Today Loremasters we speak in sombre tones of the Imperium’s weapons of last resort – the world killing Exterminatus-class.
Exterminatus Extremis is the obliteration of a world’s entire population through some form of weapon used from orbit or nearby space.
Exterminatus is the most extreme method of dealing with some form of heresy, corruption or alien infiltration which has taken root within a planet’s population. Accordingly it is only used in the most extreme of circumstances, when the level of corruption a world bears is so monumental that it cannot be wiped out by any other means. The destruction of the entire population is deemed necessary to prevent the contagion from spreading further.
Exterminatus is essentially one of the many tools in the armoury of the Imperium, used in those cases where complete destruction is deemed a better solution than conventional or covert methods. The world in question may have fallen to Chaos worship, or its Imperial government overthrown and replaced by the rule of aliens such as Genestealers, or it may be a non-Imperial world harbouring an extraordinarily powerful and dangerous species of alien. Exterminatus is often resorted to when the world is deemed to be not worth the amount of men and material that would be required to conquer or reclaim it. Exterminatus is very rarely used on planets vital or valuable to the Imperium. It has also been used as a method of denying resources to alien invasion.
The Exterminatus order can be given by any Inquisitor, Space Marine Chapter Master, Lord High Admiral, or Lord Commander. The Imperial Navy usually resorts to mass bombardment. Space Marines prefer to plant a bomb on the surface. The Inquisition has access to more exotic weapons.
Exterminatus Class Weapons
Cyclonic Torpedoes are a category of Torpedo utilized by the Imperium for orbital bombardment of a planet once Exterminatus has been invoked. A wide variety of weapons fit the definition of cyclonic torpedoes, and employ varying means of scouring the world’s surface, from nucleonic fire to raw plasma. Whatever their method of destruction, the effect of cyclonic torpedoes is the same: the complete destruction of all life on the planet, its atmosphere burned away in a storm of fire and its oceans boiled to vapour, leaving it a barren rock.
The only factions within the Imperium known to have these weapons are the Inquisition and the Adeptus Astartes. Sources conflict on to what extent the Space Marines have the authority to declare Exterminatus without the assent of an Inquisitor, but all agree that Inquisitors have the authority on their own recognizance.
Two-stage torpedoes are a more exotic version of the cyclonic torpedo. Though the warhead is still the same, the delivery system is radically different. Instead of exploding on impact, this device will burrow though a planet’s surface with a Melta charge, and detonate at the core. This will destabilize a planet, and will shatter that world in many cases. They are used against worlds that are devoid of atmosphere or biological life, such as Necron Tomb worlds.
Virus bombs are potent weapons of mass destruction, and were commonly used to carry out Exterminatus in pre-Heresy times. In this role they have largely been superceded by Cyclonic Torpedoes, however virus bombs are still retained by some Imperial arsenals.
Virus bombs were used on Isstvan III at the start of the Horus Heresy by Horus to destroy the Space Marines who remained loyal to the Emperor. Virus bombs were used to execute exterminatus as late as 273.M41 on the Stalinvast hive world.
The Life-Eater Virus, as used on Isstvan III and Stalinvast, is terrifyingly voracious, capable of spreading across the entire surface of a planet in a matter of minutes. The virus can penetrate power armour and rebreathers. The virus quickly rots and breaks down anything of biological origin, reducing it to sludge. Jungles and forests quickly rot into lakes of sludge.
The rapid breakdown of organic matter releases tremendous amounts of flammable gas. The gas eventually ignites, either on its own or with the intentional insertion of an incendiary device, into an apocalyptic, planet-wide firestorm, searing the planet’s entire surface to bare rock, as well as burning the atmosphere of all oxygen.
The Atmospheric Incinerator Torpedo uses an advanced plasma device that bursts in low planetary orbit and literally ignites all oxygen on a target planet. This method of exterminatus was used on Medusa IV in the Medusa system after it was determined to be too difficult to reconquer from the forces of Chaos that erupted from Van Grothe’s Rapidity despite the presence of the Ultramarines second company. It is said that the planet’s surface was melted to glass and that the entire world burned like a piece of amber in space even a month after the attack had been launched.
Modalis-Class Atmospheric Missiles are the most powerful type of Imperial Phosphex Weapons. Used only in extreme instances where Exterminatus is required, a salvo of several Modalis Atmospheric Missiles from orbiting warships will blanket an entire world in deadly Phosphex. The resultant firestorm of green mist will eat away at every carbon-based element on the planet, rendering it uninhabitable.