April 21
day of the year
April 21 is the 111th day of the year (112th in leap years) in the Gregorian calendar; 254 days remain until the end of the year.
Events
Pre-1600
753 BC – Romulus founds Rome (traditional date).
43 BC – Battle of Mutina: Mark Antony is again defeated in battle by Aulus Hirtius, who is killed. Antony fails to capture Mutina and Decimus Brutus is murdered shortly after.
900 – The Laguna Copperplate Inscription (the earliest known written document found in what is now the Philippines): the Commander-in-Chief of the Kingdom of Tondo, as represented by the Honourable Jayadewa, Lord Minister of Pailah, pardons from all debt the Honourable Namwaran and his relations.
1092 – The Diocese of Pisa is elevated to the rank of metropolitan archdiocese by Pope Urban II.
1506 – The three-day Lisbon Massacre comes to an end with the slaughter of over 1,900 suspected Jews by Portuguese Catholics.
1509 – Henry VIII ascends the throne of England on the death of his father, Henry VII.
1526 – The last ruler of the Lodi dynasty, Ibrahim Lodi, is defeated and killed by Babur in the First Battle of Panipat.
1601–1900
1615 – The Wignacourt Aqueduct is inaugurated in Malta.
1782 – The city of Rattanakosin, now known internationally as Bangkok, is founded on the eastern bank of the Chao Phraya River by King Buddha Yodfa Chulaloke.
1789 – John Adams sworn in as first US Vice President (nine days before George Washington).
The public source identifies “April 21” as day of the year. This brief keeps that definition visible, then builds a research path around April and year.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Sep 12, 2026. The linked authority identifier is Q2525. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1600, 1092, 1506 and 1509.
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This entry incorporates text from “April 21” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.