Red Cross flag, WWI,WWII,German, US???

[Hummel]

Hello,

I have had this for several years. I got it because I liked it and it was not over priced. I was told it was WWI German.... but I know it can probably not be confirmed as either WWI,WWII,German or U.S..... or can it? What do you guys think by the multi piece construction, metal grommets and the darkened “white”?
I know it is a long shot for dating this flag but give me your educated guess please.

Thanks,
Hummel