- January 1 - Legislative union of Great Britain and Ireland completed
- January 1 - The first (and largest) asteroid Ceres is discovered by Giuseppe Piazzi
- April 2 - First Battle of Copenhagen. Armed Neutrality of the North dissolved.
- May - The pascha of Tripoli declares war on United States of America by having the flagpole on the consulate chopped down.
- Joseph-Marie Jacquard developed a loom where the pattern being woven was controlled by punch cards.
- Thomas Jefferson succeeds John Adams as the President of the United States of America