Wikipedia:Selected anniversaries/April 20
This is a list of selected April 20 anniversaries that appear in the "On this day" section of the Main Page. To suggest a new item, in most cases, you can be bold and edit this page. Please read the selected anniversaries guidelines before making your edit. However, if your addition might be controversial or on a day that is or will soon be on the Main Page, please post your suggestion on the talk page instead.
Please note that the events listed on the Main Page are chosen based more on relative article quality and to maintain a mix of topics, not based solely on how important or significant their subjects are. Only four to five events are posted at a time and thus not everything that is "most important and significant" can be listed. In addition, an event is generally not posted this year if it is also the subject of the scheduled featured article or picture of the day.
To report an error when this appears on the Main Page, see Main Page errors. Please remember that this list defers to the supporting articles, so it is best to achieve consensus and make any necessary changes there first.
April 20: Easter Monday (Eastern Christianity, 2009); Patriots' Day (Massachusetts and Maine, 2009); Ridván begins at sunset (Bahá'í Faith); 4/20 (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 as well as a number of beliefs and practices purportedly associated with it such as popular sovereignty and the separation of church and state.
- 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.
- 1999 – Students Eric Harris and Dylan Klebold embarked on a massacre, killing 13 people and wounding over 20 others before committing suicide at Columbine High School in Columbine, Colorado, USA.