In early 1858, when he was in the Moluccas, Wallace drafted an essay to explain evolution by natural selection and posted it to Darwin. For many years it was believed that the Ternate essay left the island in March on the monthly mail steamer, and arrived at Down House on 18 June 1858. Darwin immediately wrote to Lyell, as requested by Wallace, forwarding the essay. This sequence was cast in doubt after the discovery of a letter written by Wallace to Bates leaving on the same steamer with postmarks showing its arrival in Leicester on 3 June 1858. Darwin has been accused of keeping the essay secret for a fortnight, thereby enabling him to revise elements of his theory of evolution. We intend to show that Wallace in fact sent the Ternate essay on the mail steamer of April 1858, for which the postal connections actually indicate the letter to have arrived precisely on 18 June. Darwin is thus vindicated from accusations of deceit. Wallace's Ternate essay and extracts from Darwin's theoretical manuscripts were read at a meeting of the Linnean Society of London on 1 July 1858, which is now recognized as a milestone in the history of science. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 249–252.