The Order of the Iron Soul was a quasi-religious group in the City of the Saved, dedicated to the superiority of machines.
It was composed of those Citizens who had been converted (often by force) into cyborgs, then resurrected in the same form. Not all such Citizens were resurrected in machine form, so it may have been dependent on personal preference. The Order was used as a proxy force by the Rump Parliament, seemingly because of links to Cousin (later Godfather) Pinocchio. (PROSE: The Book of the War)