Fourandsix.com looks at photo tampering throughout history, with some choice efforts from Mussolini, Stalin, and even the 1960 U.S. Olympic Hockey Team.
Among the exhibits is this shot of General Ulysses Grant:
Some very nice detective work by researchers at the Library of Congress revealed that this print is a composite of three separate prints: (1) the head in this photo is taken from a portrait of Grant; (2) the horse and body are those of Major General Alexander M. McCook; and (3) the background is of Confederate prisoners captured at the battle of Fisher’s Hill, Virginia.
{ Hat tip: Mike Duffy }