February 18 » Second Boer War: Imperial forces suffer their worst single-day loss of life on Bloody Sunday, the first day of the Battle of Paardeberg.
March 7 » The German liner SSKaiser Wilhelm der Grosse becomes the first ship to send wireless signals to shore.
May 18 » The United Kingdom proclaims a protectorate over Tonga.
July 9 » The Federation of Australia is given royal assent.
September 13 » Filipino insurgents defeat a small American column in the Battle of Pulang Lupa, during the Philippine–American War.
December 14 » Quantum mechanics: Max Planck presents a theoretical derivation of his black-body radiation law.
Day of marriage May 21, 1921
The temperature on May 21, 1921 was between 2.0 °C and 19.1 °C and averaged 12.6 °C. There was 12.7 hours of sunshine (80%). The average windspeed was 3 Bft (moderate breeze) and was prevailing from the north-northeast. 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 1 » Following mass protests in Petrograd demanding greater freedom in the RSFSR, the Kronstadt rebellion began, with sailors and citizens taking up arms against the Bolsheviks.
March 17 » The Second Polish Republic adopts the March Constitution.
May 8 » The creation of the Communist Party of Romania.
July 27 » Researchers at the University of Toronto, led by biochemist Frederick Banting, prove that the hormone insulin regulates blood sugar.
September 5 » Roscoe "Fatty" Arbuckle party in San Francisco ends with the death of the young actress Virginia Rappe: One of the first scandals of the Hollywood community.
October 19 » The Portuguese Prime Minister and several officials are murdered in the Bloody Night coup.
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/I212360.php : accessed October 23, 2026), "Derktje Ronda (1900-)".
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