Wikipedia:Selected anniversaries/September 14
- 786 - Harun al-Rashid became the Abbasid caliph upon the death of his brother al-Hadi.
- 1752 - The British Empire adopted the Gregorian calendar, skipping eleven days (September 2 was followed directly by September 14 this year).
- 1812 - The Russian army set Moscow on fire to prevent Napoleon from capturing the city.
- 1901 - Theodore Roosevelt became President of the United States.
- 1959 - The Soviet probe Luna 2 crashed onto and became the first man-made object to reach the Moon.
- 1960 - The Organization of the Petroleum Exporting Countries (OPEC) was founded by Iran, Iraq, Kuwait, Venezuela and Saudi Arabia.
Recent days: September 13 – September 12 – September 11