The battle barge is the largest and most powerful Space Marine vessel. It is a brutal craft, extremely heavily armoured and shielded, and outfitted with enough firepower to crack open a world.

Planetary Assault

After the Horus Heresy, measures were taken to contain the power of the Space Marine Legions, solemn decrees that would ensure no single individual could ever again command such might in isolation. As is well documented, the Legions, each numbering thousands of Space Marines, were divided down into smaller warhosts called Chapters; each of only a thousand warriors. What is perhaps of greater importance is that the Space Marines were divorced from the old Imperial military: the new Adeptus Astartes Chapters would no longer hold dominion over vast fleets of battleships or grand regiments of vassal soldiery. If they were to triumph among the stars and stand resolute against the darkness of the void, they would need to work within the Imperium, and as part of it. Since that time, Space Marines have been granted only such warships as are needed to patrol their system borders, and deliver them to battle. To this day, the primary function of their fleets has been to transport battle-ready forces of Space Marines into war.

Though formidably armed and armoured, the battle barges of the Space Marines are no exception to this rule, and were designed first and foremost to facilitate full-scale planetary assaults. Each has enough hold space to accommodate three full companies of Space Marines, along with their vehicles and support elements. Indeed, the majority of a battle barge’s interior hull-space is given over to launch bays, muster decks and transport holds. Housed there are squadrons of Thunderhawk gunships, an array of intra-system craft, and dozens of drop pods. With such resources at its command, a battle barge can deploy almost all of its forces simultaneously, putting its entire complement of Space Marines on the front lines within minutes of reaching orbit. The speed and ease with which this is accomplished has caught many a foe off guard, allowing them little time to prepare before the angels of death bring fire and vengeance to their door.

Considering its size, a battle barge has little in the way of Space Marine crew. The warriors of the Adeptus Astartes are too rare and too valuable to be tasked with performing the myriad mechanical functions required to keep a warship at operational readiness. Instead, they act as officers, overseeing the ranks of servitors and Chapter serfs who carry out other, less critical duties; performing all of the menial and manual tasks unworthy of their Space Marine lords. Yet even these subordinates are too precious to be wasted in the gunnery decks. Loading and calibrating a starship’s weapons for firing is a perilous undertaking. Plasma wash, unscheduled detonations and residual radiation keep the attrition rates in these areas high. Those with enough luck and the fortitude to survive such daily toil are soon claimed by combat, beaten past their physical tolerance by a gang-master’s whip or obliterated by enemy fire targeted to rob a battle barge of its capacity to attack. With such high mortality rates, the crewing of the gun decks falls to an indentured underclass of slaves and vat-grown dregs. In this way, their worthless lives are given purpose, for even the lowliest may redeem themselves by giving their lives in service to the Emperor and the Imperium.

Like the smaller strike cruisers, although they are each cast from the same STC templates, battle barges are not finished to a singular design. Their outer hulls and internal layout vary from Chapter to Chapter and even from one to another within a given Chapter. TheRaven’s Claw, the oldest of the Raven Guard’s surviving battle barges, has none of the sensor towers or ostentatious sanctums that protrude from the spines of most battle barges, and its profile is kept as small as possible. By contrast, the Ultramarines battle barge Macragge’s Honour is studded with towering edifices to the Emperor’s glory, and the prow of the Executioners’ battle barge Death’s Shroud is fashioned into a grim-set skull.

The Victus, an ancient battle barge and the flagship of the Flesh Tearers, has sailed the void since the days of the Great Crusade. Long-forgotten records, held in stasis and sealed to all but the most senior among the Imperium’s agents, note that the Victus was long ago refitted by the Tech-Priests of Mars at Chapter Master Amit’s personal request. The extent of the refit – and what debt the Flesh Tearers might still owe Mars for its undertaking – is unknown. However the ship has remained the subject of legend and speculation, and coupled with the dubious rumours surrounding the Chapter itself, the secrets contained within the Victus’ corridors have become a matter of interest to several members of the Inquisitorial ordos. Few have dared to question it in open forum, lest Master Seth seek ‘compensation’ for such a slight. Inquisitor Corvin Herrold was reported to have boarded the vessel looking for answers. His report as yet remains un-filed.

Armour and Shields

The magos-architects and master artificers who built the first battle barges knew full well the terrible storm of violence such a vessel would have to suffer. In order to deliver its payload of Space Marines and attack craft, a battle barge needs to enter a planet’s orbit, leaving itself open to attack from nearby ships and ground-based orbital defences. Depending on atmospheric and gravitational conditions, successful deployment may require the battle barge to enter a synchronous or low orbital hold, making it even more vulnerable to attack. To compound the problem, the sheer size of the vessel makes it easy to target, and its low engine power-to-mass ratio makes it unable to execute dynamic evades. With deployment complete, a battle barge is then expected to remain defiant in orbit, an immovable object acting as guardian over the Space Marine units below. In short, a battle barge will absorb more fire and weather more damage in a single mission than most warships are capable of withstanding over the course of their service. Fortunately, a battle barge is almost indestructible.

Constructed with its unique role in mind, the battle barges’ skeletons were forged from a an ultra-dense alloy. The rare base mineral can only be mined from the sites of recent volcanic eruptions, and is further hardened by ballast compression tanks situated on high-gravity moons. The pressurised environment hardens the alloy, ensuring the superstructure is as solid as the doors protecting the Emperor’s throne room itself. These inner frameworks were then girded in kilometres of hardened plasteel and adamantium, and edged with thick ferrocrete buttresses that surround the main hull like a reinforced rib-cage. Finally, a second and ablative layer of armour was added to each vessel’s prow, forging an impenetrable figurehead for the indomitable fury of a battle barge.

Like all Warp-capable vessels, battle barges are protected by Geller fields, arcane devices that create a bubble of realspace around a ship as it passes through the tides of the Immaterium. Unlike Imperial Navy warships that are required to spend large portions of their deployment guarding a single system, and who are called upon to travel in the warp infrequently, battle barges are in constant motion, traveling from one war zone to the next without respite. Such frequent Warp travel puts these prized vessels at great risk, and as such they are frequently outfitted with two inter-connecting Geller fields. Should one fail, the other will continue to protect the battle barge from the Warp’s hostile environment and the foul entities that dwell there. Yet this extra precaution has not always proven enough. The denizens of that twisted realm are relentless and on at least one occasion have conspired to breach both fields simultaneously.

The Novamarines battle barge Liberator, for example, was found drifting near its last recorded entry point. A stricken hulk, the initial salvage crew found no signs of life aboard. A Grey Knights kill-team was dispatched to cleanse the ship, plunging into the madness that had enveloped it. Reports of the incident are sealed, but even though their helm-logs reported a mission time of seven hours, it was more than a hundred days before they emerged from the craft.

In realspace, battle barges are protected by a group of layered void shields, wavering bands of energy that spark around the vessel to create a teardrop of invisible force. These energy barriers are capable of absorbing or deflecting the worst excesses of stellar radiation and meteor showers, and can sustain a succession of weapon hits and explosive impacts before overloading. Once overloaded, the shield generators must be power-cycled in order to let them vent off the excess energy. This is not a simple process – many slaves and Chapter serfs lose their lives in the resulting plasma fires and sparking energy discharge.

The shields protecting a battle barge are, however, among the most sophisticated that the Emperor’s armies have at their disposal. Segmented into a series of zones, it is possible for an area of shield to fail without leaving the ship entirely exposed. Further to this, energy can be siphoned from one zone to another, and redirected to where there is the most need of protection. In dire circumstances the shields’ energy can be driven up past their normal maximum. This temporarily provides the battle barge with greater protection but soon burns out the generators, and renders the shields inert. Long is the list of bold Space Marine captains who, when faced with overwhelming odds, have used this tactic to close to attack distance, and claim victory from certain defeat.

Though often severely damaged, some beyond repair, there are scant recorded reports of battle barges being destroyed outright. Perhaps this is just as well, for each Space Marine Chapter typically has only two or three of three of them under its command. They are as much prized relics as warships, icons of strength and endurance that echo the might of the Space Marines, and the resources required to build them anew are difficult to come by. The loss of even a single one of these vessels would not only be a great blow to the military capabilities of a Chapter, but would also damage its morale, robbing it of part of its proud warrior history.

Bringers of Destruction

The primary weapons of any battle barge are their dorsal-mounted bombardment cannons. Each cannon comprises a series of heavyweight batteries, huge turret-mounted linear accelerators that launch salvos of heavy magma bomb warheads. As the name suggests, bombardment cannons were primarily developed to bombard planets from high orbit, a task at which they excel. A battle barge will begin firing as soon as it reaches orbit and will continue to rain destruction down on a planet even as its complement of Space Marines is hurled downwards in their assault craft, clearing a path for their deployment on the ground. Capable of obliterating almost any manner of planetary defences, bombardment cannons will first be directed against missile silos and laser towers, ensuring that the Space Marine attack force can proceed unmolested, before being used to take out command bunkers and shield generators, aiding their swift domination of the planet. On more than one occasion, a single salvo fired into a dense population centre has ended the conflict before it has gathered any real momentum, shocking a world’s leaders into seeing the error of their ways and quickly swearing fealty to the Emperor once more.

Thanks to their gene-modified constitution and advanced armour, Space Marines can wade through a blast zone untroubled by the radiation and toxic residue left behind by a bombardment cannon strike. When operating as a self-contained force, this allows them to receive close fire support from an orbiting battle barge. Using tight-focus marker beacons they are able to direct surgical bombardments to clear their advance or protect their flanks and rear from counterattack. When working as part of a combined Imperial Guard action, such measures are usually avoided – however, Captain Barras Varlock of the Iron Hands Chapter infamously ordered a close proximity strike at the battle of Yoyung Prime. He sought to expedite victory, allowing his forces to continue on to Secundus, and gave no thought to the disastrous consequences for the Gadan Ninth Regiment that fought in support of his warriors. In the aftermath of the conflict, the surviving Imperial Guardsmen quickly succumbed to radiation sickness and died within a matter of weeks.

In extreme circumstances, or when the enemy force is so well entrenched on a world that even a sustained assault will not break their hold on it, bombardment cannons can be used to sunder entire continents, smashing them from the face of a planet in a cacophony of violent explosions. Indeed, a concentrated, prolonged bombardment can crack tectonic plates, sending massive earthquakes and tsunamis of destruction rippling out across a globe.

Battle barges are one of only a few Imperial warships capable of carrying Exterminatus-class weapons. So terrible are these devices, so irrevocable are their consequences, that their use must be sanctioned at the highest levels. Even a Chapter Master must be prepared to answer for his actions should he authorise the use of such extreme force.

When a world is deemed beyond saving, when its populace has fallen too far from the Imperial fold, a battle barge will descend into low orbit and begin the task of Exterminatus. Spreads of virus bombs turn the planet’s landmass and organic matter into corrupted slurry which can be burned away by firestorm or lance beams. Yet sometimes, such a solution is not enough. Should a planet’s skies echo to the resounding laughter of Daemons, should it fall so far as to become a terrible temple for the Dark Gods, the Space Marines will bring about its complete destruction, ending the world once and for all. Retreating to the maximum range of its weapons, a battle barge will launch cyclonic warheads which burn to the planet’s core, blasting it apart from within and removing its imperfection from the Emperor’s blessed sight.

‘It was as though the Emperor himself reached out with a single golden finger and pressed down onto the earth, cracking it asunder.’

- Survivor, Vercessus Cleansing, 864.M40.

The Adeptus Astartes only engage enemy warships on favourable terms, if indeed at all. As has already been noted, battle barges were not built for naval engagements – they lack the long-ranged firepower of larger capital ships and the maneuverability of light cruisers. In void combat a battle barge will rely on its heavier armour to close with enemy ships and launch devastating boarding actions. As it closes, a battle barge can use the weapons batteries that stud much of its hull to rake the enemy with fire. Rank upon rank of plasma projectors, macro-laser cannons, missile racks and fusion beamers fire in diffuse salvos, a co-ordinated pattern of shots designed to strip a target’s shields and overwhelm its close-range defences. With its shields down, an enemy vessel is left open to a teleport assault. Few ships can survive such an attack, the swift wrath of a squad of Space Marines stalking their corridors and attacking critical systems. It is because of this that an enemy captain will do everything in his power to try and prevent a battle barge from drawing too near to his vessel.

If this form of close-range attack is untenable or proves ineffective, a battle barge can always fall back on its bombardment cannons. While their primary purpose is as orbital support weapons, they can be used to great effect against enemy warships. Though they lack the range of lance batteries and the fast reload times of standard ship-to-ship weapons, they more than make up for it in raw killing power. When magma shells impact upon another ship, they do not crash down through their hulls as they might with a planet’s surface. Instead, they break upon contact, erupting outwards, broiling over the surface of a vessel to strip away its plating and shred its battlements. The immense heat and shrapnel from the resultant explosion confuses automated defence turrets and sensors, allowing the Thunderhawk gunships and boarding torpedoes launched from the battle barge to close unharmed. A series of concurrent blasts is enough to knock an enemy ship off course, and a sustained assault from a bombardment cannon can cripple and blast apart even the largest of capital ships.

It was madness. I watched from the observation deck as the battle barge cracked and tore. Still it held orbit, firing intermittently, a defiant answer to the torrent of missiles and laser blasts erupting from the surface. The Valorous just waited, waited for the Eagle Warriors it had deployed to be extracted. Even when its shields failed and an explosion ripped a hole through its core, it waited. By the time it broke orbit and turned away, it was as a drifting horizon of fire. Emperor only knows how it was still held together.

We... we thought to re-engage but the risk was too great. Dictum required we wait at the system’s edge for reinforcements.

- Transcribed from the confession
of Shipmaster Gregeo Namn,
executed for desertion 789.M40
Space-Borne Home

Although most Space Marine Chapters have a fortress monastery housed on a moon or world, many do not. These Chapters have been forced into the void by war or cruel circumstance as space faring fleets. To these Chapters, battle barges play an even more important role, forming bastions that carry the Chapter’s legacy and a haven when pressed. Several Chapters are rumoured to possess even larger vessels adapted from the battle barge, or built by some other means.

As of 999.M41, the following Chapters are known to be almost entirely fleet-based, though this record is doubtless incomplete: Imperial Fists, Black Templars, Executioners, Black Dragons, Invaders, Charnel Guard, Minotaurs, Fire Hawks, Lamenters, Mantis Warriors, Relictors, Scythes of the Emperor, Knights of Gryphonne.