At the height of the conflict, Britain guaranteed freedom to any slave who fought for the king against George Washington’s slave-owning rebels. And in 1772, in London, Lord Mansfield, nudged by the advocacy of Granville Sharp, an abolitionist, judged that Africans could not be transported against their will. It sounded good. Thousands of slaves, lacking a better offer, joined the king’s cause.

It goes without saying that Britain’s pledge was issued with only token expectation that it would need to be honoured?victory would surely render it irrelevant. But military incompetence and American resolve turned it into a disquieting political reality. After much smudging, a liberal haven?an 18th-century African Zion?was marked out in Sierra Leone. African-Americans began to go ?home?.

It was a disastrous enterprise from the start; what began as a rescue mission was later seen as a ?racist deportation?. As revolutionary echoes from France made London’s potentates tremble, cargoes of ex-slaves were dumped on a malarial strip of impossible land. Some were seized as slaves again; others, in an even more horrid reverse, became slavers themselves. It was the only business they knew. —Slavery in America: Black and white — and red all over (The Economist)

A review of Simon Schama’s Rough Crossings.