Visual style / Social commentary

While Stagecoach (John Ford, 1939) “appears to glorify American history, particularly its expansion westward at the expense of Native Americans” (Bernstein 319) it also develops an “acute social observation” of life on the frontier and it challenges elements of the myth constructed around this history (336).
Explain Bernstein’s claim.
What are the main points of Ford’s commentary on society and how does he develop them with his use of mise-en-scène and cinematography?
In other words, focusing on specific techniques of mise-en-scène and cinematography, select and analyze a few scenes or shots that for you best exemplify the distinct visual style the filmmaker designs to develop his social observation.