During the height of the wars in Iraq and Afghanistan, the Pentagon launched a controversial counterinsurgency program called the Human Terrain System. The program embedded social scientists within military units to provide commanders with information about the cultures and grievances of local populations. Yet the controversy it inspired was not new. Decades earlier, similar national security concerns brought the Department of Defense and American social scientists together in the search for intellectual weapons that could combat the spread of communism during the Cold War. In Armed...