Quoting Goldmos, reply 48
The concept of 'medical', 'civilians', or even 'clergy' on the battlefield and exempt from combat is a concept developed late in the Renaissance in Europe when formalized warfare was created (prior to that it was pretty much free game in terms of killing civilians or religious figures) so therefor red cross would not even work since they would have just been killed when trying to help the wounded.
Sorry, my bad 
I did some CPR training and didn't remember the organization that start it all. I thougth it was red cross but my memory failed me and I'm sorry. But, I know there was a group of knigth in the medieval time that was trained with the basic "First aid" treatment to help the other survive but couldn't remember the name of this organisation... but for the other part of your post, I didn't imply that the "red cross" would go for the sanitation, only helping gaining some more HP each turn in a city like if they were in an hospital .
