The 1915 film, The Birth of a Nation, directed by D. W. Griffith, was certainly groundbreaking for several different reasons. The special effects, although primitive by today's standards, were top of the line for their time. If nothing else we can see just how far we have truly come in cinema technology and just how much work it must have taken to put something like this together in the early twentieth century.
Of course the biggest historical aspect of this film is the Civil War plot. I read that this movie originally premiered in Los Angles with the title The Clansman, the novel after which the screenplay was adapted. Although we have also come leaps and bounds in civil rights as well as technology, this film reminds us of how different our society was less than 100 years ago.
Although parts of this film were obviously biased toward certain prejudices and points of view, it is for the most part, historically accurate. This movie follows two different families, one from the North, and one from the South, around the time of the Civil War. It mainly shows two different sons and how their participation in the war affects their families, but more over, one who founded the original Knights of the Ku Klux Klan. Again we see just now different society is today, as the Ku Klux Klan members were portrayed as defenders of "good."
From the point of the film, we see that although the Civil War tore apart friends and families, arguably, the black-ruled, post war South was even more chaotic. Even though this movie was silent, the soundtrack, added later, helped carry the vast array of emotions. Knowing a lot of the events in this movie really happened definitely makes it a great historical piece of cinema. Any Civil Rights or Civil War fanatic should definitely see this film; but, from a purely cinematic standpoint, this is about as early and primitive as Hollywood gets.