was submitted to arbitration. The arbitrator chosen by both nations was US President Rutherford B. Hayes, who awarded Central Chaco to Paraguay in 1878. The Argentine army left in May 1879. In gratitude, Paraguay renamed the department as "Presidente Hayes" and the capital as "Villa Hayes". Bolivia The 1864-1870 war eventually settled the boundary disputes in the Chaco, but not between Paraguay and Bolivia, which continued to fester. In 1931 Bolivian oil hunger caused its military to invade the disputed area, leading to the Chaco War. (There turned out to be no oil worth fighting over.) The Paraguay-Bolivia boundaries were not finally resolved until a treaty of 28 April 2009. See also Fortress of Humaitá Paraguayan War Paraguayan War casualties Paraguay expedition Women in the Paraguayan War Notes References (ebook) External links English language text of the Treaty of the Triple Alliance (British Parliamentary translation of Uruguayan text) Brazilian text of the Treaty (in Portuguese) Argentine text of the Treaty (in Spanish) Paraguayan War Military alliances involving Argentina Military alliances involving Brazil Military alliances involving Uruguay 1865 in Argentina 1865 in Brazil 1865 in Uruguay 19th-century military alliances Triple Alliance Argentina–Brazil relations Triple Alliance Triple Alliance May 1865 events