Lots of people don’t believe in second acts, second lives, mid-life resurrections. As F. Scott Fitzgerald put it in The Last Tycoon, published in 1941: “There are no second acts in American lives.” But his absolutism was being embarrassed at that very moment: 1941 was also the year that Dwight D. Eisenhower became a late bloomer. Before the war came to America, Eisenhower had thought he would retire, without ever having seen either war service or getting a chance to exercise his talents...