The Birth of a Nation remains a landmark movie, whatever one thinks of its politics. D.W. Griffith's silent epic is a film about (in 1916, then-recent) history - those rifts and tears in American society that led to the Civil War - that has become a historical artefact in its own right, and which needs to be viewed as such. Note that a film with no explicit violence or sexuality can still land itself a 15 rating from the censors - chiefly for the virulence of its racism. It opens with some paternal, Great War-era pleas for everything that follows to be understood as an anti-war tract, then immediately puts its foot in its mouth with a title card that insists if the blacks hadn't come to America, there'd have been no need for the Civil War.
Typical of the film's muddled thinking is that Griffith is almost right - if we understand the War to have been fought over slavery - but he lays the blame in entirely the wrong place: this opening essentially grumps "if only those Africans hadn't allowed themselves to be imported into America by rich white traders". The first half, detailing the relationship between two families, the Stonemans of the North and the Camerons of the South, still holds up today as a gallop through an especially turbulent period in U.S. history, and Griffith has a real feel for the way the bonds of American (high) society were ripped asunder by war. He also stages extraordinarily detailed battle sequences, and a reconstruction of the burning of Atlanta that must have provided the producers of Gone with the Wind something to work with two decades later, before winding up with the assassination of Lincoln.
The second half, set during the capital-R Reconstruction, is dramatically much less satisfying (it kicks off with too much Lilian Gish in forests and title cards about capital-L "Love"), morally problematic (white actors sport varying thicknesses of blackface) and historically ridiculous, making a villain out of the character Silas Lynch - to modern eyes, an early civil rights figurehead looking to use the power vacuum left by Lincoln's death to raise blacks to the same standing as whites - while treating the Ku Klux Klan at all points as masked, heroic dispensers of justice. In doing so, Griffith replaces the "what did"s of the first half with a succession of "what if"s: chiefly, what if African-Americans came to power, and were the ones doing all the tarring and feathering?
Here we see stirrings of the racially-motivated paranoia that would spring up again in American society with the anti-Semitism of the 1930s and the McCarthy witchhunts of the 50s (and, today, with the phony controversy over the Obama birth certificate); it reaches its nadir in the House of Representatives sequence, with its shoeless, liquor-swilling blackface bozos eating fried chicken while "the helpless white minority" look on, and in a later incident wherein the hero's sister jumps to her death rather than allow herself to be raped by a black soldier. As cinema, it's fascinatingly flawed spectacle; as an illustration of how racism most often stems from fear, and how every history has its bias, it's more or less perfect.
The Birth of a Nation is available on DVD.