This photography was taken during the 1918 Battle of Zonnebeke, Belgium. It shows the infantry in their trenches, while planes fly overhead through the smoke of exploding shells. But this image actually isn’t quite what it appears to be. The photographer, Frank Hurley (most famous for his photography on the early Antarctic expeditions), created this image with an early form of “photoshopping.”
Early photographers did not believe that it was dishonest to alter photographs, and Hurley and others were even willing to stage events after the fact to get the photo they were looking for. This picture was probably created by merging a photo of the infantry with others of planes and explosions, to create the impressive final image.