April 9 in history: • 193 – Year of the Five Emperors: Septimius Severus was proclaimed Roman emperor by his troops at Carnuntum in modern-day Austria. → go there • 1388 – Despite being vastly outnumbered, forces of the Old Swiss Confederacy defeated an Austrian army at the Battle of Näfels. → go there • 1860 – Édouard-Léon Scott de Martinville recorded himself singing "Au clair de la lune" on his phonautograph, producing the oldest known recording of an audible human voice (audio featured). → go there • 1976 – The first EMD F40PH, Amtrak's most widespread diesel locomotive for many years, entered into service. → go there • 2021 – Prince Philip, the consort of Queen Elizabeth II, died at Windsor Castle aged 99. → go there Died 1626: Francis Bacon → go there Born 1921: Mary Jackson Wiki link Born 1926: Hugh Hefner Wiki link Born 2001: Nika Mühl Wiki link Pictured: "Au clair de la lune" by Édouard-Léon<br/>Scott de Martinville.