Fortuna Balnearis, which means "Fortuna of the Baths", is an aspect of the Roman Goddess of fortune associated with bath-houses as a Goddess of health. She was especially worshipped by soldiers in remote outposts (wonder if that includes Tomen-y-Mur, the remotest of the remote, up in northern Wales) with two of Her other aspects, Fortuna Salutaris ("Wholesome or Health-bringing Fortuna") and Fortuna Redux ("Fortuna Who Brings [Soldiers] Home"). These epithets reflect the concerns of people far from home in what could be hostile, conquered, un-Roman, and therefore "uncivilized" lands.

Roman culture was known for its attention to personal cleanliness and hygiene, and any provincial town that had the means would have built a public bath-house as a sign of its civilized Roman nature. The general layout of a public bath-house could be quite elaborate, with seperate baths for hot, warm, and cold water, as well as rooms for exercise. Bathers would leave their clothes and other possessions on pegs or with servants; but bath-houses were notorious places for theft, and there are many examples of "curse tablets" offered to Deities to punish people who had stolen items from them while bathing. Perhaps Fortuna, as Goddess of luck, was associated with bath-houses in recognition of the vulnerability of bathers, who were not only vulnerable because they were naked, but were often stolen from to boot.

Fortuna Balnearis was especially a Goddess of military bath-houses, reflecting the extra uncertainty and vulnerability of the soldiers stuck way out on the frontiers, often in lands with very different climates like Brittania with its miserable perpetual rain and chill, or with inhabitants who didn't know the first thing about cleanliness; Her other aspects of Salutaris and Redux are concerned with health and bringing the soldiers home in one piece, and it is likely that Fortuna Balnearis was also concerned with the health of the soldiers, especially through the practice of good hygiene.