Chaco War (1932-1935): Bolivia and Paraguay's Desert War

The Chaco War was fought between Bolivia and Paraguay from 1932 to 1935 for control of the Chaco Boreal, a hot, dry and thinly populated plain in the heart of South America. It was the bloodiest war between two states in the Americas in the twentieth century, with total deaths commonly estimated at between about 85,000 and 100,000. Paraguay, the smaller country, won, but both nations were transformed by the political crises that followed.

Causes

The boundary between Bolivia and Paraguay in the Gran Chaco had never been settled after independence from Spain. The region was mostly scrub forest and grassland, scorching in summer and almost waterless in the dry season, inhabited mainly by Indigenous peoples and a few Mennonite settlers, ranchers and tannin companies.

Both countries had reasons to want it. Paraguay, devastated by the Paraguayan War of 1864-1870, regarded the Chaco as part of its national territory and had sold or leased much of it to private interests. Bolivia had lost its Pacific coast in the War of the Pacific and hoped to reach the Paraguay River, and through it the Atlantic. Oil had been found in the Andean foothills on the Bolivian side, and many believed more lay beneath the Chaco.

From the 1920s both armies built small forts (fortines) ever deeper into the disputed land. Clashes occurred in 1928, and diplomacy failed to resolve the dispute.

Course of the war

In June 1932 a Bolivian detachment seized a Paraguayan post at Laguna Pitiantuta. Paraguayans retook it, and Bolivia’s president, Daniel Salamanca, ordered the capture of several Paraguayan forts in retaliation. Paraguay mobilised, and full-scale war began with its siege of the Bolivian fort at Boquerón on 9 September 1932. The fort surrendered on 29 September. Paraguay formally declared war in May 1933.

Bolivia had a larger population, more money and modern equipment, including aircraft and tanks, and its army was led from late 1932 by the German general Hans Kundt. But its supply lines from the Andes were long, and many of its soldiers were Indigenous highlanders unused to the lowland heat. Paraguay’s commander, José Félix Estigarribia, used mobile tactics, flanking movements and encirclements, and Paraguay could supply its troops by river and railway.

Bolivian frontal assaults on the fortified Paraguayan position at Nanawa in January and July 1933 failed with heavy losses. In December 1933 Paraguay encircled two Bolivian divisions at Campo Vía, capturing thousands of men, and Kundt was dismissed. A short truce over Christmas did not lead to peace.

In 1934 Paraguayan forces advanced north-west across the Chaco. At El Carmen in November 1934 they trapped another large Bolivian force. Days later Bolivian officers forced President Salamanca to resign at Villamontes. By 1935 the Paraguayans had reached the edge of the Andean foothills and threatened Bolivian oil fields, but their supply lines were now overstretched and Bolivian resistance stiffened.

Soldiers and fighting

Most soldiers on both sides were conscripts. Bolivia’s army drew heavily on Aymara and Quechua peasants from the highlands, who suffered badly in the heat of the lowlands, while Paraguayan troops often communicated in Guaraní, the Indigenous language spoken by most of the population. The war saw early use in South America of military aircraft, trucks and machine guns on a large scale, but most fighting still took place on foot in dense scrub. Its experiences later inspired novels such as Augusto Céspedes’s Sangre de mestizos (1936) in Bolivia and Augusto Roa Bastos’s Hijo de hombre (1960) in Paraguay.

The human cost

Water was the decisive factor in many battles. Soldiers died of thirst in the bush when wells were captured or supplies failed, and malaria, dysentery and exhaustion killed many more. Estimates usually put Bolivian deaths at about 50,000-65,000 and Paraguayan deaths at about 30,000-40,000, from populations of roughly 2-3 million and under 1 million respectively. Tens of thousands of prisoners were taken, especially by Paraguay.

Peace

Under pressure from neighbouring countries, a ceasefire was signed on 12 June 1935 and took effect two days later. A peace conference in Buenos Aires, led by the Argentine foreign minister Carlos Saavedra Lamas, produced a treaty on 21 July 1938. An arbitration award later that year gave Paraguay about three-quarters of the Chaco Boreal, while Bolivia kept a corridor towards the Paraguay River and its oil-producing foothills. Saavedra Lamas received the Nobel Peace Prize for 1936. The border was finally demarcated by an agreement signed in 2009.

Consequences and legacy

In Bolivia, defeat discredited the traditional elite. Young officers seized power in 1936, and in 1937 the government nationalised the Bolivian holdings of Standard Oil, the first such expropriation in Latin America. The war generation’s anger fed new nationalist and left-wing movements that culminated in the Bolivian National Revolution of 1952.

In Paraguay, victory did not bring stability. Discontented veterans backed the February Revolution of 1936, which overthrew President Eusebio Ayala. Estigarribia, the war’s hero, became president in 1939 but died in an air crash in 1940.

Timeline

• 1932, 15 June: Bolivian forces seize the Paraguayan post at Laguna Pitiantuta.
• 1932, 9-29 September: Paraguay besieges and takes Boquerón.
• 1933, January and July: Bolivian assaults on Nanawa fail.
• 1933, 10 May: Paraguay formally declares war.
• 1933, December: Paraguayan victory at Campo Vía.
• 1934, November: Paraguayan victory at El Carmen; Salamanca is forced from office.
• 1935, 12 June: Ceasefire signed.
• 1938, 21 July: Peace treaty signed in Buenos Aires.

Why it matters

The Chaco War showed how a remote border dispute could become a modern war of attrition, fought in some of the harshest conditions on Earth. It reshaped the politics of both countries and remains a central event in Bolivian and Paraguayan national memory.