Fox News Sunday host Chris Wallace talks his five decades in broadcast journalism, following in the very big footsteps of his father Mike Wallace, what he’s learned from interviewing 7 different U.S. Presidents, and what it was like to date Walter Cronkite's daughter when he was a 16-year-old intern at CBS News.  Then he discusses his new book Countdown 1945: The Extraordinary Story of the Atomic Bomb and the 116 Days That Changed the World.  He reveals how Harry Truman agonized over the decision to use the atomic bomb, the surprising dissenter among his military generals who warned against it, and how Truman broke the news of the bomb to Joseph Stalin.  He shares how the U.S. government managed to keep the enormous Manhattan Project under wraps, the many unknown variables that weighed on everyone involved in the mission, and his own touching experience of visiting the Enola Gay with an 80 year old Japanese woman who survived the Hiroshima blast. Order Countdown 1945: The Extraordinary Story of the Atomic Bomb and the 116 Days That Changed the World on Amazon, Audible, or wherever books are sold.  See Chris Wallace every weekend on Fox News Sunday and follow him on Twitter at @FoxNewsSunday.  Today's episode was sponsored by Capella University and Kronos HR solutions.