I am particularly interested in the period before the Normandy invasion. My father participated in a number of 8th AAF bombing missions in what was called the transportation campaign leading up to the US invasion of France on 6 June. I have read many books on US bombing in the ETO and was surprised by the opinions of some authors that the attacks on marshaling yards/rail stations in Germany were of limited value. The contention was that most rail hubs attacked by strategic bombers (B-17, B-24) could be restored to >50% service in 1-2 weeks time. My research skills are not the best, but I remember seeing a quote that said that either Himmler or Goebbels had a dedicated force of foreign/slave labor that could be mobilized quickly and specialized in marshaling/rail bomb damage repair. Their ability to get them up and functioning again was surprising to me. Does anyone know of this reference? I am thinking it may have been an Overy book but I am unsure.