John Capa's photograph of the death of a militiaman fighting Franco's rebel troops in 1936 - entitled The Falling Soldier. It is apparently a defining photograph in the history of photojournalism.

There is a little bit of controversy as to whether or not the photo is staged. It looks real(ish) to me. It looks like there is a wound to the head. Also it is a strange pose to be in if you were to stage the picture. I've got to say that the guy probably wasn't best advised regarding his wardrobe - white shirt on a landscape is quite conspicuous. However maybe that highlights that the civil war was indeed fought by ordinary folk.