Machaín-Irigoyen Treaty
The Machain – Irigoyen Treaty was a border treaty signed in Buenos Aires on 3 February 1876 between Paraguay and Argentina which was concluded in the aftermath of the Paraguayan War. It was signed by Facundo Machaín and Bernardo de Irigoyen.
It satisfied most of Argentina’s territorial claims and led to the complete withdrawal of Allied occupational troops from Paraguay by mid-summer of 1876. Argentina gained the disputed Misiones Province and all the lands south of the Pilcomayo River which forms Formosa Province. Argentina gave up its claims on Villa Occidental. Only the question of the Chaco Boreal (Northern Chaco) was left unresolved.[1]
Brazil had signed a separate Loizaga – Cotegipe Treaty with Paraguay already in 1872 and now did much to help Paraguay in its negotiations with Argentina. Paraguay, with Brazilian support, refused to give up Chaco territory and both sides agreed to international arbitration by the US President Rutherford B. Hayes, who on November 12, 1878 decided in favor of Paraguay. In his honor the Presidente Hayes Department was created. This decision created a scandal in Bolivia, which claimed much of the disputed Chaco region. This unresolved conflict would much later lead to the 1932-35 Chaco War.[2]