April 18 marks the 78th anniversary of the Doolittle Raid, in which Lt. Col. James H. Doolittle, U.S. Army Air Forces, and Vice Adm. William F. Halsey Jr., U.S. Navy, led a joint bombing operation on the Japanese mainland aimed to inflict both material and psychological damage upon the enemy following the attacks on Pearl Harbor. (U.S. Air Force graphic by Travis Burcham)