27 September – José Ballivián is sworn-in to the presidency after five days of uncertainty.[4][5]
October
1 October – Peruvian-Bolivian War: Peruvian President Agustín Gamarra begin the march to Bolivia.
2 October – Peruvian-Bolivian War: The Peruvian Army crosses the border onto Bolivian soil.
15 October – Peruvian-Bolivian War: Peruvian forces occupy La Paz without a fight.
29 October – Peruvian-Bolivian War – Battle of Mecapaca: Bolivian forces under Basilio Herrera attack those of Peru under Miguel de San Román but are repelled.
November
18 November – Peruvian-Bolivian War – Battle of Ingavi: The three competing Bolivian governments unite under Ballivián to defeat Gamarra.
Births
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