Retired U.S. Air Force Maj. Gen. Charles D. Metcalf, director of the National Museum of the United States Air Force, addresses the Doolittle Tokyo Raiders during a memorial service held in their honor during their 68th reunion held at the National Museum of the United States Air Force, Wright-Patterson Air Force Base, Ohio, April 18, 2010. The Doolittle Raiders' 68th reunion commemorates the anniversary of the Doolittle Tokyo Raid April 18, 1942, when U.S. Army Air Forces Lt. Col. Jimmy Doolittle's squad of 16 B-25s bombed targets in response to the Japanese attack on Pearl Harbor.