When the Germans broke through the Maginot Line, in June 1940, and poured down through northern France, sending some 14 million terrified Dutch, Belgians and French onto the roads going south, many of pre-war Paris’s American residents were still living in the city. Some joined the exodus south and never went back. A few were taken prisoner. Others lay low and awaited events. And when the mayhem died down, 5,000 or so American citizens decided to remain in the city that they had made their home.