House Krast was the first of outer non-[[Mars]] Knight Houses House that declared their allegiance with the Imperium - it happened at the start of during the [[Great Crusade]] in 850.[[M30]].{{Fn|4}} Its early allegiance allowed it to be showered with ancient Knight Armours from Mars in return for granting their benefactors access to [[Chrysis]].{{Fn|8}}

The proximity of Chrysis to [[Mars]] meant that the knightly houses of Chrysis were able to swiftly resupply their Knights with new weapons and equipment. Foremost amongst these knightly houses was Krast, and their strength at arms was bolstered further still by their new alliance with the [[Mechanicum]]. Gladly did the full might of House Krast set forth at the bidding of Mars to fight in the [[Emperor]]’s wars, leaving the lesser houses to consolidate the alliance with the Mechanicum on Chrysis. However, the Knight world’s proximity to Mars was to ultimately prove its undoing when the full might of Horus’ traitor forces descended upon Chrysis as he carved a bloody path across the galaxy towards Terra. The Knights of House Krast returned to their planet only to find it devastated and the lesser houses all but erased from existence. Ever since At the end of the [[Horus Heresy]], House Krast had been reduced from 400 Knights to just 100, with those who survived swearing oaths of vengeance against the Traitors.{{Fn|8}} Ever since the Heresy, the Knights of House Krast have vowed that whenever the threat of [[Chaos]] rears its malformed head, they will be there to sever it at the neck.{{Fn|1b}}