| 12 October 1509 | Holy Roman Empire, Italy [political events] | The Holy Roman Emperor Maximilian I, unable to take Padua from its populace, retreats from Italy for the Tirol. |
| 12 October 1537 | England [political events] | Jane Seymour, the third wife of King Henry VIII of England, gives birth to Prince Edward, but dies 12 days later. |
| 12 October 1576 | Holy Roman Empire, Habsburg Monarchy [political events] | The Holy Roman Emperor Maximilian II dies and is succeeded in all his lands and titles by his son, Rudolph II. A patron of the Jesuits, Rudolph is markedly more supportive of the Catholic Counter-Reformation than the Protestant-leaning Maximilian. |
| 12 October 1716 | Hungary, Habsburg Monarchy, Ottoman Empire [Habsburg–Ottoman Wars (1525–1718)] | Austrian forces under Prince Eugène of Savoy take Temesvár (now Timisoara, Romania), the fortress that has resisted Habsburg advances for 164 years in the Banat, the last Ottoman possession in Hungary. |
| 12 October 1813 | Persia, Russian Empire [treaties] | By the peace of the Treaty of Gulistan, Persia cedes the Caucasus region to Russia, continuing the extension of Russian influence southwards. |
| 12 October 1822 | Brazil, Portugal [decolonization] | Brazil becomes formally independent of Portugal and Dom Pedro is proclaimed Emperor Pedro I. |
| 12 October 1866 | Scotland [births and deaths] | Ramsay MacDonald, British politician, first Labour Party prime minister of Britain 1924, prime minister again in 1929, and in a coalition government 1931–35, born in Lossiemouth, Moray, Scotland (–1937). |
| 12 October 1870 | USA [births and deaths] | Robert E Lee, Confederate general who commanded the Southern armies during the American Civil War, dies in Lexington, Virginia (63). |
| 12 October 1899 | South Africa [Anglo–Boer Wars (1899–1902)] | A Boer ultimatum demanding Britain stop sending troops to southern Africa expires and the Second Anglo-Boer War begins. |
| 12 October 1920 | Russia, Poland [treaties] | Russia and Poland sign a peace treaty to end their war, at Tartu, Estonia, signing a full treaty on 18 March 1921. |
| 12 October 1984 | UK [terrorism] | An Irish Republican Army (IRA) bomb explodes at the Grand Hotel, in Brighton, England, during the Conservative Party conference, killing 4, injuring 32, and narrowly missing the British prime minister Margaret Thatcher. A fifth victim dies on 13 November. |
| 12 October 2003 | Japan [motor-racing and rallying] | Germany's Michael Schumacher clinches a record sixth world formula one motor racing championship following the Japanese grand prix at Suzuka. |
