July 20

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  1597: Scholar, printer, and bookseller Franciscus Raphelengius dies. Raphelengius produced an Arabic-Latin dictionary, about 550 pages, which was published posthumously in 1613 at Leiden — the first publication by printing press of a book-length dictionary for the Arabic language in Latin.

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  1866: Mathematician and academic Bernhard Riemann dies. He made contributions to analysis, number theory, and differential geometry.

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  1932: In Washington, D.C., police fire tear gas on World War I veterans, part of the Bonus Expeditionary Force, who attempt to march to the White House.

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  1937: Businessman and inventor Guglielmo Marconi dies. He shared the 1909 Nobel Prize in Physics with Karl Ferdinand Braun "in recognition of their contributions to the development of wireless telegraphy".

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  1945: The United States Secretary of State approves the transfer of Wernher von Braun and his team of Nazi rocket scientists to the U.S. under Operation Paperclip.

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  1977: Project MKUltra (nonfiction): The Central Intelligence Agency releases documents under the Freedom of Information Act revealing it had engaged in mind-control experiments.

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  2018: Pin Man says he "was an unwilling test subject in the Project MKUltra (nonfiction)."