Wikipedia:Selected anniversaries/April 21
This is a list of selected April 21 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, featured list 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 21: Administrative Professionals' Day (2010); Grounation Day in the Rastafari movement; First day of Ridván in the Bahá'í Faith; Tiradentes Day in Brazil
- 900 – A debt is pardoned by the Datu of Tondo on the island of Luzon, as inscribed on the Laguna Copperplate Inscription, the earliest known written document found in the Philippines.
- 1509 – Henry VIII (pictured) became King of England, following the death of his father Henry VII, eventually becoming a significant figure in the history of the English monarchy.
- 1918 – The German fighter pilot known as "The Red Baron", the most successful flying ace of World War I with 80 confirmed air combat victories, was shot down and killed near Vaux-sur-Somme in France.
- 1960 – Brasília, a planned city primarily designed by architect and urban planner Lúcio Costa, was officially inaugurated, replacing Rio de Janeiro as the capital of Brazil.
- 1970 – In response to a long-running dispute over wheat production quotas, the Principality of Hutt River proclaimed their secession from Western Australia.