The pic of troops with Chauchats isn't of Americans. They're Belgians.
The webbing is the late War, British-made pattern with 4 cartridge pouches in a 1-over-3 arrangement, and the cap has a tassel at the front that means it's not the U.S. Overseas Cap but the khaki bonnet de police.
The article isn't attributed, but I hope the author doesn't mind my pointing this out.
"Sometimes things that are not true are included in Wikipedia. While at first glance that may appear like a very great problem for Wikipedia, in reality is it not. In fact, it's a good thing." - Wikipedia.