1866 in Argentina

← 1865 1864 1863 1866 in Argentina → 1867 1868 1869
Decades:	1840s 1850s 1860s 1870s 1880s
See also:	Other events of 1866 List of years in Argentina

Events in the year 1866 in Argentina.

Incumbents

• President: Bartolomé Mitre
• Vice President: Marcos Paz

Governors

• Buenos Aires Province: Mariano Saavedra (until 1 May), Adolfo Alsina (starting 1 May)
• Mendoza Province:
  • until 1 November: Carlos González
  • 1 November-11 November: Melitón Arroyo
  • starting 11 November: Carlos Juan Rodríguez
• Santa Fe Province: Nicasio Oroño

Vice Governors

• Buenos Aires Province: vacant

Events

• January 31 – Paraguayan War: The Battle of Pehuajó takes place when about 1500 Paraguayan troops, commanded by General Francisco Isidoro Resquín and Lieutenant Celestino Prieto, engage in a surprise attack Argentinian and Uruguayan battalions with around 2000 men, led by General Emilio Conesa; the Paraguayans are successful and the joint Argentine-Uruguayan force suffers heavy casualties.
• May 24 – Paraguayan War: First Battle of Tuyutí is an allied victory.
• July 18 – Battle of Boquerón (1866)
• September 1–3 – Battle of Curuzú
• September 22 – Battle of Curupayty

Deaths

• February 15 – Juan Gregorio de las Heras, military leader (born 1780)