(CNN) The legacy of slavery, the Civil War and its aftermath are much-discussed in American politics, but seldom expansively enough to bring genuine context to them. PBS and professor Henry Louis Gates Jr. address that shortcoming in "Reconstruction: America After the Civil War," a four-hour documentary that weaves together the past with policies and debates that remain much in evidence today.

Abraham Lincoln freeing the slaves "wasn't the end of the story. It was just the beginning," Gates explains near the outset, leading a tour through 50 years of US history, from Andrew Johnson becoming president through the release of D.W. Griffith's "The Birth of a Nation," a cinematic ode to racism -- dubbed by one expert "the cultural apex of Southern redemption" -- that shaped the modern image of the Ku Klux Klan.

In between, "Reconstruction" enlists a host of academics to detail key events of the postwar years and connect policies designed to disenfranchise African-Americans to tactics that are still being widely employed.

Later chapters look at the cultural response within the African-American community, and the disparate views of two key leaders of the era, W.E.B. DuBois and Booker T. Washington, regarding the most effective means of pursuing racial justice.

Many of the policies enacted during Reconstruction conspired to leave blacks mired in poverty, with the fallout from those actions lingering 150 years later. Legislative efforts were augmented by violence and disinformation -- the latter preying upon a relatively gullible, unsophisticated population in a manner, one historian notes, which mirrors the role social media has come to play this century.

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