The Chaco War was the first major Latin American conflict in which aircraft were used. This aerial war carried a large human and materiel cost. At that time, Bolivia possessed one of the greatest aerial forces in the region, however this fact did not prevent its final defeat. Bolivia lacked the expertise to utilise its aerial forces, and was thus unable to maximise its use of military aviation. Paraguay had a small number of pilots and technicians, all veterans of the revolution of 1922. The 1922 revolution was a brief civil war in which the government and the rebels used aircraft in the operations, and José Félix Estigarribia could be considered an innovator in the military use of aircraft on the continent.
Background Between July and August 1932, the Paraguayans built a landing strip at the advance base of Isla Poi and deployed a small force of combat aircraft for reconnaissance purposes, which was practically all the military aircraft which Paraguay possessed. Bolivia's air force was numerically superior, but was limited by the lack of airfields close to the combat zone. Despite this disadvantage, the Bolivian Army Air Corps was able to conduct attacks in a relatively effective manner.
Lieutenant Colonel Bernardino Bilbao Rioja took charge of the Bolivian Air Corps in the Chaco and initiated the operations in July 1932, concentrating his forces on the primary base of Villa Montes, out of an advanced base in Muñoz, nowadays Fort General Díaz, in Paraguayan territory.
Fighter and Fighter bombers First acquisitions
In July 1932, the Bolivians deployed three Vickers Vespa combat aircraft, three Breguet XIX bombers, and three Vickers Type 143 fighters from their forward airfields. By early 1933, the Bolivian army had acquired a consignment of 20 Curtiss-Wright CW-14 Osprey. Paraguay ordered seven Potez 25s through the French military mission, the aircraft arriving in October 1928. Even before the final delivery, one Potez was lost when, while still crated, it was accidentally dropped overboard during the trans-shipping operation in Montevideo, Uruguay. The seventh Potez 25 was replaced by the French company in 1932. Intensive training from 1928 to 1931 resulted in 25 pilots and 18 maintenance personnel ready for operating the aircraft. The First Squadron of Bombing and Reconnaissance was established by the beginning of the war, made up of the seven Potez 25s and two Wibault 73.Hagedorn & Sapienza, pp. 30-31 At least ten Curtiss P-6 Hawk fighters bought by Bolivia were delivered between December 1932 and March 1935.Hagedorn & Sapienza, pp. 67-68 The Bolivian army was familiar with the Hawks since a 1928 demonstration carried out in La Paz by no other than Jimmy Doolittle, who later tried to take off in a float-fitted Hawk from Lake Titicaca without success.Hagedorn & Sapienza, pp. 66 The fighter of choice for the Paraguayan air branch was the Fiat CR.20, acquired through the Italian legation. Five aircraft were delivered in April 1933. The warplanes were declared operational on 25 May 1933, and arrived to the front the next day.Hagedorn & Sapienza, pp. 74-75
Operational history Given the potential of the Bolivian Ospreys, Lt Col Bilbao visited the Commander in chief, Colonel Enrique Peñaranda Castillo, and suggested to him that the best use of the Bolivian Air Force was to bomb the main Paraguayan base at Puerto Casado on the Paraguay river, given that every man, car, horse, and munition used this point to enter the Chaco theatre of operations.
Later, in a violent confrontation with Colonel Peñaranda, Bilbao Rioja insisted on bombing Asunción in order to demoralise the Paraguayans. From the airstrips at Muñoz and Ballivián, the Bolivian Air Force could reach Asunción and Puerto Casado. The Bolivian high command disapproved of Bilbao Rioja's demands as they thought, not incorrectly, that bombing Asunción would cause international outcry against Bolivia. At the time of the war, the Bolivian high command saw no profit in taking such dramatic steps, though the Bolivians came to reconsider this later.
However, they authorised various incursions against the Paraguayan bases at Puerto Casado. These incursions provoked a strong reaction on the part of the Argentine government, as many Argentines lived and worked in Puerto Casado and managed the key railway that linked that city with the Chaco heartlands (and thus supported the Paraguayan military campaign).
Argentina, though officially neutral during the war, maintained a status that could be described as "amiable neutrality" towards the Paraguayans, even offering them financial support. After the air strike on Puerto Casado in 1933, the Argentines told the Bolivians that they would not tolerate further attacks on their civilians, implying that they might be inclined to support the Paraguayans if such attacks continued. Faced with this dilemma, Bolivia sensibly discontinued aerial attacks. From this point in the campaign, the Bolivian Air Corps was used primarily for reconnaissance missions on the front lines, for aerial patrols and close air support.
From the beginning, Bilbao Rioja ordered the aircraft to conduct aggressive patrols over the Chaco, and the Bolivians lost at least one Vickers Vespa due to anti-aircraft fire at the end of July.Hagedorn & Sapienza, p. 43 During the Battle of Boquerón, both sides carried out numerous attacks in support of ground troops.
Between 9 and 29 September, Paraguayan Potez 25s, escorted by Wibault 73 fighters, carried out 12 bombing raids against Bolivian troops in Boqueron. The Paraguayans also used their radio-equipped Potez 25s to direct artillery fire from their Schneider 75 mm batteries.
Though both sides flew reconnaissance and close air support missions during the Boqueron Campaign, there is disagreement about the first air-to-air confrontation: According to Paraguayan reports, this occurred on 28 September, when a Paraguayan Potez 25 encountered a Bolivian Vickers Vespa. The Paraguayan pilot, Lieutenant Emilio Rocholl, was wounded but able to return to base with his aircraft.Hagedorn & Sapienza, p. 31 According to Bolivian accounts, the first aerial combat on the Americas between belligerent nations occurred on 4 December 1932, over Saavedra.Hagedorn & Sapienza, p. 32 The victor was Bolivian pilot Rafael Pabón, who shot down a Paraguayan Potez TOE Nº 6. This was the pilot's only victory against a Paraguayan aircraft, despite Bolivian claims of other two victories. While he was seeking a second victory, he was taken out by a Potez 25 TOE N° 11, dying there with his gunner on 12 August 1934 near Fort Florida. Upon discovering the identity of the pilot, the Paraguayans paid the dead pilot great honours.Hagedorn & Sapienza, p. 25
The first encounter between fighters over the Chaco took place on 12 June 1933, as five Ospreys were being escorted by three Hawks and one Vickers Scout in the course of an airstrike against Isla Poí. The Fiats disrupted the Bolivian package in the middle of a furious dogfight. Lieutenant Walter Gwynn's CR.20, however, crashed in the aftermath, killing the pilot. A Paraguayan technical team ruled out hostile fire as the cause of this loss.Hagedorn & Sapienza, pp. 76-77 The Fiats engaged the Ospreys again on 23 September 1934 over Picuiba, when two Bolivian warplanes were spotted while involved in a bombing mission. One of the Ospreys jettisoned its bombs and escaped unscathed, but the other pilot only became aware of the enemy fighters when he noticed the loss of his wingman. The Fiats duly targeted the lonely plane with their machine guns. The Paraguayans claimed the second Osprey as "probable", but the Bolivian aircraft managed to fly back to its base, although seriously damaged.Hagedorn & Sapienza, pp. 77-78 The Paraguayan army would lose another Potez 25 to Bolivian planes on 12 December 1934 over Capirenda, when a Hawk escorting a Junkers K 43 shot down Potez TOE Nº 13 after a brief exchange of fire. Both pilot and gunner survived the crash.Hagedorn & Sapienza, p. 36 The conflict would see the last ever dogfight between biplanes, over the Bolivian stronghold of Ballivián.John Gimlette. At the Tomb of the Inflatable Pig: Travels Through Paraguay. Knopf (January 6, 2004). page 336. or The Potez 25 would be the only type of aircraft from either side to be used during the entire conflict.Hagerdon & Sapienza, p. 37
Aerial support The aerial forces played a variety of important roles at all stages of the war, including close air support, reconnaissance, air supply and evacuation of the wounded.
Though the aerial combat and bombardier units gained the most glory, the unarmed transport and general-use aircraft of both air forces played a key role in the war. Both sides used a variety of transport and light aircraft to support their forces. Paraguayan planes would drop water to their own thirsty troops in the form of ice blocks,Gimlette, p. 336 a tactic developed by the Bolivians during the siege of Boquerón.Guachalla, Luis Fernando (1978). Jayucubás: comentários y crónicas de la Guerra del Chaco. Editorial Los Amigos del Libro, p. 342 The Potez 25 played the role of transport aircraft during the first and second battles of Nanawa, when they replenished the depleted Paraguayan stockpiles with hand grenades and ammunitions. by General Fulgencio Yegros Girola The four Potez 25s involved in the operation were stripped of their rear machine guns in order to use the gunner's cockpit to load 115 kg of ammunition. The aircraft departed from Isla Poí to the south over Bolivian-controlled areas. On the first day only, they delivered 1,650 kg of ammunition on a hastily built runway. Three of the planes were hit by ground fire and forced to make emergency landings, but all of them were recovered and shipped to Asunción, where they endured a major overhaul.Hagedorn & Sapienza, pp.32-33
Meanwhile, the Bolivian Ospreys became major players on the Bolivian victory at Cañada Strongest when aerial reconnaissance from Ballivian uncovered a new Paraguayan trail through the woods aimed to encircling two Bolivian divisions west of Cañada Esperanza.Hagedorn & Sapienza, p. 24
At the start of the war, the Bolivian military forces employed Lloyd Aéreo Boliviano (LAB) civilian airliners, including four light transport aircraft Junkers F-13 (single engine, six passenger) and three Junkers W 34 transport aircraft. Some Junkers F-13 would be converted into seaplanes by the Bolivian army.Hagedorn & Sapienza, p. 91 The LAB had recently included a Ford Trimotor, using it as a transport aircraft, which was destroyed in an operational accident while taking off at Villa Montes.Hagedorn & Sapienza, p. 106
In December 1932, Bolivia received from Germany three tri-motor Junkers Ju 52, bought with a loan from Bolivian tin tycoon Simón Patiño. A fourth aircraft arrived in February 1935. The durable construction of the Ju 52, with its three tons payload, made it an ideal aircraft for flights in South America. The Bolivians counted on a substantial air transport force, and the conditions of logistics in the Chaco demanded that such capabilities be used to the maximum in order to transport the necessary munitions, combustibles, and medicine to the front. During the war, the Ju 52 alone transported more than 4,400 tons of cargo to the front.Hagerdon & Sapienza, pp. 96-100
Aerial medical evacuation Paraguay also pressed a wide variety of transport and general-use aircraft into service. At the end of 1932, Paraguay had purchased two Travel Air 6000 six-passenger aircraft from the United States, to serve as aerial ambulances. Both aircraft were christened Nanawa. During the war, both sides used aircraft for the transport of the sick and wounded from the front-line airstrips to the field hospitals in the rear. Over the course of the war, the Bolivian Ju 52's evacuated over 40,000 Bolivian troops from the front lines .