| 99661 | September 2 | Event | 44 BC – Cicero launches the first of his Philippics (oratorical attacks) on Mark Antony. He will make 14 of them over the following months. |
| 99662 | September 2 | Event | 31 BC – Final War of the Roman Republic: Battle of Actium: Off the western coast of Greece, forces of Octavian defeat troops under Mark Antony and Cleopatra. |
| 99663 | September 2 | Event | 421 – Galla Placidia, wife of the Emperor Constantius III, becomes a widow for the second time when her husband dies suddenly of an illness. |
| 99664 | September 2 | Event | 1192 – The Treaty of Jaffa is signed between Richard I of England and Saladin, leading to the end of the Third Crusade. |
| 99665 | September 2 | Event | 1649 – The Italian city of Castro is completely destroyed by the forces of Pope Innocent X, ending the Wars of Castro. |
| 99666 | September 2 | Event | 1666 – The Great Fire of London breaks out and burns for three days, destroying 10,000 buildings including St Paul's Cathedral. |
| 99667 | September 2 | Event | 1752 – Great Britain adopts the Gregorian calendar, nearly two centuries later than most of Western Europe. |
| 99668 | September 2 | Event | 1789 – The United States Department of the Treasury is founded. |
| 99669 | September 2 | Event | 1792 – During what became known as the September Massacres of the French Revolution, rampaging mobs slaughter three Roman Catholic Church bishops, more than two hundred priests, and prisoners believed to be royalist sympathizers. |
| 99670 | September 2 | Event | 1806 – A massive landslide destroys the town of Goldau, Switzerland, killing 457. |
| 99671 | September 2 | Event | 1807 – The Royal Navy bombards Copenhagen with fire bombs and phosphorus rockets to prevent Denmark from surrendering its fleet to Napoleon. |
| 99672 | September 2 | Event | 1811 – The University of Oslo is founded as The Royal Fredericks University, after Frederick VI of Denmark and Norway. |
| 99673 | September 2 | Event | 1833 – Oberlin College is founded by John Jay Shipherd and Philo P. Stewart in Oberlin, Ohio. |
| 99674 | September 2 | Event | 1856 – The Tianjing incident takes place in Nanjing, China. |
| 99675 | September 2 | Event | 1859 – A solar super storm affects electrical telegraph service. |
| 99676 | September 2 | Event | 1862 – American Civil War: United States President Abraham Lincoln reluctantly restores Union General George B. McClellan to full command after General John Pope's disastrous defeat at the Second Battle of Bull Run. |
| 99677 | September 2 | Event | 1864 – American Civil War: Union forces enter Atlanta, a day after the Confederate defenders flee the city, ending the Atlanta Campaign. |
| 99678 | September 2 | Event | 1867 – Mutsuhito, Emperor Meiji of Japan, marries Masako Ichijō. The Empress consort is thereafter known as Lady Haruko. Since her death in 1914, she is called by the posthumous name Empress Shōken. |
| 99679 | September 2 | Event | 1870 – Franco-Prussian War: Battle of Sedan: Prussian forces take Napoleon III of France and 100,000 of his soldiers prisoner. |
| 99680 | September 2 | Event | 1885 – Rock Springs massacre: In Rock Springs, Wyoming, 150 white miners, who are struggling to unionize so they could strike for better wages and work conditions, attack their Chinese fellow workers killing 28, wounding 15 and forcing several hundred mor |
| 99681 | September 2 | Event | 1898 – Battle of Omdurman: British and Egyptian troops defeat Sudanese tribesmen and establish British dominance in Sudan. |
| 99682 | September 2 | Event | 1901 – Vice President of the United States Theodore Roosevelt utters the famous phrase, "Speak softly and carry a big stick" at the Minnesota State Fair. |
| 99683 | September 2 | Event | 1912 – Arthur Rose Eldred is awarded the first Eagle Scout award of the Boy Scouts of America. |
| 99684 | September 2 | Event | 1935 – The 1935 Labor Day hurricane hits the Florida Keys, killing 423. |
| 99685 | September 2 | Event | 1939 – World War II: Following the start of the invasion of Poland the previous day, the Free City of Danzig (now Gdańsk, Poland) is annexed by Nazi Germany. |
| 99686 | September 2 | Event | 1945 – World War II: Combat ends in the Pacific Theater: The Japanese Instrument of Surrender is signed by Japanese Foreign Minister Mamoru Shigemitsu and accepted aboard the battleship USS Missouri in Tokyo Bay. |
| 99687 | September 2 | Event | 1945 – Vietnam declares its independence, forming the Democratic Republic of Vietnam. |
| 99688 | September 2 | Event | 1946 – The Interim Government of India is formed, headed by Jawaharlal Nehru as Vice President with the powers of a Prime Minister. |
| 99689 | September 2 | Event | 1957 – President Ngô Đình Diệm of South Vietnam becomes the first foreign head of state to make a state visit to Australia. |
| 99690 | September 2 | Event | 1958 – United States Air Force C-130A-II is shot down by fighters over Yerevan in Armenia when it strays into Soviet airspace while conducting a sigint mission. All crew members are killed. |