The Hankey carried British colonists in the late eighteenth century to the coast of Africa, where they intended to found a settlement that would prove antislavery principles by hiring African laborers rather than enslaving them, though they didn’t think of the land as already settled. That project didn’t go well, but it was on its return that the ship’s largest impact occurred, when it carried yellow fever wherever it went, including the French Carribean—assisting in Haiti’s rebellion—and Philadelphia—confirming Jefferson’s distrust of cities. A very sad story of imperial arrogance and individual persistence in misguided endeavors. Also, I appreciated the reminder that science has always been political: Hamilton resisted Benjamin Rush’s bleeding cure because it was “democratic,” which turned out to be lucky for Hamilton. ( )

"The surviving British numbered only thirteen, nine of whom couldn't get out of bed. The end seemed imminent",, 26 August 2015

This review is from: Ship of Death: A Voyage That Changed the Atlantic World (Kindle Edition)
Read during a global reading challenge (one of the few books set in Guinea Bissau I could find). this is a very readable and interesting historical work that reads in part like an adventure story.
This is the account of the 1792 voyage by a group of mainly English people with the aim of founding a colony on Bolama, an island off the Bissau coast. Their motives were various, but were led by a desire to help end slavery - by proving that Africans could be used as paid labour with no need for enslavement. And if that sounds rather naive, the whole endeavour is soon shown to be dogged with disaster: violent tribes, endless rain, disputes...and disease.
But the most important result of their attempt was their ultimate carrying of a particularly virulent strain of yellow fever to the Caribbean, and thence to America and Europe. The independence of Haiti, Billy Smith argues, came about thanks to the 'Hankey' and its fatal infection of the European soldiers who were attempting to suppress the (largely immune) Africans. And Napoleon's decision to sell his US territory was a follow-on from his loss of Haiti - with a massive impact on American power.
As the author concludes: "Seemingly insignificant events, like the beating of the wings of a butterfly (or a mosquito) can have enormous consequences half a globe away.." ( )