A GIFT FROM OUR GRANDFATHERS
At the bottom of the photo (click to enlarge) it says:
"Human Statue of Liberty", this image was taken at Camp Dodge in Iowa and used eighteen thousand men.
Col. Wm Newman, Commanding.
No date was given, however, the email this came in said it appeared to be WWI uniforms.
**I found the website that covers the history of this photo. There are other amazing photos too.
Hat tip: The Radio Patriot via Nathan of Orlando.