They began on a small agricultural world called San Leor.  There were perhaps 500 members when Lord Vandire first heard of them.  The sisters were living as a cult, containing only female members, totally devoted to the worship of the Emperor through inner purity.  They studied the ancient war arts, clearing their minds of all worldly matters, and spending their entire lives honing their skills.

Lord Vandire decided that these warriors were just what he needed to protect himself and his wrong doings, and tricked the sisters into becoming his Ecclesiastical Bodyguard.  Vandire renamed the warriors 'Brides of the Emperor' and had them trained by the best the Imperium had to offer, to combine their considerable skills with the more sophisticated methods of the Imperium.  They killed many innocent people in the name of the Emperor, until one day they were shown something by the Adeptus Custodes that has never been spoken of.  Whatever it was it changed their view of Vandire.   Their leader Alicia Dominica executed Vandire, and they became the Daughters of the Emperor once more.