As photography evolved, one theme remained fairly constant in the public’s opinion: seeing is believing. People generally regarded photographic prints as evidence of truth and reality. Steadily becoming more mobile, photographers tended to photograph scenes of current events wide, because as much visual information as could be jammed into a photo, the better the photo was considered. A tight crop didn’t give the viewer nearly as much information to digest as a wide shot. It was believed there was more truth and accuracy in wider shots than close ups.
However, despite advances in technology, many photos still took multiple seconds to expose. This limited how much a photographer could successfully capture of live events, particularly ones involving lots of moving people such as war photography.
Up until the mid-1800’s war was something romanticized and fantasized about. Unless you had been to war, you didn’t know what it looked like. Cameras offered a glimpse into what it was like and given the public’s opinion that photos = truth, many officials in power began to realize they had a great PR tool at their disposal. If they financed a photographer’s work, they could pay him to bring back images that support the views they’re trying to perpetuate. In short, photos were (and still are) a stellar part of propaganda machines.