January 31 » Czechoslav Trade Union Association is founded in Prague.
February 28 » Queen Ranavalona III, the last monarch of Madagascar, is deposed by a French military force.
April 18 » The Greco-Turkish War is declared between Greece and the Ottoman Empire.
June 16 » A treaty annexing the Republic of Hawaii to the United States is signed; the Republic would not be dissolved until a year later.
July 2 » British-Italian engineer Guglielmo Marconi obtains a patent for radio in London.
December 30 » The British Colony of Natal annexes Zululand.
Day of marriage April 30, 1921
The temperature on April 30, 1921 was between 6.8 °C and 20.2 °C and averaged 13.7 °C. There was 12.0 hours of sunshine (81%). The average windspeed was 3 Bft (moderate breeze) and was prevailing from the 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 6 » Portuguese Communist Party is founded as the Portuguese Section of the Communist International.
March 24 » The 1921 Women's Olympiad begins in Monte Carlo, first international women's sports event.
May 3 » West Virginia becomes the first state to legislate a broad sales tax, but does not implement it until a number of years later due to enforcement issues.
July 11 » A truce in the Irish War of Independence comes into effect.
July 27 » Researchers at the University of Toronto, led by biochemist Frederick Banting, prove that the hormone insulin regulates blood sugar.
September 21 » A storage silo in Oppau, Germany, explodes, killing 500–600 people.
Day of death September 2, 1980
The temperature on September 2, 1980 was between 7.3 °C and 20.5 °C and averaged 14.1 °C. There was -0.1 mm of rain. There was 10.5 hours of sunshine (77%). The partly clouded was. The average windspeed was 1 Bft (weak wind) and was prevailing from the south-southeast. Source: KNMI
In The Netherlands , there was from Monday, December 19, 1977 to Friday, September 11, 1981 the cabinet Van Agt I, with Mr. A.A.M. van Agt (CDA/KVP) as prime minister.
March 23 » Archbishop Óscar Romero of El Salvador gives his famous speech appealing to men of the El Salvadoran armed forces to stop killing the Salvadorans.
April 3 » US Congress restores a federal trust relationship with the 501 members of the Shvwits, Kanosh, Koosharem, and the Indian Peaks and Cedar City bands of the Paiute people of Utah.
July 24 » The Quietly Confident Quartet of Australia wins the men's 4 x 100 metre medley relay at the Moscow Olympics, the only time the United States has not won the event at Olympic level.
August 2 » A bomb explodes at the railway station in Bologna, Italy, killing 85 people and wounding more than 200.
August 14 » Lech Wałęsa leads strikes at the Gdańsk, Poland shipyards.
September 1 » Major General Chun Doo-hwan becomes President of South Korea, following the resignation of Choi Kyu-hah.
When copying data from this family tree, please include a reference to the origin: Hendrik Dreyer, "Dreyer Tree", database, Genealogy Online (https://www.genealogieonline.nl/dreyer-tree/I18762.php : accessed January 24, 2026), "Roelof Jacobus Coertze (1897-1980)".
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