January 16 » The United States Senate accepts the Anglo-German treaty of 1899 in which the United Kingdom renounces its claims to the Samoan islands.
March 18 » AFC Ajax Amsterdam, The Netherlands's biggest and most successful football club, was founded.
May 18 » The United Kingdom proclaims a protectorate over Tonga.
July 29 » In Italy, King Umberto I of Italy is assassinated by the anarchist Gaetano Bresci.
September 17 » Philippine–American War: Filipinos under Juan Cailles defeat Americans under Colonel Benjamin F. Cheatham Jr. at Mabitac.
October 19 » Max Planck discovers Planck's law of black-body radiation.
Day of marriage June 13, 1921
The temperature on June 13, 1921 was between 10.3 °C and 16.2 °C and averaged 12.9 °C. There was 1.7 mm of rain. There was 0.7 hours of sunshine (4%). The average windspeed was 4 Bft (moderate breeze) and was prevailing from the west-northwest. 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.
March 18 » The second Peace of Riga is signed between Poland and the Soviet Union.
July 11 » Former president of the United States William Howard Taft is sworn in as 10th chief justice of the U.S. Supreme Court, becoming the only person ever to hold both offices.
July 27 » Researchers at the University of Toronto, led by biochemist Frederick Banting, prove that the hormone insulin regulates blood sugar.
October 29 » United States: Second trial of Sacco and Vanzetti in Boston, Massachusetts.
November 4 » Japanese Prime Minister Hara Takashi is assassinated in Tokyo.
December 6 » The Anglo-Irish Treaty is signed in London by British and Irish representatives.
When copying data from this family tree, please include a reference to the origin: Hans Weening, "Family tree Weening", database, Genealogy Online (https://www.genealogieonline.nl/stamboom-weening/I131786.php : accessed October 22, 2026), "Siebe Nijboer (1900-)".
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