September 21
Overview
Holidays & Observances
Autumnal equinoxobservances in the Northern Hemisphere,vernal equinoxobservances in the Southern Hemisphere (seeSeptember 22):
Spring Day (Argentina)
Spring Day in Argentina marks the arrival of the vernal equinox in the Southern Hemisphere, celebrated with vibrant outdoor festivities and student gatherings. It symbolizes renewal as flowers bloom and temperatures warm across the country.
Christianfeast day:
Ephigenia of Ethiopia, Laurent-Joseph-Marius Imbert(one of theKorean Martyrs), Matthew the Evangelist(Western Church), Nativity of the Theotokos(Eastern Orthodox Church,Julian calendar), September 21 (Eastern Orthodox liturgics)
A collection of Christian observances honor saints and sacred events on September 21 across Western and Eastern traditions.
Arbor Day (Brazil)
Brazilian Arbor Day is dedicated to planting and nurturing trees, highlighting the vital role of forests in ecology and community well-being.
Commemoration of the Declaration of Martial Law(Philippines)
This day in the Philippines marks the 1972 declaration of martial law under President Ferdinand Marcos, a defining moment with enduring political implications.
Customs Service Day(Poland)
Customs Service Day in Poland honors the dedication of customs officers who protect the nation’s borders, economy, and public safety.
Founder's DayandNational Volunteer Day(Ghana)
Ghana’s Founder's Day honors the country’s founding figures, while National Volunteer Day celebrates citizens’ contributions to community development.
Independence Day, celebrates the independence ofArmeniafrom theSoviet Unionin 1991.
Armenia’s Independence Day celebrates its declaration of independence from the Soviet Union in 1991 with patriotic festivities and cultural events.
Independence Day, celebrates the independence ofBelizefrom the United Kingdom in 1981.
Belize’s Independence Day marks its 1981 separation from the United Kingdom and celebrates its cultural diversity with parades and music.
Independence Day, celebrates the independence ofMaltafrom the United Kingdom in 1964.
Malta’s Independence Day commemorates its 1964 liberation from British rule with ceremonial events and cultural celebrations.
Events
Emperor Avitus enters Italy with a Gallic army and consolidates his power.
In 455 AD, Emperor Avitus crossed the Alps with a Gallic force to enter Italy and assert his authority over the Western Roman Empire.
Anglo-Norman invasion of Ireland: The Kingdom of Dublin falls to Anglo-Norman invaders.
On September 21, 1170, Anglo-Norman forces captured the Kingdom of Dublin, marking a crucial step in the Norman conquest of Ireland.
Livonian Crusade: The Estonian leader Lembitu and Livonian leader Caupo of Turaida are killed in the Battle of St. Matthew's Day.
During the Livonian Crusade, the allied pagan leaders Lembitu and Caupo of Turaida died in the Battle of St. Matthew's Day in 1217.
The Treaty of Arras is promulgated, causing Burgundy to switch sides in the Hundred Years' War.
The Treaty of Arras of 1435 realigned alliances in the Hundred Years' War, as Burgundy abandoned England and reconciled with France.
A British government army led by Sir John Cope is defeated in less than 15 minutes by the Jacobite forces of Prince Charles Edward Stuart.
On September 21, 1745, the Jacobite army under Prince Charles Edward Stuart overwhelmed Sir John Cope's forces at the Battle of Prestonpans in under fifteen minutes.
Part of New York City is burned shortly after being occupied by British forces.
After British forces occupied New York City in September 1776, a fire swept through Lower Manhattan, causing widespread destruction.
American Revolutionary War: Benedict Arnold gives the British the plans to West Point.
On September 21, 1780, American General Benedict Arnold met with the British, providing them with detailed plans to capture West Point.
French Revolution: The National Convention abolishes the monarchy.
On September 21, 1792, the French National Convention officially abolished the monarchy, declaring the First French Republic.
British Secretary of War Lord Castlereagh and Foreign Secretary George Canning meet in a duel on Putney Heath, with Castlereagh wounding Canning in the thigh.
On September 21, 1809, British statesmen Lord Castlereagh and George Canning fought a duel on Putney Heath after a heated Cabinet dispute.
Births
Pope Vitalian (c.580–672) served as the head of the Catholic Church from 657 until his death, noted for strengthening ties with imperial authorities and promoting liturgical uniformity.
Abu Ishaq Ibrahim
Abu Ishaq Ibrahim (b.953) was a prince of the Buyid dynasty, a Shi'a Iranian family that held de facto power over parts of Iran and Iraq in the 10th century.
Bertha of Savoy (c.1051–1087) was Empress consort of the Holy Roman Empire as the wife of Henry IV, playing a key role in medieval dynastic politics.
Frederick I
Frederick I (1371–1440) was the first Hohenzollern Elector of Brandenburg, appointed by Emperor Sigismund, and he established the principality’s dynastic foundations.
Leonello d'Este
Leonello d'Este (1407–1450) was the Marquis of Ferrara, celebrated as a Renaissance patron who transformed his court into a center of humanist culture.
Richard of York
Richard of York (1411–1460), 3rd Duke of York, was a leading figure in the Wars of the Roses and twice served as Lord Protector of England.
Frederick III
Frederick III (1415–1493) was Holy Roman Emperor from 1452 to his death, notable for his diplomatic skills and his enigmatic motto A.E.I.O.U.
Jingtai Emperor (Zhu Qiyu; 1428–1457) ruled the Ming dynasty from 1449 to 1457 and is remembered for stabilizing the empire after his brother’s capture.
Guillaume Fichet
Guillaume Fichet (1433–1480) was a French scholar and one of the pioneers of printing in Paris, instrumental in introducing the first press to France.
Deaths
Virgil
Ancient Roman poet of the Augustan era, best known for the epic Aeneid.
Flavius Aetius
Influential Roman general and statesman who halted Attila the Hun at the Battle of the Catalaunian Plains.
Pope of the Catholic Church from 686 to 687, known for his brief papacy.
Otto-William
Count of Burgundy and Nevers in the early 11th century, foundational figure of the Burgundian state.
Lembitu
Leader of Estonian resistance against the Livonian Crusade, revered as a national hero.
Latvian chieftain and one of the first Baltic rulers to convert to Christianity.
King of Hungary from 1205 to 1235, notable for issuing the Golden Bull of 1222.
William of Kilkenny
13th-century English cleric who served as Lord Chancellor under King Henry III.
King of England from 1307 to 1327, deposed by his wife and her ally.