“All happy families are alike, but every unhappy family is unhappy in its own way.” Maybe we should go back to that maxim about happy and unhappy families at the opening of “Anna Karenina.” To paraphrase Leo Tolstoy, all happy victors in war are alike, but every unhappy loser is unhappy in his own way. Let us consider how wars have ended since the victory of the Allied powers over Nazi Germany and Imperial Japan in 1945. The Taliban, after their uncontested success in Afghanistan, were overjoyed while the U.S.-supported Afghan forces were destroyed, scattered, exiled and imprisoned. In Vietnam,...