In Japan during WW II, some allied airmen were POW in the town oh Hachioji, not far from Tokyo. A photo of one of the airmen being decapitated by a Jap soldier was apparently smuggled out of Japan and was circulated in the USAAF. I believe it was the 5th Air Force that was continually bombing Tokyo. After the photo was circulated, the aircrews were instructed to save one bomb for Hachioji. As a result the city was destroyed completely. I got there about 20 years after and the town had been rebuilt from the bottom up. No mercy.
If it was the picture I’m thinking of, I thought that the decapitated airman was Australian.