While in writing this review, give one paragraph of context about what was happening in the world at the time the film was made(1940s).

While in writing this review, give one paragraph of context about what was happening in the world at the time the film was made(1940s). DO NOT SUMMARIZE the film. Additionally, include information about how this film presents changes in style, acting, directing, cinematography, etc., as compared to the films of the silent era.