Back in 1868, a British company called J. Whitaker & Sons began producing an annual compendium of statistical information about the world; Whitaker’s Almanack has been published ever since, and none has proven more interesting to me than the 1939 edition. It turns out, for example, that despite our penchant for referring to the “Nazi war machine” when describing the Blitzkrieg years , Germany wasn’t all that mechanized. On the eve of war, there were 47 people in Germany for every motorized vehicle; that disparity was even greater in Italy: 104. By contrast, in Britain there were 14 people for...