→History of the Adeptus Mechanicus
The Mechanicum only lasted till midway through the Heresy. Loyal tech magi were evacuated from Mars when the Death of Innocence hit the planet and a new Fabricator General was elected. This posed a bit of a problem for the Mechanicum as a whole as the previous Fabricator General was technically still the head of the Mechanicum and still held Mars. Various allied and vassal parts of the Mechanicum had a legal meltdown as to who they were supposed to be loyal to - the nation they were a part of and technically still subordinate to or the overarching Empire they had sworn fealty to by proxy. Martian loyalists suggested the creation of a new Adeptus to put the Mechanicum on a level playing field with the other sections of the council of Terra, gaining a voice in the running of the Imperium as a whole. The other sections weren't keen on the idea but took the opportunity to roll other Martian assets into Terra's direct control. The Martian ambassador resolved the complicated Binary Succession issue by literally walking an Imperator Titan right outside the council chambers until the council agreed. Thus the modern Adeptus Mechanicus was formed.
They also created a [[Steel Confessors|Chapter]] of [[Space Marines]] meant to be loyal to them over the rest of the Imperium once. The Imperium actually reacted rather well, only taking their toy away instead of smashing the fuck out of every Forge World and mind-raping every Tech-Priest and servitor involved, which the Imperium is fully capable of doing but it wouldn't be worth nearly the effort unless something extremely stupid happened.
== The Machine Spirits ==