Wikipedia:Selected anniversaries/April 20
April 20: Palm Sunday in Eastern Christianity (2008); Ridván begins at sunset in the Bahá'í Faith, 4/20 in cannabis culture.
- 1653 – Oliver Cromwell dissolved the Rump Parliament of the Commonwealth of England by force, eventually replacing it with the Barebone's Parliament.
- 1862 – French chemist Louis Pasteur (pictured) and physiologist Claude Bernard completed the first test on pasteurization.
- 1884 – Pope Leo XIII published the encyclical Humanum Genus, denouncing Freemasonry, the doctrine of a separation of church and state, and many other principles, some of which are today equated by most people with the founding ones of the United States.
- 1968 – British Member of Parliament Enoch Powell made his controversial "Rivers of Blood" speech in opposition to immigration and anti-discrimination legislation, resulting in his removal from the Shadow Cabinet.
- 1978 – Soviet fighters shot down Korean Air Lines Flight 902 after it violated Soviet airspace and failed to respond to Soviet interceptors.