Iconic images of war and conflict have often changed the public perception of war, and sometimes even the conduct of war itself. The image on the right, showing the exploding "Fat Man" A-bomb dropped on Nagasaki, Japan, on August 9 1945, tells a story of terrible tragedy and suffering without a single word being uttered.

Only those on the aircraft that dropped the bomb, and those on the ground in the immediate area, saw this terrible event unfold. However, the man in the street is able to grasp the horror merely by viewing two or three graphic images. The mushroom cloud seen here indicates the power and scale of the explosion, and a picture of the obliterated city with hardly a structure left standing, probably tells the rest of the story. If not, add a single image of the victims or desperate survivors in the street, and no one needs further explanation. Such is the potential influence in the hands of a war photographer.