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Events on Friday 20 July 1866 2
1826 – 1866Bernhard Riemann (1826-1866)Died 20 July 1866, aged 39German mathematician whose work on geometry and complex analysis laid the mathematical foundations later used in Einstein's general relativity. He died of tuberculosis in Italy, and the Riemann hypothesis he posed remains one of mathematics' most famous unsolved problems.
1866Battle of LissaAustrian navy defeats Italy in the AdriaticOff the island of Vis, an outnumbered Austrian fleet under Wilhelm von Tegetthoff routed the Italian navy, notably by ramming and sinking the ironclad Re d'Italia. It was the first major naval battle between ironclad fleets and shaped naval tactics for decades.