During World War II, hundreds of thousands of prisoners were worked to death by the Nazis under a brutal system of slave labor in the concentration camps. By 1942, this vast network of slavery extended across all of German-occupied Europe, but the whole operation was run by a surprisingly small staff of bureaucrats--no more than 200 engineers and managers who worked in the Business Administration Main Office of the SS. Their projects included designing and constructing the concentration camps and gas chambers, building secret underground weapons factories, and brokering slave laborers to...