 The original title of this film was "The River is Blue" and the  original director was Lewis Milestone. Kurt Weill even wrote music  for the original project that was never used (lyrics by Ann Ronell).  The title was changed to "Castles in Spain," then to "Blockade." The  topic of the Spanish Civil War was politically sensitive and there  is some hint that the upheavals of the original project were due to  the political content of the film.