During the Second World War, American and British air-campaign planners attempted to force the Nazi war machine into collapse by attacking crucial links in Germany's national infrastructure. According to the theory, hitting well-selected individual targets would paralyze entire systems. So, at an enormous cost in lives and aircraft, we went after German rail junctions and ball-bearing plants, engine factories and Romanian oil fields.

http://www.armedforcesjournal.com/2006/04/1813800