"Beware beauty as much as you fear the hideous, for beauty may hold you in contempt and destroy you after it lulls you into a false sense of contentment."

—Grand Missionary Agnar Clavan

Mackensee is a Feral World within the Jericho Reach, far from the salients of the Achilus Crusade.

By all appearances, Mackensee should be a paradise for Humanity. Its climate, gravity, atmosphere, and native life forms are all well suited to Human habitation. Every exploratory craft that has surveyed the world has ranked the planet as an ideal candidate for colonisation efforts.

In spite of that, during the height of the ancient Jericho Sector before the onset of the Age of Shadow, repeated attempts at colonisation all met with disaster. Ironically, the Tyranid forces of Hive Fleet Dagon seem to be having little better luck as they attempt to devour the world for their own purposes.

Legends suggest that psychic echoes of those who first visited the world yet defend it, but xenos forces are at work, attempting to hold the world against any who might take it from them. In truth, it is an Aeldari Maiden World under siege.


Over the course of the 33rd and 34th Millennia, there were at least four discrete attempts to colonise Mackensee. The world's ideal climate, abundant natural resources, and stable planetary conditions all made it an ideal candidate. From an initial review, only its location, far from the more civilised worlds of the Jericho Sector, made it seem like a poor choice.

However, many potential colonists viewed the relative isolation as a significant asset, hoping to find a place where there would be a minimum of oversight and interference.

In each of these instances, the initial landings went well. Colonists quickly established enclaves and began the process of taming the wilderness. By all accounts, the world was receptive to each attempt. Agricultural efforts using plants and animals of Terran lineage seemed well-suited to flourish on this new world.

Reports were sent back to the colony's sponsors indicating that initial signs suggested tithing might begin well ahead of schedule.

None of these attempts reported any unforeseen difficulties, and all noted that they were capable of making use of the world's abundant resources much sooner than expected, minimising the requirements to import additional supplies.

Unfortunately, every one of these attempts later met with disaster. The entire population of the first effort died to a previously unknown native infection, their bodies discovered only when a supply vessel arrived.

The second colony was destroyed when a previously unknown fault-line gave way and the entire enclave sank deep beneath the world's oceans.

The third colony inexplicably vanished, leaving no trace of their existence behind. Repeated investigations into its disappearance have yielded no clues, though ancient records suggest that theorists on many of the worlds within the Jericho Sector had explanations.

There have been no further attempts at colonisation since that time, as the sector began its descent into the Age of Shadow shortly thereafter.


Once the Jericho Sector collapsed, there were few Human institutions capable of attempting to establish a colonial outpost. As the world lacked any known sentient inhabitants, there is no record of any activity on this isolated world.

However, those who dwelt within the region did not completely forget about Mackensee. Several cultures have legends of a deserted Paradise World where people might flee to escape the collapse of their homes.

It is believed that more than one cult leader may even have assembled people and taken their precious resources to lead a colonial expedition to just such a paradise. If so, it is clear that none of these efforts ever amounted to a successful mission.

In all likelihood, such hucksters either stole the assets or were exposed and suffered their just punishments. It is possible that one or more small groups of nobles might have launched an expedition with the last of their dwindling reserves, but if this was attempted it met with failure.

Alternatively, a force affiliated with the Ruinous Powers might have travelled to this world and turned it into a corrupted pit of despair, but no traces of such efforts remain. Ultimately, there is absolutely no concrete evidence that any Human groups have ever successfully established a foothold upon the world.

Instead, by all appearances, Mackensee's natural resources were left fallow for millennia. During this time, even the remains of those who had once attempted to tame this beautiful world deteriorated into dust.

While it is possible that a xenos group might have visited the world at this time, there is no known evidence to confirm their intrusion. If such an effort was made, it clearly met with the same results experienced by Humanity millennia earlier.

The 41st Millennium

In 652.816.M41, a vessel carrying desperate refugees from Pilgrim's Loss arrived in the Mackensee System. The voidcraft represented the last desperate efforts of a small outpost that had fled before the Tyranid forces in that system. Upon their arrival, they were horrified to discover that this world was also under assault by Hive Fleet Dagon.

Rather than attempt to land within the system, they immediately fled once more, travelling this time to Beseritor, where they were able to report the attacks to Imperial authorities -- both Pilgrim's Loss and Mackensee were under the influence of the Shadow in the Warp; communication from both locations was impossible.

The Deathwatch intercepted the reports that were sent on to Achilus Crusade High Command. In order to identify the full extent of the Tyranid infestation, Watch Commander Mordigael immediately dispatched a Kill-team on a reconnaissance mission to Mackensee.

By the time of their arrival, it had been more than six solar months since the pilgrims initially visited the world. To their tremendous surprise, they discovered that the invasion force had made very little progress in its efforts.

The Kill-team's visit to Mackensee was necessarily brief. Their mission was to quickly survey the world and identify the stage of Tyranid progress, so that a decision could be made about the viability of future engagements. A consequence of their quick assessment was that they missed a critical point of analysis.

Aeldari Pathfinders -- of Craftworld Alaitoc -- had actively defended the world from Tyranid assault. Mackensee is a Maiden World, which waits in pristine isolation for the day when the Aeldari might have a need for it.

These Asuryani fulfil their duty to protect the world from Tyranid incursion just as their ancestors defended it against Human colonists.

However, the Aeldari's reserves are limited. It is unclear how long they can resist the boundless hunger of the Tyranid invaders.


By virtually any measure, Mackensee's natural environment represents a world that could easily become a paradise for any Humans fortunate enough to enjoy it. The soil, air, and water are all free from toxic contaminants. The oceans have a salinity level very close to that of ancient Terra's.

The world's temperate zones are broad and filled with ample water. Its life forms are largely compatible with Human biochemistry, such that the flora and fauna are almost all non-toxic and even well-suited to the Human palate.

Mackensee's seasons are relatively mild and her ecosystems are all quite stable. In short, any Humans fortunate enough to live upon the planet would have very little reason to ever wish to leave it.

Mackensee's oceans are vast, covering more than half of the world's surface. While there are two large continents, a substantial portion of the world's surface area is made up of island chains. Most of these islands are spread within the planet's temperate and tropical zones, and represent more than forty percent of the planet's arable land.

These regions enjoy the constant, gentle breezes from her oceans as well as lengthy growing seasons. The second and third Mackensee colonisation attempts targeted island chains within this zone.

Most of the world's large plants, which are analogous to the forests of ancient Terra, are located upon the continents. The first and third colonial efforts targeted continental regions, with the intent of harvesting these plants for the early stage construction of their enclaves.

According to initial reports, the woods were hardy and resistant to the planet's weather even after harvesting. They also appeared to be well-suited for use with STC techniques, according to preliminary reports generated as part of repeated exploratory efforts.

There are two endemic threats on Mackensee, both of which present challenges to Humanity. Neither of these are insurmountable, but both must be considered. The first is the world's microbiology.

The world's moist air -- particularly near its oceans -- contains a broad range of microbes. While the vast majority are harmless to Humans, a small subset can become extremely effective parasites.

Of these, an even smaller portion is capable of inducing severe illness, which can lead to death if left untreated. Standard medicae protocols can easily overcome this threat, but such equipment is not always available to an isolated colony.

The second major threat includes a number of Mackensee's top tier predators. Just as Humans are capable of feeding upon the native flora and fauna, these aggressive xenoforms are equally capable of surviving a meal of Human flesh.

The threats vary substantially across the world's surface, as different organisms seem to have adapted to the role within its varied ecosystems.

However, most are fast moving, strong, extremely aggressive, and quite hardy. Many are also arboreal creatures, which are prone to launching swift attacks against prey on the ground. None of the known species are resistant to weapons fire, but all can represent a significant threat to an unprotected and unprepared Human.

Of course, the gravest of current threats is not from the world, but instead the one imposed by the Tyranid swarm. As these xenos continue to intrude upon the system, they have spread their foul Mycetic Spores upon its surface.

Though the invasion appears to have stalled at a relatively early stage, their mark is present in many of the biomes across Mackensee's surface and deep below it as well. Dozens of capillary towers have already emerged.

Seismological surveys can quickly reveal subterranean activity, the sky is often filled with Gargoyles, and there are portions of the planet where all of the native life has been eradicated.


The Aeldari of Craftworld Alaitoc have defended the world of Mackensee -- a Human designation -- for millennia. Once a barren rock, in times long gone the Aeldari seeded it, so that it could eventually develop into a world well-suited for colonisation by their species.

Long ago, it completed its transformation, turning into one of the undisturbed Maiden Worlds reserved for use by the Aeldari civilisation. Those of Craftworld Alaitoc see this planet as a portion of their birthright and defend it so that someday their descendants might be able to use it as their long-dead ancestors foresaw.

Due to the stringent nature of Aeldari culture, there are many individuals who turn away from its rigid path system. Those who leave their craftworld, often to explore the galaxy, are known as Outcasts.

Rangers are a subset of Outcasts, who travel the Webway freely but maintain an allegiance to their craftworld. In times of conflict, Rangers often assemble to scout out enemy fortifications and disrupt enemy forces from concealment.

Their skill is such that Aeldari Aspect Warriors are often able to overcome their opponents much more quickly when working in conjunction with Rangers.

A subset of Rangers become so devoted to the Path of the Outcast that they become lost upon it, just as Exarchs or Farseers become lost upon the Path of the Warrior and the Path of the Seer. These Pathfinders become masters of concealment and incomparable snipers, through application of abilities that may be based upon the race's inherent psychic nature.

A small group of Pathfinders, in conjunction with a much larger group of Rangers, have maintained the responsibility of defending Mackensee against all attackers. It is their expertise that led to the failed Human colonial efforts. They have also worked tirelessly to stall the Tyranid incursion upon the world.

Their resources, however, have begun to flag against the untold hordes of encroaching xenos. Though their successes to date are impressive, unless the craftworld begins to contribute additional resources to the world's defence, the future remains uncertain.

As the Aeldari continue to oppose the invasion with precision and through carefully executed plans, the Tyranid presence appears to have become terribly disjointed. Normally, Tyranid assaults proceed in a systematic fashion. Different bioforms appear at various stages in the process.

Each new creature emerges to exploit opportunities created by the activities of those that have come before. This reproduction scheme is highly ordered and systematic, though it can be modulated by the actions of the controlling Hive Mind.

The assault on Mackensee has not been consistent with such an orderly assault. Lictors and Genestealers arrived on the world and successfully contacted the Hive Mind to send its fleet to the system, but these xenos were all but exterminated by Pathfinders prior to the hive ship's arrival.

As the first wave of Mycetic Spores rained down upon the planet, Aeldari troops were in place to eliminate many of these intruders even as they arrived. As a consequence, the Tyranids squandered a large portion of their reserved biomass during the early stages of the invasion.

Without a solid foothold, Tyranid forces were unable to quickly devour additional biomass from the targeted world. This led to reduced numbers of Gargoyles, Gaunts, and even capillary towers. Even as these began to emerge, the Aeldari pressed their advantage and eliminated many of the first creatures to emerge.

With few capillary towers to transport biomass back to the ships of the fleet, they were soon unable to contribute additional Mycetic Spores to the invasion.

Recently, additional void-capable Tyranid bioships have been directed towards the Mackensee System. It is likely that these massive creatures are supplied with resources that can be committed to renew the invasion.

If these forces join in the assault, it could break the stand-off that has existed between the opposing xenos for most of the past standard year.


  • Deathwatch: The Outer Reach (RPG), pp. 79-82
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