| 9631 | January 23 | Event | 1879 – Anglo-Zulu War: the Battle of Rorke's Drift ends. |
| 9632 | January 23 | Event | 1897 – Elva Zona Heaster is found dead in Greenbrier County, West Virginia. The resulting murder trial of her husband is perhaps the only case in United States history where the alleged testimony of a ghost helped secure a conviction. |
| 9633 | January 23 | Event | 1899 – The Malolos Constitution is inaugurated, establishing the First Philippine Republic. |
| 9634 | January 23 | Event | 1899 – Emilio Aguinaldo is sworn in as President of the First Philippine Republic. |
| 9635 | January 23 | Event | 1900 – Second Boer War: The Battle of Spion Kop between the forces of the South African Republic and the Orange Free State and British forces ends in a British defeat. |
| 9636 | January 23 | Event | 1904 – Ålesund Fire: the Norwegian coastal town Ålesund is devastated by fire, leaving 10,000 people homeless and one person dead. Kaiser Wilhelm II funds the rebuilding of the town in Jugendstil style. |
| 9637 | January 23 | Event | 1909 – RMS Republic, a passenger ship of the White Star Line, becomes the first ship to use the CQD distress signal after colliding with another ship, the SS Florida, off the Massachusetts coastline, an event that kills six people. The Republic sinks the |
| 9638 | January 23 | Event | 1912 – The International Opium Convention is signed at The Hague. |
| 9639 | January 23 | Event | 1920 – The Netherlands refuses to surrender the exiled Kaiser Wilhelm II of Germany to the Allies. |
| 9640 | January 23 | Event | 1937 – In Moscow, 17 leading Communists go on trial accused of participating in a plot led by Leon Trotsky to overthrow Joseph Stalin's regime and assassinate its leaders. |
| 9641 | January 23 | Event | 1941 – Charles Lindbergh testifies before the U.S. Congress and recommends that the United States negotiate a neutrality pact with Adolf Hitler. |
| 9642 | January 23 | Event | 1942 – World War II: The Battle of Rabaul begins, the first fighting of the New Guinea campaign. |
| 9643 | January 23 | Event | 1943 – World War II: Troops of Montgomery's Eighth Army capture Tripoli in Libya from the German–Italian Panzer Army. |
| 9644 | January 23 | Event | 1943 – World War II: Australian and American forces finally defeat the Japanese army in Papua. |
| 9645 | January 23 | Event | 1943 – Duke Ellington plays at Carnegie Hall in New York City for the first time. |
| 9646 | January 23 | Event | 1943 – World War II: The Battle of Mount Austen, the Galloping Horse, and the Sea Horse on Guadalcanal during the Guadalcanal Campaign ends. |
| 9647 | January 23 | Event | 1945 – World War II: German admiral Karl Dönitz launches Operation Hannibal. |
| 9648 | January 23 | Event | 1950 – The Knesset passes a resolution that states Jerusalem is the capital of Israel. |
| 9649 | January 23 | Event | 1957 – American inventor Walter Frederick Morrison sells the rights to his flying disc to the Wham-O toy company, which later renames it the "Frisbee". |
| 9650 | January 23 | Event | 1958 – After a general uprising and rioting in the streets, President Marcos Pérez Jiménez leaves Venezuela. |
| 9651 | January 23 | Event | 1960 – The bathyscaphe USS Trieste breaks a depth record by descending to 10,911 metres (35,797 ft) in the Pacific Ocean. |
| 9652 | January 23 | Event | 1961 – The Portuguese luxury cruise ship Santa Maria is hijacked by opponents of the Estado Novo regime with the intention of waging war until dictator António de Oliveira Salazar is overthrown. |
| 9653 | January 23 | Event | 1963 – The Guinea-Bissau War of Independence officially begins when PAIGC guerrilla fighters attack the Portuguese army stationed in Tite. |
| 9654 | January 23 | Event | 1964 – The 24th Amendment to the United States Constitution, prohibiting the use of poll taxes in national elections, is ratified. |
| 9655 | January 23 | Event | 1967 – Diplomatic relations between the Soviet Union and Ivory Coast are established. |
| 9656 | January 23 | Event | 1967 – Milton Keynes (England) is founded as a new town by Order in Council, with a planning brief to become a city of 250,000 people. Its initial designated area enclosed three existing towns and twenty one villages. |
| 9657 | January 23 | Event | 1968 – North Korea seizes the USS Pueblo, claiming the ship had violated its territorial waters while spying. |
| 9658 | January 23 | Event | 1973 – United States President Richard Nixon announces that a peace accord has been reached in Vietnam. |
| 9659 | January 23 | Event | 1973 – A volcanic eruption devastates Heimaey in the Vestmannaeyjar chain of islands off the south coast of Iceland. |
| 9660 | January 23 | Event | 1986 – The Rock and Roll Hall of Fame inducts its first members: Little Richard, Chuck Berry, James Brown, Ray Charles, Fats Domino, The Everly Brothers, Buddy Holly, Jerry Lee Lewis and Elvis Presley. |