On a post-doctoral research mission nine years later, Zinn visited the resort near Bordeaux where he interviewed residents, reviewed municipal documents, and read wartime newspaper clippings at the local library. In 1966, Zinn returned to Royan after which he gave his fullest account of that research in his book, "The Politics of History". On the ground, Zinn learned that the aerial bombing attacks in which he participated had killed more than a thousand French civilians as well as some German soldiers hiding near Royan to await the war's end, events that are described "in all accounts" he found as ""une tragique erreur"" that leveled a small but ancient city and "its population that was, at least officially, friend, not foe." In "The Politics of History", Zinn described how the bombing was ordered—three weeks before the war in Europe ended—by military officials who were, in part, motivated more by the desire for their own career advancement than in legitimate military objectives. He quotes the official history of the U.S. Army Air Forces' brief reference to the Eighth Air Force attack on Royan and also, in the same chapter, to the bombing of Plzeň in what was then Czechoslovakia. The official history stated that the Skoda works in Pilsen "received 500 well-placed tons," and that "because of a warning sent out ahead of time the workers were able to escape, except for five persons."The Americans received a rapturous welcome when they liberated the city.