What happened on September 23

43 documented historical events happened on September 23, from antiquity to the present day. The best known is this: Pope Callixtus II and Holy Roman emperor Henry V agreed the Concordat of Worms (pictured), ending the Investiture Controversy. On the same day, in another year: The Battle of Arnemuiden, in which a French force defeats the English, is the first naval battle of the Hundred Years' War. On Almanaccolo every event is listed in chronological order, grouped by century, and links to the Wikipedia article it comes from, so you can always read further or check the source. Alongside the events you find who was born and who died on this date, and which observances are celebrated around the world.

160 people with a Wikipedia article were born on September 23, including Hilly Kristal, Lloyd J. Old, Prem Chopra. The list spans every era and every field — art, science, politics, sport, entertainment — ordered by year of birth, from the earliest to the most recent. The six featured people are those most has been written about: the ordering uses the length of their Wikipedia article as an indicator of prominence. For each one you find their occupation, year of birth and a link to the full biography.

97 people with a Wikipedia article died on September 23, including Ælfwald I of Northumbria, Al-Mutanabbi, Robert IV of Sablé. The list is in chronological order by year of death and spans all of documented history, from antiquity to the present day. For each person you find their occupation, the year and a link to the Wikipedia biography, where the full story and its sources can be read.

17 observances are celebrated on September 23 around the world: Christian feast day: Adomnán, Christian feast day: Cissa of Crowland (or of Northumbria), Christian feast day: Blessed Francisco de Paula Victor, Christian feast day: Padre Pio, Christian feast day: Pope Linus, Christian feast day: Sossius. The list gathers national holidays, international days and religious or civil observances falling on this date in different countries, as recorded on Wikipedia. Some are fixed and recur on the same day every year; others depend on the local calendar. Each links to the article explaining its origin and meaning.