1780 was a leap year starting on Saturday (see link for calendar).

Events

• 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
• 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

Births

• April 29 - Charles Nodier, French author.
• June 1 - Carl von Clausewitz, German strategist
• August 1 - Francis Scott Key, American lawyer and poet, famous as the author of the "Star Spangled Banner"
• December 26 - Mary Fairfax Somerville, UK mathematician
• John Bird Sumner, Archbishop of Canterbury (d. 1862)

Deaths

• September 8 - Enoch Poor, Brigadier General in the Continental Army (b. 1736)
• November 29 - Maria Theresa, archduchess of Austria, Queen of Bohemia and Hungary (see above).

• Thomas Dilworth, British cleric & writer