Michaud, a native of Vevey on the shores of Lake Geneva, emigrated to Brazil at the age of nineteen, landing at Rio de Janeiro on 1 February 1849. By 1852 he had settled in the Swiss colony at Superagui, on the Atlantic coast south-west of Sao Paolo, which was then under the control of Swiss Consul-General Charles Perret-Gentil. The life of a coffee planter was clearly very agreeable, and he was soon able to devote himself to studying the peoples, fauna and flora of the Brazilian coast and to the vivid watercolours which he sent home in his lengthy letters to his sisters in Switzerland. Michaud remained in Superagui even during the troubles that followed the abdication of the Emperor in 1889, dying there in 1902 still refusing to return to Europe.
A collection of 73 letters and 76 drawings and watercolours were donated to the Musée Historique de Vevey by one of Michaud's sisters, Nancy Monnerat-Michaud, in 1922, and formed the basis for an exhibition at the museum on the centenary of his death (M. Guisan and F. Lambert, William Michaud (1829-1902), Lettres, dessins et aquarelles d'’un émigrant vaudois au Brésil, exhib. cat., Vevey, Musée Historique, 2002).