| 98821 | August 31 | Event | 1798 – Irish Rebellion of 1798: Irish rebels, with French assistance, establish the short-lived Republic of Connacht. |
| 98822 | August 31 | Event | 1803 – Lewis and Clark start their expedition to the west by leaving Pittsburgh at 11 in the morning. |
| 98823 | August 31 | Event | 1813 – At the final stage of the Peninsular War, British-Portuguese troops capture the town of Donostia (now San Sebastián), resulting in a rampage and eventual destruction of the town. Elsewhere, Spanish troops repel a French attack in the Battle of San |
| 98824 | August 31 | Event | 1864 – During the American Civil War, Union forces led by General William T. Sherman launch an assault on Atlanta. |
| 98825 | August 31 | Event | 1876 – Ottoman Sultan Murad V is deposed and succeeded by his brother Abdul Hamid II. |
| 98826 | August 31 | Event | 1886 – An earthquake kills 100 in Charleston, South Carolina. |
| 98827 | August 31 | Event | 1888 – Mary Ann Nichols is murdered. She is the first of Jack the Ripper's confirmed victims. |
| 98828 | August 31 | Event | 1895 – German Count Ferdinand von Zeppelin patents his Navigable Balloon. |
| 98829 | August 31 | Event | 1897 – Thomas Edison patents the Kinetoscope, the first movie projector. |
| 98830 | August 31 | Event | 1907 – Count Alexander Izvolsky and Sir Arthur Nicolson sign the St. Petersburg Convention, which results in the Triple Entente alliance. |
| 98831 | August 31 | Event | 1913 – Police attack a union rally during the Dublin Lock-out, killing two people and injuring hundreds. |
| 98832 | August 31 | Event | 1918 – World War I: Start of the Battle of Mont Saint-Quentin, a successful assault by the Australian Corps during the Hundred Days Offensive. |
| 98833 | August 31 | Event | 1920 – Polish–Soviet War: A decisive Polish victory in the Battle of Komarów. |
| 98834 | August 31 | Event | 1920 – The first radio news program is broadcast by 8MK in Detroit. |
| 98835 | August 31 | Event | 1936 – Radio Prague, now the official international broadcasting station of the Czech Republic, goes on the air. |
| 98836 | August 31 | Event | 1935 – In an attempt to stay out of the growing turmoil in Europe, the United States passes the first of its Neutrality Acts. |
| 98837 | August 31 | Event | 1939 – Nazi Germany mounts a staged attack on the Gleiwitz radio station, creating an excuse to attack Poland the following day thus starting World War II in Europe. |
| 98838 | August 31 | Event | 1940 – Pennsylvania Central Airlines Trip 19 crashes near Lovettsville, Virginia. The CAB investigation of the accident is the first investigation to be conducted under the Bureau of Air Commerce act of 1938. |
| 98839 | August 31 | Event | 1941 – World War II: Serbian paramilitary forces defeat Germans in the Battle of Loznica. |
| 98840 | August 31 | Event | 1943 – USS Harmon, the first U.S. Navy ship to be named after a black person, is commissioned. |
| 98841 | August 31 | Event | 1945 – The Liberal Party of Australia is founded by Robert Menzies. |
| 98842 | August 31 | Event | 1949 – The retreat of the Democratic Army of Greece in Albania after its defeat on Gramos mountain marks the end of the Greek Civil War. |
| 98843 | August 31 | Event | 1957 – The Federation of Malaya (now Malaysia) gains its independence from the United Kingdom. |
| 98844 | August 31 | Event | 1958 – A parcel bomb sent by Ngô Đình Nhu, younger brother and chief adviser of South Vietnamese President Ngô Đình Diệm, fails to kill King Norodom Sihanouk of Cambodia. |
| 98845 | August 31 | Event | 1962 – Trinidad and Tobago becomes independent. |
| 98846 | August 31 | Event | 1963 – Crown Colony of North Borneo (now Sabah) achieve a self governance. |
| 98847 | August 31 | Event | 1965 – The Aero Spacelines Super Guppy aircraft makes its first flight. |
| 98848 | August 31 | Event | 1968 – Garfield Sobers became the first batsman ever to hit six sixes in a single over of six consecutive balls in first-class cricket. |
| 98849 | August 31 | Event | 1980 – After two weeks of nationwide strikes, the Polish government was forced to sign the Gdańsk Agreement, allowing for the creation of the trade union Solidarity. |
| 98850 | August 31 | Event | 1980 – Flood in Ibadan after 12 hours of heavy downpour killed over 300 people and properties worth million destroyed. |