Arkhan Land was one of the most important techpriests the Adeptus Mechanicus have ever had in their ranks. Considered a genius (if quite eccentric man even by the AdMech's standards) by every other member of the Machine Cult, he is responsible for some of the greatest technological advances during the time of the Great Crusade. How big is his contribution to the Imperium, exactly? Every vehicle the Imperium uses with the word "land" on them directly comes from his work. That's right, it's not because machines like the Land Raider, the Land Crawler or the Land Speeder (and its many later derivates) are vehicles that work on land, it's because they were named in his honour. Why they weren't named Arkhan is a mystery in universe, but out of universe it's probably to avoid association with the second spookiest skeleton in Warhammer Fantasy.
Early life and the expedition to the Librarius Omnis
Even during his early years, Arkhan Land was considered a brilliant individual. Fluent in many tech-languages before his childhood had ended, he quickly rose on the hierarchy of the Mechanicum, even if he rejected many of the popular body-enhancements the Mechanicus are famous for aplying to themselves, to the point of looking like an actual person, rather than an amalgamation of many pieces of machine stuck together over the framework of a human). However, his fame would not really explode until his expedition to the Librarius Omnis.
The Librarius Omnis is a massive region located somewhere below the forgotten catacombs of Mars. It's a massive, continent spanning area filled to the brim with old tech, and as such, it has attracted an immense amount of techpriests and explorers to it, trying to uncover rests of old technology. However, it also guards many dangers, and the practical majority of people who go in search for this legendary place never really reach it, and much less come back. During the early days of the Great Crusade, Land organized an expedition in search for a fully functional STC, and after three years of exploring the place, and after many considered him lost to the unknown, he came back with some of the biggest discoveries done in the history of the Imperium.
Arkhan Land's discoveries and later work
While he did not find a fully functional STC, Land was able to bring to light a massive amount of lost knowledge, which would quickly become part of the backbone of the logistic structure of the Imperium at large. Land's discoveries can be divided into three:
- The first discovery was an almost complete schematic of a battle tank, which served as the basis to create the Land Raider. While it was one of the best designs the Imperium had at the time, the necessities of the Great Crusade forced Land to deviate from the standard to adapt it to the needs of astartes. After all, the original creators of the Land Raider had regular humans in mind, not hulking behemoths in power armour, so he had to adjust the design to Space Marine's size and weight. Following this principle, the Spartan Assault Tank was created from the blueprints of the Land Raider. It is also possible that many other tanks were modified to include some of the improvements discovered with the Land Raider's blueprint. Land was infamously blase about the tank, referring to it specifically as Land's Raider or the Raider pattern tank. The pedant wrote a huge essay about the importance of the difference.
- The second discovery was a series of remainings of anti-grav technology from the DAoT. While this was not an STC in the strict sense of the word, Land was sensible (or irresponsible, depending on whom you ask) to just reverse engineer this pieces. By doing that, he discovered many of the fundamental principles of anti-gravity technology, so he was able to apply it to many imperial designs, from civilian to militar. Jetbikes and Land Speeders owe their existence to this, and while most of the heavy uses of Land's anti-grav tech was seemingly lost during the Horus Heresy, Archmagos Cawl's designs for Primaris Vehicles such as the Repulsor Tank or the Astraeus Super-Heavy Tank heavily hint to a rediscovery of Land's ideas (considering Land and Cawl were alive at the same time, and also that Cawl has brought many other things from the early days of the Imperium, as well as the miraculous developement of the Primaris Marines, he could have improved Land's ideas. Either that or he copied Eldar anti-grav tech, you make the call).
- The third major discovery was the Land Crawler. While this was in theory just an agricultural vehicle, the efficiency, reliability and easyness of production of this vehicle basically keeps the Imperium alive. The food production of the Imperium would be a fraction of what it is now without the effords of this vehicle, and many consider it Land's greatest contribution to Mankind. The design has also been applied to many war vehicles, specially in roles such as troop transport and the like, but also as a more traditional combat vehicle.
This discoveries catapulted Land into becoming the most famous figure in the whole Mechanicum, even if he never really became Fabricator-General - partly because he was insufferably arrogant and contemptuous of anyone who wasn't as clever as him (and kept pissing off more senior members of the Mechanicum). While these are his most important works, he also had his hands on other projects, such as the development of the Mars Universal Land Engine (or M.U.L.E.), which was inspired in the movement of ancient terran insects to create the Onager Dunecrawler. He was also requested by the Emperor Himself to study Angron's Butchers Nails, how they function and if there was any possible way of removing them. In this endeavour he failed, being unable to find a way to cure Angron from this device.
Land during the Horus Heresy
Arkhan Land firmly stood with the loyalists during the civil war, seeing the Emperor as the Omnissiah himself, while also respecting him as the greatest scientific mind there has ever been. Land became embroiled in the first moments of the Death of Innocence events in Mars, although he was one of the priority targets for both sides (the traitors could not leave a mind as brilliant as Land's to undermine Horus' plans, whereas the loyalists needed as many big Mechanicum personalities to keep the war efforts), and he was saved by an Imperial Fist rescue party. He was busy during the war improving the armoury and vehicles of the Adeptus Custodes, hence the many anti-grav vehicles they and the Sisters of Silence have, and even accompanied them to the War on the Webway. That event kinda traumatized him, seeing too many daemons for a sane mind to comprehend, though he never went mad or corrupted.
After the Heresy was done, he organized a second expedition to the Librarius Omnis, due to many technologies becoming lost or corrupted during the war. Trying to recover as much as possible like he did the first time, he organized a massive expedition with whatever Mechanicum resource he could find, but this time he didn't come back. His diaries were discovered two centuries later, which hint at him and the rest of his expedition being slowly killed by an unknown entity under the catacombs of Mars.