I don’t know how many people have ever heard of this, and I think it might serve as an interesting example for what people think photography can do and what it then turns out being unable to do. In 1924, German pacifist Ernst Friedrich (who had refused to participate in World War I and had gone to jail for this) published Krieg dem Kriege, which was eventually translated into 40 different languages. It contained photos taken during what people to this day call “the Great War”, with the most gruesome photos being included on purpose. The idea was that viewers would be so shocked by what they saw and that thus war would become a thing of the past. It was a noble idea.
PS: Robert Phillips pointed the following out to me: It’s quite interesting to compare Krieg dem Kriege’s trench photos, such as this one (note the text on top of the photo was part of the book) with Jeff Wall’s (staged) ‘Dead Troops” and Luc Delahaye’s (real) ‘Dead Taliban’.