“The use of the atomic bomb, with its indiscriminate killing of women and children, revolts my soul,” he wrote. “The only difference between this and the use of gas (which President Franklin D. Roosevelt had barred as a first-use weapon in World War II) is the fear of retaliation.” Those harsh words, written three days after the Hiroshima bombing in August, 1945, were not by a man of the American left, but rather by a very prominent conservative—former President Herbert Hoover, a foe of the New Deal and Fair Deal. In 1959, Medford Evans, a conservative writing in William Buckley’s strongly...