Do Sisters of Battle ever retire? I realize people in the Imperium can live to be quite old but that's mostly reserved for the heroes and the very wealthy. What about the rank and file, and especially the rank and file in cultures like the Soritas where they were always groomed for war?
- I think retirement has a different meaning in 40k...
- By our standards, no.
- By their standards, yes?
So full disclosure I have not read the book but after more research into this the book "Cain's Last Stand" by Sandy Mitchell could hold the answer. Lexicanum states that both Ciaphas Cain and a Sister named Julien (a former Celestian of the Order of the Bloody Rose) were retired and assigned to the Schola Progenium on Perlia. The only thing that confuses me is that it mentions both retirement and assignment.
Don't tell black library, but I found a PDF online of what looks to be the full book without the flash... I jumped around looking for: retire and assign. I will preface this for my answer by stating that Ciaphas thinks he is retired although he has been assigned to instruct at a Schola. While he had retired from the battlefields, the dupe was actually just reassigned.
By this point I'd been living on Perlia for around six years, off and on, enjoying what was supposed to be a peaceful retirement. From time to time it actually had been. To my vague surprise I'd quite taken to the role of pedagogue, and the young pups I'd been put in charge of at the schola progenium someone had seen fit to found there since my last eventful visit were a great deal less troublesome than a Guard regiment. - CHAPTER 1
So Ciaphas was assigned to his new posting. That said, given that "There is only war" it is possible that one would consider leaving the battlefields behind for classrooms and desk jobs a full retirement.
There is also mention in the beginning of chapter 5 of a couple Commodores that were retired and in charge of some Stormtrooper cadets.
Towards Julien herself however it seems to introduce her as such:
...Sister Julien, the battle-scarred Celestian veteran in charge of the Sororitas novitiates, [said]... - CHAPTER 5
I could not find any mention of her retirement to the posting, but as at least one Inquisitor is 'retired and assigned' there, a couple of Imperial Guard officers are 'retired and assigned' there, I do not think it a stretch to think she is 'retired and assigned' there.
Lexicanum states that in chapter nine somewhere is where the book says she is retired, but i did not find a single mention of retire in that chapter (or any other) when it comes to the Sister herself.