On February 19, 1945, Pfc. Gagnon landed on the southeast side of Iwo Jima with E Company, 2nd Battalion, 28th Marines, on Green Beach 1, which was the closest landing beach to Mount Suribachi on the southern end of the island. On February 23, Pfc. Gagnon who was the battalion runner (messenger) for Easy Company, became a part of what was most likely the most celebrated American flag raising in U.S. history.