From Wikipedia

Vietnam - Unseen War

War photography captures images of armed conflict and life in war-torn areas, beginning with Roger Fenton's photographs of the Crimean War of 1853-56, in which he was limited by his bulky equipment and the technology of the day, which had not yet developed a method for photographing moving objects.

The photography of war depicts the terrors of war mingled with acts of sacrifice. Different to paintings or drawings of war, photographic images are not easily altered; although in some cases, photographers manipulate the subjects and scenes depicted in a work, resulting in an image that is not completely objective in nature.