Historical Events on May 21

20 significant historical events occurred on May 21. May 21 has been a day of landmark historical events across decades, with eight notable occurrences. On this date, important events include the Battle of Arras during World War II in 1940, the devastating 1960 Valdivia earthquake in Chile with a magnitude of 9.4–9.6, and the 1991 assassination of Indian Prime Minister Rajiv Gandhi. Additionally, there was the dangerous demon core plutonium incident in 1946 and the 1950 Monaco Grand Prix Formula One race.