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.
Staging area
Images
Use only ONE image at a time
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Sam Houston -
Sam Houston -
Cathedral of Brasilia -
Nguyễn Văn Thiệu (requires undeletion)
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Maharlika (ruling class) of the Kingdom of Tondo -
Washington's reception at Trenton depicted by N. C. Wyeth -
Manfred von Richthofen -
Mausoleum of four Shia Imams -
Henry VIII of England -
Romulus and Remus suckling from the Capitoline Wolf
Ineligible
| Blurb | Reason |
|---|---|
| Patriots' Day in various U.S. states (1775) | Place holder for 2025 (3rd Monday) |
| Tiradentes Day in Brazil | multiple issues |
| Rama Navami - Hinduism | Hindu calendar |
| 1782 – A city pillar was erected on Rattanakosin Island, located on the eastern bank of the Chao Phraya River, an act considered the founding of the city of Bangkok. | refimprove section |
| 1894 – Norway formally adopted the Krag–Jørgensen, a repeating bolt action rifle designed by the Norwegians Ole Herman Johannes Krag and Erik Jørgensen, as the main firearm of its armed forces. | needs more footnotes, unreferenced section |
| 1918 – Manfred von Richthofen, known as the "Red Baron", was shot down and killed near Vaux-sur-Somme in France, after a career as the most successful fighter pilot of First World War with 80 confirmed air combat victories. | refimprove section |
| 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. | unreferenced section |
| 1967 – Colonel Georgios Papadopoulos overthrew the government of Greek Prime Minister Panagiotis Kanellopoulos, establishing the Regime of the Colonels. | refimprove sections |
| 1967 – The Socialist mayor of Marseille Gaston Defferre and Gaullist legislator René Ribière took up swords in the last duel fought in France. | Defferre: unreferenced section; Ribière: stub |
| 2002 – In the first round of the French presidential election, Jean-Marie Le Pen progressed to the runoff, a result so surprising that "21st of April" is now a common expression in France. | Election: refimprove section, fact not in article; Le Pen: lots of CN tags (8) |
| * 1863 – Following his exile from Baghdad, Baháʼu'lláh, the founder of the Baháʼí Faith, began a twelve-day stay in the Garden of Ridván, where he declared himself to be "He whom God shall make manifest". | article says 22 April |
| * 1914 – Mexican Revolution: The United States detained a German steamer carrying materiel for the Mexican federal government. | One section almost uncited |
| Grounation Day (Rastafari | Citation needed for date in article |
Eligible
- 753 BC – Romulus and Remus (depicted) legendarily founded the city of Rome, according to the calculations of ancient Roman scholar Varro Reatinus.
- 43 BC – Forces led by Mark Antony fought the Battle of Mutina against those of Decimus Brutus, one of Julius Caesar's assassins.
- 995 - Ælfric of Abingdon was appointed Archbishop of Canterbury
- 1509 – Henry VIII became King of England, following the death of his father Henry VII, eventually becoming a significant figure in the history of the English monarchy.
- 1789 – The Ladies of Trenton social club hosted a reception (depicted) for President-elect George Washington as he journeyed to New York City for his first inauguration.
- 1925 or 1926 – Al-Baqi Cemetery in Medina, the site of the mausoleum of four of the Twelve Imams of Shia Islam, was demolished by Wahhabis.
- 1934 – The "Surgeon's Photograph", purportedly showing the Loch Ness Monster (later revealed to be a hoax), was published in the Daily Mail.
- 1958 – United Airlines Flight 736 collided with a U.S. Air Force fighter jet over southern Nevada, resulting in the deaths of all 49 people on board both aircraft.
- 1962 – The Century 21 Exposition, the first world's fair in the United States since World War II, opened in Seattle.
- 1970 – In response to a dispute over wheat production quotas, Leonard Casley declared his 75 km2 (29 sq mi) farm in Western Australia to be an independent country as the Hutt River Province.
- 2010 – Ukraine and Russia signed the Kharkiv Pact, extending the Russian lease on naval facilities in Crimea.
- 2014 – The city of Flint, Michigan, U.S., changed its water source to the Flint River, which exposed residents to lead poisoning.
- Born/died: | Bardas|d|866| Bajkam|d|941| Anselm of Canterbury|d|1109| Petrus Apianus|d|1552| Simon de la Loubère|b|1642| Jan Boeckhorst|d|1668| Max Weber|b|1864| Ignatius Zakka I Iwas|b|1931| Carsten Borchgrevink |d|1934| John Maynard Keynes|d|1946| Mike Wingfield|b|1954| Dorothy Eady|d|1981| Vivian Maier|d|2009
Wignacourt Aqueduct
- 900 – A debt was pardoned by the chief of Tondo on the island of Luzon and recorded on the Laguna Copperplate Inscription, the earliest known calendar-dated document found in the Philippines.
- 1615 – The Wignacourt Aqueduct (pictured) in Malta was inaugurated and was used to carry water to Valletta for about 300 years.
- 1836 – Forces of the Republic of Texas led by Sam Houston defeated the Mexican troops of General Antonio López de Santa Anna in the Battle of San Jacinto, the decisive and final battle of the Texas Revolution.
- 1975 – South Vietnamese president Nguyễn Văn Thiệu resigned on hearing of the fall of Xuân Lộc, the last battle of the Vietnam War.
- 2021 – The Indonesian Navy submarine Nanggala sank, resulting in the deaths of all 53 people on board.
- Pope Alexander II (d. 1073)
- Antonín Kammel (b. 1730)
- Cheryl Gillan (b. 1952)