
Mars itself is not only the Mechanicus' capital, it's one of the most important Forge Worlds in the Imperium, and houses several Titan legions. They are theoretically subordinate to the Imperium, and their highest-ranking member is one of the twelve High Lords of Terra, but the Machine Cult has its own specialized army, the Skitarii, and run the aforementioned Titan Legions, standing slightly apart from the Imperium of Man despite propping it up. This Mechanicum, later renamed the Adeptus Mechanicus, became a vital part of the Imperium, providing technical expertise, planet-wide factories known as Forge Worlds that produce everything from lasguns to civilian goods, and incredible weapons such as the Titan Legions. When the Emperor was reuniting humanity, he found on Mars a strange priesthood devoted to the preservation of what knowledge remained.

In Warhammer 40,000, Mankind's golden age is long past, and many of its technological secrets have been lost.
