In 1804 when W. B. Stevenson (fl. 1803–25) arrived on the small island of Mocha, just off the coast of South America, he stepped onto a continent on the brink of mass revolution. Over the next twenty years, he had an extraordinary range of experiences: as a traveller, a Spanish government official, a prisoner, and as secretary to an ex-Royal Navy admiral turned revolutionary. In this three-vo…