Actually, in a military sense this would be known as a Prussian Collar, rather than a Mandarin Collar ( 19th century Prussia ). However I don’t know if the British Army would have them at the Crimean War, although Florence Nightingale was as unlikely to wear military uniform as 99.99% of women at the time.

And indeed preferred wearing cats in later life.

I don't actually know about that stuff, I just found the tag with one or two pics and since the wikipedia description appeared to match what I was seeing I went ahead with it.

And now that I searched for prussian collar I'd say it's a bit too obscure to be a useful tag.