June 24 - Matthew Thornton, American signer of the Declaration of Independence (b. 1714)
September 5 - François Devienne, French composer (b. 1759)
September 15 - Gian Francesco Albani, Italian Catholic cardinal (b. 1719)
September 17 - Franz Xaver Süssmayr, Austrian composer (b. 1766)
September 20 - Robert Emmet, Irish patriot (b. 1780)
December 18 - Johann Gottfried Herder, German writer (b. 1744)
December 30 - Francis Lewis, signer of the American Declaration of Independence (b. 1713)
Events
February 14 - Chief Justice John Marshall declares that any act of U.S. Congress that conflicts with the Constitution is void.
February 24 - The Supreme Court of the United States, in Marbury v. Madison, establishes the principle of judicial review.
March 1 - Ohio is admitted as the 17th U.S. state.
March 3 - Colégio Militar is founded in Portugal by Colonel Teixeira Rebello.
April 30 - Louisiana Purchase: The United States purchases the Louisiana Territory from France for $15 million, more than doubling the size of the young nation.
May 18 - Napoleonic Wars: The United Kingdom revokes the Treaty of Amiens and declares war on France.
July 4 - The Louisiana Purchase is announced to the American people.
July 5 - The convention of Artlenburg leads to the French occupation of Hanover (which had been ruled by the British king).
July 26 - The Surrey Iron Railway, arguably the world's first public railway, opens in south London.
August 31 - Lewis and Clark start their expedition to the west by leaving Pittsburgh, Pennsylvania at 11 o clock in the morning.
September 3 - English scientist John Dalton started using symbols to represent the atoms of different elements.
September 23 - Second Anglo-Maratha War: Battle of Assaye.
October 20 - The United States Senate ratifies the Louisiana Purchase.
November 18 - The Battle of Vertières, the last major battle of the Haitian Revolution, is fought, leading to the establishment of the Republic of Haiti, the first black republic in the Western Hemisphere.
November 30 - In New Orleans, Louisiana, Spanish representatives officially transfer Louisiana Territory to a French representative. Just 20 days later, France transfers the same land to the United States as the Louisiana Purchase.
December 20 - The Louisiana Purchase is completed at a ceremony in New Orleans.
