page_title: Treaty of the Triple Alliance
section_title: Background
hierarchical_section_title: Treaty of the Triple Alliance / Background
caption_attribution_description: Map showing the Río de la Plata drainage basin including major tributaries and cities.
context_page_description: The Treaty of the Triple Alliance was a treaty that allied the Empire of Brazil, Argentina, and Uruguay against Paraguay. Signed in 1865, after the outbreak of the Paraguayan War, its articles prescribed the allies' actions both during and after the war. The war led to the near-annihilation of Paraguay.
  After the defeat of Paraguay, Brazil and Argentina hovered on the brink of mutual warfare for 6 years because of disputes and misunderstandings about the Treaty.
context_section_description: Although the Empire of Brazil and Argentina were traditional enemies, they, together with Uruguay, united against Paraguay in 1865. The causes of the war were various and have been hotly disputed by modern writers, but for the purposes of this article, it may be enough to outline the geopolitical situation and the immediate antecedents of the treaty.
  
  In the middle of the 19th century, vast tracts of South America were undeveloped, railways were few and short, and made roads practically did not exist.  So navigable rivers were "vital arteries".  Of particular relevance were the River Paraná and the River Paraguay.  Using the Paraná-Paraguay system, quite large ships could steam 1,870 miles (3,010 km) upriver from Buenos Aires well into the Brazilian Mato Grosso.   These rivers were of crucial importance to landlocked Paraguay, to Brazil and to the trade of some Argentine provinces.  It was, wrote D.S. Chandler 
  a region which needed only peaceful intercourse and open rivers for rapid economic growth to transform the lives of its inhabitants. Unfortunately, after the onset of the independence era those conditions seldom offered themselves for more than a few years at a time.  Wars and political and economic rivalries meant that more often than not, high tariffs and blockades vexed the river system. 
   Thus Buenos Aires Province under Juan Manuel de Rosas had restricted river traffic to put pressure on upstream Paraguay, and Paraguay under Carlos Antonio López had done the same to put pressure on Brazil.
  Furthermore, immense territories were disputed. Not effectively occupied by anyone, except the aboriginal inhabitants, they had no obvious international boundaries.  There was a boundary dispute between Brazil and Paraguay going back to colonial times, and there were large areas in dispute between Paraguay and Argentina in the Gran Chaco and in the territory of Misiones.  Then, there were no obvious and accepted principles according to which they might have been resolved, and no established practice of international arbitration existed.  In international law, victory in war was a recognised mode of acquiring territory.
  In 1855 Paraguay, with an understandable fear and distrust of its neighbours, began to develop the formidable Fortress of Humaitá. Established near the mouth of the River Paraguay and known as the Gibraltar of South America, it was the gateway to the country. However, it may have caused the Paraguayan government to feel itself invulnerable (wrongly, as it turned out), and it caused tension with Brazil. As explained by Lieutenant Colonel George Thompson of the Paraguayan Army:
  
  Paraguay made all vessels anchor and ask permission before they could pass up the river. As this was the only practicable road which Brazil had to her province of Matto-Grosso [sic], she naturally disapproved of her stoppage of the river, and gradually accumulated large military stores in Matto-Grosso, with the view, no doubt, of some day destroying Humaitá.
  Between 1854 and 1864, and supervised by Francisco Solano López, the president's son, Paraguay built up its military forces because it thought that the outside world (in particular Brazil, Argentina, the United States, and the British Empire) was disrespecting it.  Paraguay imported some 200 foreign technicians, mostly British, and  developed an iron foundry, an arsenal, a shipyard, a telegraph and a railway.  All this modernisation was military.  It also imported from Britain the cadre of a military medical corps who trained Paraguayan medical students. Thus Paraguay became an important regional power.  However, wrote John Hoyt Williams, "The dizzying speed with which his nation was 'modernized' and strengthened tempted López to flex his new muscle and seek an ever-expanding, activist role in international affairs.". López became ruler of Paraguay in September 1862 after the death of his father.
  In 1862, the Blanco Party (Uruguay), traditionally hostile to Brazil, and now alarmed because its bitter enemies had seized power in Buenos Aires too, felt itself to be acutely short of all
caption: Vital arteries.  The free navigation of the rivers Paraná and Paraguay had long been disputed by contending powers. (The boundaries shown here are present day.)
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