Emile de Antonio's 1968 montage Vietnam-War polemic. The original found-footage political documentary.
From Wikipedia
In the Year of the Pig is an American documentary film directed by Emile de Antonio about American involvement in the Vietnam War. It was released in 1968 while the U.S. was in the middle of its military engagement, and was politically controversial. One year later, the film was nominated for the Academy Award for Best Documentary Feature. In 1990, Jonathan Rosenbaum characterized the film as "the first and best of the major documentaries about Vietnam".