This is the first of two stories written by Rod Serling to involve the sinking of the RMS Lusitania. The second was the "Lone Survivor" segment of Pamela's Voice/Lone Survivor/The Doll (1971).
Dana Andrews played the protagonist, Paul Driscoll, in this episode while his younger brother Steve Forrest played the protagonist, Major Robert Gaines, in the succeeding episode The Parallel (1963).
Originally intended to open with Paul Driscoll and his mentor Harvey having a political discussion, but was judged too boring before the final cut.
This episode takes place in 1963, in Hiroshima, Japan on August 6, 1945, in Berlin, Germany in August 1939, aboard the RMS Lusitania off the Old Head of Kinsale, Ireland on May 7, 1915 and in Homeville, Indiana from July 1 to July 3, 1881.