| 115411 | October 9 | Event | 1635 – Founder of Rhode Island Roger Williams is banished from the Massachusetts Bay Colony as a religious dissident after he speaks out against punishments for religious offenses and giving away Native American land. |
| 115412 | October 9 | Event | 1701 – The Collegiate School of Connecticut (later renamed Yale University) is chartered in Old Saybrook, Connecticut. |
| 115413 | October 9 | Event | 1708 – Peter the Great defeats the Swedes at the Battle of Lesnaya. |
| 115414 | October 9 | Event | 1740 – Dutch colonists and various slave groups begin massacring ethnic Chinese in Batavia, eventually killing 10,000 and leading to a two-year-long war throughout Java. |
| 115415 | October 9 | Event | 1760 – Seven Years' War: Russian forces occupy Berlin. |
| 115416 | October 9 | Event | 1771 – The Dutch merchant ship Vrouw Maria sinks near the coast of Finland. |
| 115417 | October 9 | Event | 1799 – Sinking of HMS Lutine with the loss of 240 men and a cargo worth £1,200,000. |
| 115418 | October 9 | Event | 1804 – Hobart, capital of Tasmania, is founded. |
| 115419 | October 9 | Event | 1806 – Prussia begins the War of the Fourth Coalition against France. |
| 115420 | October 9 | Event | 1812 – War of 1812: In a naval engagement on Lake Erie, American forces capture two British ships: HMS Detroit and HMS Caledonia. |
| 115421 | October 9 | Event | 1820 – Guayaquil declares independence from Spain. |
| 115422 | October 9 | Event | 1824 – Slavery is abolished in Costa Rica. |
| 115423 | October 9 | Event | 1831 – Ioannis Kapodistrias, the first head of state of independent Greece is assassinated. |
| 115424 | October 9 | Event | 1834 – Opening of the Dublin and Kingstown Railway, the first public railway on the island of Ireland. |
| 115425 | October 9 | Event | 1845 – The eminent and controversial Anglican, John Henry Newman, is received into the Roman Catholic Church. |
| 115426 | October 9 | Event | 1854 – Crimean War: The siege of Sebastopol begins. |
| 115427 | October 9 | Event | 1861 – American Civil War: Battle of Santa Rosa Island: Union troops repel a Confederate attempt to capture Fort Pickens. |
| 115428 | October 9 | Event | 1864 – American Civil War: Battle of Tom's Brook: Union cavalrymen in the Shenandoah Valley defeat Confederate forces at Toms Brook, Virginia. |
| 115429 | October 9 | Event | 1873 – A meeting at the U.S. Naval Academy establishes the U.S. Naval Institute. |
| 115430 | October 9 | Event | 1874 – General Postal Union is created as a result of the Treaty of Bern. |
| 115431 | October 9 | Event | 1888 – The Washington Monument officially opens to the general public. |
| 115432 | October 9 | Event | 1900 – The Cook Islands become a territory of the United Kingdom. |
| 115433 | October 9 | Event | 1907 – Las Cruces, New Mexico is incorporated. |
| 115434 | October 9 | Event | 1911 – An accidental bomb explosion in Hankou, Wuhan, China leads to the ultimate fall of the Qing Empire |
| 115435 | October 9 | Event | 1913 – The steamship SS Volturno catches fire in the mid-Atlantic. |
| 115436 | October 9 | Event | 1914 – World War I: Siege of Antwerp: Antwerp, Belgium falls to German troops. |
| 115437 | October 9 | Event | 1919 – Black Sox Scandal: The Cincinnati Reds win the World Series. |
| 115438 | October 9 | Event | 1934 – Regicide at Marseille: The assassination of King Alexander I of Yugoslavia and Louis Barthou, Foreign Minister of France. |
| 115439 | October 9 | Event | 1936 – Generators at Boulder Dam (later renamed to Hoover Dam) begin to generate electricity from the Colorado River and transmit it 266 miles to Los Angeles. |
| 115440 | October 9 | Event | 1940 – World War II: Battle of Britain: During a night-time air raid by the German Luftwaffe, St. Paul's Cathedral in the City of London, England is hit by a bomb. |