- Oct 2 Italy annexes Rome & Papal States; Rome made Italian capital
- Oct 7 Leon Gambetta flees Paris in balloon
- Oct 9 Rome is incorporated into Italy by royal decree
- Oct 13 Gustav Mahler (10) gives his 1st public piano concert
- Oct 19 1st African Americans (4) elected to US House of Representatives
- Oct 19 British steamship SS Cambria wrecked off the north-west of Ireland with the loss of 178 lives
- Oct 25 Pimlico Race Course opens in Baltimore
- Oct 25 Postcards first used in USA