FIRST AID POST...

[Harry Faversham]

How were they marked in the ACW... red cross, like we all know, or a single red flag flying from the tentpole?

[joroas]

I'm unsure, the red cross wasn't founded until 1863, so probably not.

One of the Union flags was a large yellow flag with a large green H on it and the Confederates a large plain red flag.

[Elk101]

I found this image of a Union 'hospital'. It's difficult to tell what colour the flag is, though it appears to be plain and most likely yellow as Joroas mentions. I'm not sure what the diamond shaped marker to the front if the building?

Edit: apparently the 'H' was adopted in 1864, with the plain yellow flag prior to that.

[Elk101]

This may be of interest, it explains the various flags used by both sides:

http://www.crwflags.com/fotw/flags/us%5Ehosp.html

[joroas]

Good hunting, there, so you won't go far wrong with plain yellow flags.....

[Harry Faversham]

Thanks everybody, much appreciated.