This era must have been "golden times" for professional/officialy allowed photographers! And must have lasted till the end of the interbellum. The system (also now) existed in taking a picture of as many persons as one could "round up", everyone was/is interested in seeing his image on a photo, and everyone of them is "a possible sale". It makes me think of the British poet/writer (the name escapes me right now, Byron???) who once wrote: "It's good to see one's own name in print!".And only one soldier has a gas mask, it was forbidden for a soldier to have a camera in the front lines, if caught with one, it counld be a charge of spying.