September 13

Overview and calendar facts

The numbering of this date makes it notable for computing and cultural observances: the 256th day of a year is celebrated by some as Programmers' Day, which falls on September 13 in common years and on September 12 in leap years. Because the date occupies the same ordinal position in the calendar cycle described above, the count of remaining days (109) is unchanged between leap and common years.

Historical events and anniversaries

Several widely remembered events fall on September 13. In 1759 the Battle of the Plains of Abraham near Quebec City resulted in a decisive British victory during the Seven Years' War. On September 13–14, 1814, the British bombardment of Fort McHenry inspired Francis Scott Key to compose the poem that later became the United States national anthem. More recently, on September 13, 1993, leaders of Israel and the Palestine Liberation Organization signed a landmark agreement in Washington, D.C.

Observances and public awareness

The date is used for international and national awareness days. World Sepsis Day is observed on September 13 to raise global awareness about sepsis prevention, diagnosis and treatment. Other commemorations, local holidays and religious feast days may also occur on this date in various calendars and communities.

Uses, examples and cultural notes

Because September 13 sits near the transition between seasons in many countries, it often appears in literary, cultural and agricultural calendars as a moment for harvest-related activity or back-to-school timing in the Northern Hemisphere. The day is also a convenient landmark in annual reporting, planning and historical timelines because its ordinal position is simple to calculate.

Notable births and distinctions

• Author Roald Dahl, known for children's books including Charlie and the Chocolate Factory, was born on September 13, 1916.
• The date has recurring significance in military, diplomatic and medical histories due to the variety of unrelated but consequential events that share it.

As with any calendar date, September 13 collects a wide variety of local observances and historical markers; specific commemorations vary by country, culture and religious tradition.