The sesquicentennial of the Emancipation Proclamation’s signing is one reason to look back at the uphill battle of the movement to end slavery in the United States, and Steven Spielberg’s hit film Lincoln is another. But the movement’s significance to our history alone makes it a worthy subject for the three-part American Experience documentary launching Tuesday on PBS.

The Abolitionists, written and directed by Rob Rapley, is a barely adequate documentary blending archival images with minimally convincing re-enactments. Fortunately, the content outweighs the weakness of the filmmaking.

Rapley’s film focuses on several key members of the abolitionist movement, including author Harriet Beecher Stowe, radical activist John Brown, former slave Frederick Douglass, South Carolina belle Angelina Grimk, who broke with her slave-owning family, and William Lloyd Garrison, who created the anti-slavery newspaper The Liberator as a platform for his deeply held views.

From the first days of the new republic, slavery was a complicated and complicating practice. By 1820, there were some 2 million slaves in the United States and slavery itself was known as “the peculiar institution.” As the abolition movement grew as a human rights battle, it became not just about slavery, but about race as well. And no matter how many people were drawn into the movement’s ranks, it ran up against an even more powerful cultural opponent—economics—and not just in the South, but in the North as well.

The abolitionist movement was both organized, through the American Anti-Slavery Society, and unrelenting. Yet its leaders often disagreed on the best method to rid the nation of slavery. Garrison advocated peace and persuasion. Brown, the leader of the raid on Harper’s Ferry, believed it could only be achieved through bloodshed.

Setbacks including the passage of the Fugitive Slave Law and the Supreme Court’s decision in the Dred Scott Case that Congress could not outlaw slavery radicalized even Garrison. He came to believe the entire nation needed to start over, that the first republic, as it was known, had to die to create that “more perfect union” as cited in the preamble to the U.S. Constitution.

Rapley’s film does a decent job of slicing through the mythology of the abolitionist movement to show how much its leaders both worked together and disagreed while still keeping a collective eye on the prize. It also disabuses us of the notion that Lincoln was the great white hope of the abolitionist movement from the get-go. That isn’t to say he shouldn’t be viewed as a hero, only that, like much of the nation, his views on slavery had to evolve.

Rapley’s film is watchable and informative, but the re-enactments come up short. He’s employed experienced actors to play Garrison, Brown and the others, but because scenes rarely feel very believable, they don’t contribute as much as the archival photographs and other historical images. Of the actors, only Richard Brooks ( Law & Order, Firefly) as Douglass manages to overcome the phoniness of the settings.

The film also includes a good deal of commentary from modern-day historians, but their contributions often seem merely to repeat the information provided in Oliver Platt’s narration. What’s largely missing from the commentary, especially given the fact that it’s a three-hour documentary, is how the abolitionist movement may have impacted our nation beyond the Civil War. Slavery may have been eradicated, but the debate about race continues, and its roots can be found in the abolitionist movement.