Robert Wise had already made West Side Story when he was approached to direct The Sound of Music. One of Wise's initial contributions was to ensure that the sentimentality and sweetness be removed from in order to create a film that was based in a very realistic tone. This would add to the conflict of the Nazi regime in the film that pervades throughout as their power is growing in Europe and will eventually spill directly into the home of the Captain, his family and Maria.
Another major influence that Wise had upon the film was in casting it. Julie Andrews was a top choice, but after he and screenwriter Ernest Lehman saw footage of Mary Poppins (yet to be released at that time), Wise immediately made an offer to her as her talent was obvious to him. Wise's choice of Christopher Plummer came after seeing him on Broadway. Plummer would turn the role down multiple times, but Wise heavily pursued the actor as he knew that he was the choice. And this lead to a character that was fully realized as Plummer, with Wise on his side, added humor to the role of the strict Captain.
Wise's use of location is quite apparent, even from the opening scene with Julie Andrews singing in the wide open mountainous land in Salzburg, Austria. The use of sets was quite common for musicals so, adding the rich imagery of the land connects the audience to the time prior to the Nazi occupation as well as to the grandness of Maria's expression through song. These things all led to the film becoming the biggest box office earner in history for five years, and continuing to be a beloved classic film to this day.
