January 18 » An X-ray generating machine is exhibited for the first time by H. L. Smith.
February 1 » La bohème premieres in Turin at the Teatro Regio (Turin), conducted by the young Arturo Toscanini.
April 15 » Closing ceremony of the Games of the I Olympiad in Athens, Greece.
September 22 » Queen Victoria surpasses her grandfather King George III as the longest reigning monarch in British history.
November 17 » The Western Pennsylvania Hockey League, which later became the first ice hockey league to openly trade and hire players, began play at Pittsburgh's Schenley Park Casino.
December 30 » Canadian ice hockey player Ernie McLea scores the first hat-trick in Stanley Cup play, and the Cup-winning goal as the Montreal Victorias defeat the Winnipeg Victorias 6–5.
Day of marriage May 10, 1921
The temperature on May 10, 1921 was between 6.2 °C and 17.3 °C and averaged 11.9 °C. There was 1.0 mm of rain. There was 6.4 hours of sunshine (42%). The average windspeed was 2 Bft (weak wind) and was prevailing from the south. Source: KNMI
In The Netherlands , there was from September 9, 1918 to September 18, 1922 the cabinet Ruys de Beerenbrouck I, with Jonkheer mr. Ch.J.M. Ruys de Beerenbrouck (RKSP) as prime minister.
February 21 » Rezā Shāh takes control of Tehran during a successful coup.
March 20 » The Upper Silesia plebiscite was a plebiscite mandated by the Versailles Treaty to determine a section of the border between Weimar Germany and Poland.
May 31 » The Tulsa race massacre kills at least 39, but other estimates of black fatalities vary from 55 to about 300.
June 20 » Workers of Buckingham and Carnatic Mills in the city of Chennai, India, begin a four-month strike.
October 18 » The Crimean Autonomous Soviet Socialist Republic is formed as part of the Russian Soviet Federative Socialist Republic.
November 4 » Japanese Prime Minister Hara Takashi is assassinated in Tokyo.
When copying data from this family tree, please include a reference to the origin: J. Ham, "Family tree Ham", database, Genealogy Online (https://www.genealogieonline.nl/stamboom-ham/I71844.php : accessed March 13, 2026), "Johannes Jacobus Marinus Grotens (1896-????)".
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