1780 was a leap year.
|Centuries:||17th century – 18th century – 19th century|
|Decades:||1750s 1760s 1770s – 1780s – 1790s 1800s 1810s|
|Years:||1777 1778 1779 – 1780 – 1781 1782 1783|
- January 16 – American Revolutionary War: Battle of Cape St. Vincent
- February – Armed Neutrality of the North alliance formed between Denmark, Sweden, and Russia.
- March 26 – The British Gazette and Sunday Monitor, the first Sunday newspaper in Britain
- April 16 – The University of Münster in Münster, North Rhine-Westphalia, Germany is founded
- May 12 – American Revolutionary War: Charleston, South Carolina is taken by British forces.
- May 29 – American Revolutionary War: Loyalist forces under Col. Banastre Tarleton kill surrendering American soldiers in the Waxhaw Massacre.
- August 16 – American Revolutionary War: Battle of Camden – The British defeat the Americans near Camden, South Carolina.
- September 25 – Benedict Arnold flees to British-held New York
- October 2 – American Revolutionary War: British spy John Andre is hanged by American forces.
- October 10-16 – Great hurricane flattens the islands of Barbados, Martinique and St. Eustatius
- November 29 – Maria Theresa of Austria dies and her Habsburg dominions pass to her ambitious son, Joseph II, who has already been Holy Roman Emperor since 1765.
- Britain attacks the United Provinces before it can join the Neutral Alliance, because of its support for the American uprising.
- First Epsom Derby horse race run at Epsom Downs, Surrey, England.
- Emperor Kokaku ascends to the throne of Japan
- In Ireland, Lady Berry, who is sentenced to death for the murder of her son, is released when she agrees to become an executioner (retires 1810)
- Good grain and wine harvest in France
- 35th and last volume of Diderot's Encyclopédie published
- for more information, see Category:1780 births.
- for more information, see Category:1780 deaths.