Trailer, 'The Birth of A Nation,' (1915) epic silent film by D.W. Griffith impacted racial segregation, reinforced white supremacy and contributed to the rebirth of the KKK. (Full Film online).
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Wiki, Ed. - The Birth of a Nation, originally called The Clansman, is a 1915 American silent epic drama film directed by D. W. Griffith and starring Lillian Gish. The screenplay is adapted from Thomas Dixon Jr.'s 1905 novel and play The Clansman. The film has been acknowledged as an inspiration for the rebirth of the Ku Klux Klan, which took place only a few months after its release.

The Birth of a Nation is a landmark of film history, lauded for its technical virtuosity. Its plot, part fiction and part history, chronicles the assassination of Abraham Lincoln by John Wilkes Booth and the relationship of two families in the Civil War and Reconstruction. It was the first motion picture to be screened inside the White House, viewed there by President Woodrow Wilson, his family, and members of his cabinet.

The film was controversial even before its release, and it has remained so ever since; it has been called "the most controversial film ever made in the United States" and "the most reprehensibly racist film in Hollywood history".The film has been denounced for its racist depiction of African Americans.
The Ku Klux Klan (KKK) is portrayed as a heroic force, necessary to preserve American values, protect white women, and maintain white supremacy.

The film's success was both a consequence of and a contributor to racial segregation throughout the U.S. In response to the film's depictions of black people and Civil War history, African Americans across the U.S. organized and protested. In spite of its divisiveness, The Birth of a Nation was a massive commercial success and profounfly influenced both the film industry and American culture...
https://en.wikipedia.org/wiki/The_Birth_of_a_Nation