We can thank Robin for this gem! She’s got quite the keen eye when it comes to spotting unique sets of photos at antique sales & militaria shows. We don’t know which maneuvers this is from, but we guess they may be from the Louisiana Maneuvers in 1940 or 1941.
Here’s a start for your research into the Louisiana Maneuvers.
Also, if you wonder how the Army judged the maneuvers, you can learn how they did in in FM 105-5 The Umpire Manual. This one is dated 1944, but it’ll basically be an improvement on the rules used during 1940-1941.