January 31 » Czechoslav Trade Union Association is founded in Prague.
April 18 » The Greco-Turkish War is declared between Greece and the Ottoman Empire.
April 30 » J. J. Thomson of the Cavendish Laboratory announces his discovery of the electron as a subatomic particle, over 1,800 times smaller than a proton (in the atomic nucleus), at a lecture at the Royal Institution in London.
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.
August 31 » Thomas Edison patents the Kinetoscope, the first movie projector.
September 11 » After months of pursuit, generals of Menelik II of Ethiopia capture Gaki Sherocho, the last king of Kaffa, bringing an end to that ancient kingdom.
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.
January 20 » The British K-class submarine HMS K5 sinks in the English Channel; all 56 on board die.
February 22 » After Russian forces under Baron Roman von Ungern-Sternberg drive the Chinese out, the Bogd Khan is reinstalled as the emperor of Mongolia.
May 8 » The creation of the Communist Party of Romania.
September 11 » Nahalal, the first moshav in Palestine, is settled as part of a Zionist plan of creating a Jewish state, later to be Israel.
October 29 » United States: Second trial of Sacco and Vanzetti in Boston, Massachusetts.
November 14 » The Communist Party of Spain is founded, and issues the first edition of Mundo obrero.
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.
February 24 » The United States Olympic hockey team completes its Miracle on Ice by defeating Finland 4–2 to win the gold medal.
July 29 » Iran adopts a new "holy" flag after the Islamic Revolution.
July 30 » Vanuatu gains independence.
August 27 » A massive bomb planted by extortionist John Birges explodes at Harvey's Resort Hotel in Stateline, Nevada after a failed disarming attempt by the FBI. Although the hotel is damaged, no one is injured.
September 18 » Soyuz 38 carries two cosmonauts (including one Cuban) to the Salyut 6 space station.
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 29, 2026), "Roelof Jacobus Coertze (1897-1980)".
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