enter close-combat without exposing themselves to masses of lethal point-blank defensive fire.

A Marine will never rely solely on the protection of his armour, but constantly seek to use movement and terrain to augment his defences. The suit itself offers almost complete protection against small-arms fire, concussion damage and shrapnel. The suit can, however, be breached by high-velocity armour-piercing rounds or hi-power lasguns it they strike joints or other lightly-armoured portions of the suit. Bolt guns can deal effectively with power armour if clean hits can be achieved; only the heavy ceramite plates on lower legs/shoulders/chest can resist direct hits from such weapons with any degree of certainty.  Moreover the explosive damage caused by internally-exploding bolts can incapacitate or kill even a Space Marine, making the bolter a premium Marine-stopping weapon system (but then again the bolter can kill just about anything).

Power armour is not just heavy slabs of plasteel ceramite; it’s a highly advanced sandwich of materials that provides the maximum protection to weight ratio available to Imperial science. PA protects not only from projectiles and concussion effects, but also functions against the full range of direct energy weapons seen on the 41^st Millennium battlefield. It must be noted, however, that no armour system provides complete protection against hi-energy weapons like lascannon, plasmatic ordnance or fusion systems. Marines that expect to be exposed to any quantity of such weapons are best protected by a combination of Tactical Dreadnaught Armour and personal refractor fields.

Power armour is completely sealed and offers full protection from a number of environmental hazards, including radiation, high pressure and vacuum. The suit can replenish its stores of oxygen and other compounds by processing the local atmosphere. In less hazardous environments the suit has an efficient filtration system that gives near-infinite endurance given proper field-maintenance rites. The suit comes with a partial auto-med suite that includes an auto-injector system with a full range of combat drugs, a body-fluid/waste filtration system, and other medicae-related subsystemss. The suit also includes and emergency nutrition that can keep a Marine operational of two weeks even if no other food supply is available.

Propaganda usually portrays Marine heroes in full parade colours charging into the fray. This is not Chapter-approved tactics except under highly special circumstances (such as final resort defiance suicide charges). This image of the Marine has been carefully crafted by the High Lords to give the marines yet another advantage over their heretical enemies. Rare are those with the imagination required to understand that the Marine can and will use stealth as needed to defeat their enemies. Indeed they are all well versed in the art of infiltration – no Marine is ever made a Battle-Brother until he’s proven himself as a Marine Scout many times over. Integrated stealth systems ensure that the Marine is not prematurely detected; stealth systems include full spectrum cameleoline camouflage, radiated-energy dump (stored in the suit's crystal-matrix capacitors), and ray dispersal technologies. Although still detectable by a skilled auspex operator at shorter ranges, a stationary Marine is nearly undetectable without specialized equipment except at point-blank ranges. While moving, firing or otherwise engaged in operations Marines are easier to detect.

Power armour also includes a wide range of sensors, giving the Marines unprecedented access to battlefield intelligence. The suit offers visual and audio pickups that can peer into bands even beyond those accessible to the super-human sense of the Marines. There are even olfactory pickups included. The full range of electromagnetic sensors is also included, active auspex suites, sensor illumination warning systems, powerful vox- and cogitator links etc. The suit comes equipped with a triply redundant multi-band encrypted communication suite; it takes a lot of jamming to isolate a Marine from his unit and breaking the encryption protocols have proven rear-impossible. A Marine linked into his unit communications grid enjoys an unprecedented advantage in terms of command, control, communications, intelligence, surveillance, and target acquisition (C3IST).

Each suit of Astartes Power armour links directly into the Marine central nervous system through a series of neural jacks installed in the Black Carapace. This ensures optimum performance from the suit/Marine team; the suit and the soldier are, quite literally, as one. Marine Power armour hosts a powerful integral machine spirit that oversees the suits numerous subsystems and logic routines, and controls the data-flow between machine and man. The machine spirit is also tasked with keeping the Marine in touch with his Battle-Brothers as well as any other battlefield presences; utilizing powerful encrypted vox-links. The combination of nerve-link interface and machine spirit controller makes any form of HUD (or similar archaic tech) superfluous; everything is fed directly into the Marine's brain through the nerve-link. A complete virtual reality simulation, based upon input from the Marine's own suit as well as any other battlefield data relayed from other source, can be projected directly into the mind of the wearer.

Marine Power armour also features a host of less advanced subsystems, including; retractable boot and gauntlet spikes (primarily for traction and climbing, but usable as melee weapons), mag-lock boots for traversing spaceship hulls, voice-amplifiers, external directional lighting, etc. The suit also comes with a full array of STC utility attachment points to allow the Marine to easily add any type of mission-specific equipment to his loadout.