The POWs are wearing US Army brown denim fatigue uniforms, At the time, fatigues were issued strictly for work clothing, the wool service uniform worn by the US troops in the photo serving as both a garrison dress and field service/combat uniform. It was not until WW2 that fatigue uniforms began to be used as a combat uniform, as well as for work duties.

Incidentally, brown denim fatigues are incredibly rare these days and much sought after by military collectors/vintage clothing enthusiasts. This is one of the most detailed photos I've ever seen of the brown denims being worn, and thanks for posting.

It appears that he was a Unitarian from St. Paul, MN. He left a church where he'd accepted a call only in October 1917 to serve with the Red Cross.

https://books.google.com/books?id=7tEZAAAAYAAJ&pg=PA28&lpg=PA28&dq=Rev.+...

I'm somewhat surprised the Red Cross didn't draw more heavily from Lutheran pastors of German descent, who would of course have known the language quite well. It appears Rev. Eliot is doing just fine, however.

Well I don't see any Corporals with funny little mustaches..

The previous poster is either an historian or a time traveler. In either case, thank you for a very detailed account of the photo. I am suitably impressed and grateful.

The Germans are wearing late model American military garrison caps. The earlier version was thin and long and made the wearer look like he had a woodpecker’s topknot in back. Many Doughboys disliked them. The German to the right of center looks like he may be wearing the earlier model. Several P.O.W.s have given up their German leather boots for Doughboy hobnail shoes with leg wrappings. Leg wrappings were comfortable to wear, by the way, although they tended to come undone during long hikes. All but one German has stuffed his trouser legs inside his boots as if still walking in the mud of the trenches. The Chaplain has on a Sam Brown belt which was not American issue, but which officers in France thought looked good and made a private purchase. General Pershing wore one himself, O.K.’d the belt for as long as officers were overseas, although they had to take them off when they got back to the U.S.A. After the war the U.S. military made them a part of the regular Army and Marine uniform.

There are a couple of PWs with Kaiser Wilhelm mustaches, and they're probably going over the wall tonight.