Fenton went to the Crimea at the urging of Prince Albert and the Duke of Newcastle (who was the war secretary) to document the conflict. The question remains whether it is ethical for a photographer to alter a scene. It was the second photo which appeared in newspapers of the day and other publications. Altering the scene certainly diminished its historical value. This is what bothered Susan Sonntag. It also puts into question all his other photographs.
The following site describes the situation in more detail. http://en.wikipedia.org/wiki/Roger_Fenton