Rough Crossings dramatizes a little-known, horrifying chapter in the history of African American slaves and their quest for freedom after the American Revolution.

“There are some stories so big,” says Simon Schama at the start of his latest documentary, “stories that tell us who we are and what we’ve become, that you can’t believe they ever got away!” The Columbia University history professor and award-winning author tells just such a story in Rough Crossings, a 90-minute film set to air on Sunday, February 19 at 3 p.m. witf. This little-known chapter of history begins after the American Revolution, in which thousands of African American slaves risked everything to fight for the British in exchange for a promise of freedom.

Using journals, diaries, autobiographical accounts, and dramatizations, Schama (The Power of Art) reconstructs the story of John Clarkson, a young British Navy lieutenant sent by British abolitionists to North America to transport and settle former slaves in a colony of free commerce and self-government. When frigid, rocky Nova Scotia proved to be inhospitable to those who had been working the cotton fields of the Deep South, Clarkson arranged to transport them again – this time on a harrowing journey across the Atlantic, to sweltering Sierra Leone, where each passenger would be entitled to a piece of free African land.

But when the fleet arrived at the “Province of Freedom,” Schama says, their dreams of a free haven were quickly shattered. No shelters awaited them. Not even a single tree felled. The Sierra Leone Company in London had deceived Clarkson and the settlers, making it clear that the blacks were expected to work the land themselves – and obey the whites’ rules. Disease and storms, power struggles and rebellion jeopardized the survival of the colony.

But as Schama points out, “History isn’t Hollywood…this great experiment in black democracy did fall apart, but the idea of Freetown endured. After Britain abolished slavery in 1833, Sierra Leone became the country to which those liberated from the slave forts and ships and plantation flocked for a new life as free Africa.”