Joe Rosenthal's 1945 photograph of U.S. troops raising a flag in Iwo Jima during World War II remains one of the most widely reproduced images. It earned him a Pulitzer Prize, but he also faced suspicions that he staged the patriotic scene. While it was reported to be a genuine event, it was the second flag-raising of the day atop Mount Suribachi. The first flag, raised hours earlier, was deemed too small to be seen from the base of the mountain. Look back at other photographs that have helped define modern history.