Before there was Photoshop, there was the simple act of creating composite photographs from multiple images. This one in the Library of Congress purports to show Ulysses S. Grant astride a horse, in front of the troops at City Point, Virginia. In fact, it's complied from three separate images. The body and the horse belong to Major General Alexander M. McCook (see below). The head shot comes from the well-known photo of Grant at Cold Harbor. There are some other examples of early photo manipulation here.