Tank warfare in the Chaco War

The Chaco War (1932–35), between Bolivia and Paraguay, was the first South American conflict in which tanks were used. They were used exclusively by Bolivia, due to its stable economy based on mining gold, silver, and tin.

The first Bolivian Vickers
Anticipating imminent armed conflict with Paraguay, in 1926 Bolivia signed a large contract with Vickers Armstrong worth 3 million pounds sterling. At the insistence of General Hans Kundt, this initially included a dozen tanks, as well as other military equipment. Though this contract was later reduced to less than 1.25 million pounds sterling due to the crisis of 1929, this still included a small quantity of tanks and tankettes, as well as rifles, machine guns, artillery, and aircraft.

The Vickers light tanks were well-built military machines, though while the chassis was of excellent design, the design of the superstructure and turret were rather rougher. This led some countries to focus on improving those parts. All of these examples maintained the Vickers suspension, which was copied by many countries. There were many variants on the Vickers light tank, but those bought by Bolivia were the Type A and Type B, which differed only in the turret type. The tanks were commissioned into the Bolivian army in December 1932, and were originally painted in camouflage patterns. Their factory numbers were VAE532 for the Type A and VAE446 and VAE 447 for the Type Bs.

The Type A had twin cylindrical turrets, and were armed with two armour-protected Vickers 7.65mm water-cooled heavy machine gun. The turrets were mounted side-by-side, each covering 120° to each side of the longitudinal axis of the tank. These were crewed by four people: two machine gunners, a commander, and a driver. In contrast the Type B had a single truncated turret, and was armed with a short, low-velocity QFSA 47mm cannon and a coaxial 7.65 water-cooled machine gun (apparently a variant of the Vickers LMG with the barrel installed in heavy armour protection). The turret was a rough truncated design with a circular horizontal section and a trapezoidal vertical session. This turret contained two crew members, a commander and a gunner, who also served as a loader. The tanks were fitted with a 2 channel radio set, whose use was hampered by the wet environment. They also received at least two Carden-Lloyd tankettes armed with Vickers 7.65mm machine guns. These vehicles had not originally been designed as assault vehicles, but as mobile platforms for emplacing machine guns on the battlefield. However, improvements in the design of the mounting of the pieces allowed them to act as mobile firing platforms. Its armor was minimal and offered little protection for the crew, while its area of fire was very limited as the machine gun was fixed facing forward on the vehicle.

These vehicles were the first armored vehicles used by Bolivia. The Renault FT-17 was also reported to have been employed by Bolivia in the Chaco War, though this has not been proven. At least one demonstration unit arrived in La Paz in 1931, but it was never deployed to the Chaco. With this, Bolivia became the first South American country to possess tanks and use them in combat. Between the end of the fighting in 1935 and the signing of the Peace Treaty in 1938, Bolivia acquired a dozen Ansaldo L3/35 tankettes from Italy, whose design was also based on the Carden-Lloyd.

Combat history
The Bolivian Army had a few German instructors, that formed part of the numerous German missions which evaded the clauses of the Treaty of Versailles, and provided services to Bolivia as early as 1911. Some of these, such as Major Wilhelm "Wim" Brandt and Major Achim R. von Kries commanded some of the Bolivian tanks, with the rest of the crew drawn from Bolivian volunteers with eight weeks of training. Brandt would be killed in action in World War II after joining the Waffen SS, while von Kries would be seriously wounded in the Second Battle of Nanawa. Another foreigner recorded as having commanded tanks was Austrian Major Walter Kohn (aka John Kenneth Lockhart). He died on 27 December 1933 during the battle of Kilometer 7 to Saavedra, while taking part as an infantryman in the assault on a machine gun nest. At least two of the mechanics of the armoured unit were Chileans.

The armoured assets entered combat for the first time on 13 September 1932 near Boquerón, when  a Carden-Lloyd tankette, commanded by Kohn, tried to break the perimeter at Yujra to aid Colonel Marzana's troops. Major Kohn was later killed after leaving the tankette in the mid of a Bolivian offensive at Kilometer 7, due to heat, to fight on foot, as said above. The Carden-Lloyd had been supporting infantry patrols in no-man's-land before the battle, and at the time of Kohn's death it had been carrying a flamethrower. The Vickers 6-ton achieved some success during the Second Battle of Nanawa, when a Type B tank broke into the core of the Paraguayan defenses, after wiping out a number of wooden pillboxes. The other Type B was left behind by the Bolivian Army after its transmission was damaged by an artillery round. The derelict tank was ultimately blown up by Paraguayan sappers on 8 July. Its 47mm gun turret was removed by Paraguayan technicians and exposed in the War Museum at Asunción. Although the Paraguayan infantry was not match for the Vickers, Bolivian reports acknowledge that small-arms fire ricocheting the tanks sapped their crews' morale. The twin-turret tank also sustained some damaged from a volley of rifle fire, while virtually all tanks crewmen suffered injuries of different degree from bullet splinters. The Paraguayan army used 7.62mm armour-piercing rounds during the engagement. As for the tankettes, they were withdrawn from the frontlines in July, after being disabled at Nanawa, one by machine-gun fire, the other when becoming stuck in a ditch.

The surviving tanks led a successful thrust which overran the enemy outpost of Pirijayo –Pirizal for the Paraguayans– on August 1933. After this action, the Type A was placed in an open area in order to keep at bay any Paraguayan counterattack from the nearby woods, while the Type B was driven back to the rearguard due to mechanical failure. The last operational use of the Vickers took place on 15 November, when the Type A's machine guns defeated an assault of the Paraguayan infantry near Alihuatá. The tanks were eventually ambushed and captured during the battle of Campo Vía on 10 December 1933 by a squadron of the Cavalry Regiment "General San Martin", made up mostly of Argentine volunteers. The Type A was on display as part of a war memorial in Constitution square at Asunción until 1990, when the tank was returned to Bolivia, along with the turret of the Type B destroyed at Nanawa. The second Type B was sold by the Paraguayan government to the Republican side of the Spanish Civil War in January 1937. <!-- Los tanques nuevamente intervinieron en la batalla del 4 de julio de 1933 en "Nanawa". Operando en dos grupos, uno dotado de dos tanques (un tanque Type A y un Type B) y otro formado por el Type B restante y las 2 Carden-Loyd. Durante el segundo ataque, los blindados estuvieron flanqueados inicialmente también por soldados bolivianos armados con lanzallamas alemanes Modelo 1918 y recibieron algún apoyo de la aviación. Sin embargo, muy pronto las unidades quedaron aisladas de la infantería y tuvieron que retirarse. El Type B al mando de Kohn fue inmovilizado por un impacto artillero cerca a Punta Mojoli (se supone que se trató de un proyectil de 75 mm de un cañón Schneider que pentro bajo la torreta, aunque otras versiones también hablan de que se trató del impacto de una granada de mortero Stokes-Brandt de 81 mm que penetró por las escotillas), perdiendo asi la vida el cap. Kohn. La infantería boliviana intentó en repetidas ocasiones recuperar el vehículo, pero cuando esto se hizo imposible, la artillería intentó destruirlo, fallando pese a lograr impactos directos sobre el chasís del mismo con piezas de 65 y 75 mm. El tanque fue finalmente destruído 4 días después, mediante una potente carga explosiva colocada debajo del mismo. Aún se discute si esta fue colocada por los paraguayos para impedir la recuperacion del blindado, ya que los zapadores bolivianos venían cavando una zanja hacia este, o por los bolivianos para impedir su captura, debido a su proximidad a las líneas paraguayas (menos de 60 metros). Al menos uno de los blindados, comandado en esta ocasión por el Sub.Of. Saavedra Acha, logró ingresar al reducto de Nanawa, viendose forzado a retroceder cuando la infantería de apoyo no logró acompañar su ingreso al fortín y este se vio en peligro de ser rodeado e inmovilizado.

Los Vickers Mk.E disponían de un aparato de radio de dos canales, pero debido al calor y humedad extremos, quedaron rápidamente inutilizados y no prestaron ninguna utilidad. El Type B (con su cañón de 47 mm) se especializó en hacer estallar los nidos de ametralladoras y los fortines de quebracho paraguayos, siendo prácticamente invulnerable al fuego de los defensores. Por lo cual, los paraguayos formaron unidades especializadas para dar caza a los tanques bolivianos, especialmente los Mk.E. Así fue como su artilleria logró inmovilizar uno, mientras que una unidad de caballeria (R.C.7 San Martin) logró capturar los dos restantes al bloquear su avance talando árboles de quebracho por delante y por detras de su ruta el dia antes de la rendicion de "Campo Vía". El calor imperante hizo que después de unas pocas horas, ambas tripulaciones al mando de Brandt y von Kries se rindieran.

La movilidad de los tanques en el Chaco era muy complicada debido al terreno suelto y poco compacto, al clima y la falta de combustible. La ya escasa gasolina era entregada con prioridad a los camiones que transportaban suministros, pertrechos, tropas y heridos. Como consecuencia del calor del verano (de 40°C a la sombra y hasta 60° dentro del vehículo), las unidades solían desplazarse con todas las escotillas abiertas, exponiendo a la tripulación incluso al fuego de fusil y ametralladoras ligeras. En estas circunstancias también se producía el encasquillamiento de las ametralladoras Vickers con que iban armados, debido a que los cartuchos se dilataban y no eran expulsados de la recámara. Además era imposible tocar las partes metálicas de las armas para destrabarlas sin usar guantes, pues quemaban.

Destino de los Vickers
La cantidad total de tanques Vickers Mk.E en servicio de Bolivia se discute entre 3 y 6 unidades. El proyecto inicial consideraba la compra de un total de 12, pero los recortes presupuestarios resultantes de la crísis de 1929 redujeron sustancialmente esta cantidad. Se tienen datos precisos de la presencia y actuación en el Chaco de 3 Vickers Mk.E (1 Type A, 2 Type B) y 2 tanquetas Carden-Loyd Mk.IVb en la campaña de Nanawa. Se habla también del arribo a Bolivia de un segundo Type A y un par de semitractores de artilleria Vickers, que nunca se habrian enviado al Chaco, pero no se conservan registros de esto.

El destino de los tanques se ha discutido extensamente. Sin embargo es seguro es que un tanque Type B fue inmovilizado por la artilleria paraguaya (probablemente una pieza Schneider de 75 mm o como comentan algunos excombatientes, una granada de mortero Stokes-Brandt de 81 mm) y luego fue destruído con explosivos durante la seguna batalla de Nanawa, mientras los otros 2 fueron capturados por el R.C.7 del Paraguay en el cerco de Campo Vía.

Algunas de las armas bolivianas capturadas por el Ejército paraguayo junto con un lote de fusiles Mauser Oviedo Mod. 1927 (los famosos 'Mataparaguayos') fueron vendidas por el gobierno del Cnel. Rafael Franco al bando Republicano durante la Guerra Civil Española, entre ellos el tanque Vickers Mark E Type B con número de serie VAE 446, dotado con una ametralladora pesada de 7,65 mm y un cañón semiautomático de 47 mm. Si bien está confirmado su arribo a España (según la lista Howson, el tanque arribó el 30 de septiembre de 1937 a bordo del Ploubazla), no se han encontrado informes sobre su empleo en combate. El otro tanque capturado, un Type A, tras ser usado por algunos años, acabó como monumento en una plaza y fue devuelto a Bolivia en 1994. También se devolvió la torreta del Type B destruído en Nanawa. Ambos están ahora expuestos en el Museo Militar de Bolivia.

Del destino de las tanquetas Carden-Loyd no se tienen datos tras la Segunda Batalla de Nanawa. Existe la certeza de que ambas participaron en la ofensiva y al menos una se atascó en una trinchera paraguaya. Por la falta de registros posteriores de su presencia, se cree que ambas se perdieron en esta ocasión. Una habría sido seriamente dañada por el fuego de ametralladoras pesadas paraguayas (Maxim o Colt) de 7,65 mm alimentadas con munición antiblindaje, mientras la otra habría sido destruida para evitar su captura tras haberse atascado en una trinchera paraguaya, pero no se sabe con certeza su destino debido a que no existe un informe verificable de su último destino, o un expediente de servicio. Rumores, especialmente de origen paraguayo, hablan de su recuperacion y posterior uso por parte de Bolivia en la defensa de Villamontes. Pero esto no ha sido verificado, puesto que otras fuentes señalan que para esa fecha habrían arribado a Bolivia los primeros ejemplares de la Fiat Ansaldo CV-33 (L3/33).-->

Bolivian experiences and tactics
The use of armoured vehicles in the Chaco were relatively ineffective due to their scant numbers, the lack of presence and employment of doctrine, the harsh climate and bushy terrain of the Chaco and by the logistic difficulties faced by the Bolivian Army. As occurred in Europe in the First World War, and during the inter-war period, many Bolivian officers were not convinced of the potential of the tank, being such a novel vehicle and acquired at the exclusive insistence of General Kundt. It was necessary for time to pass and the Bolivians to gain experience with the use of armoured vehicles.

Back in Germany, Wim Brandt wrote an article about his experiences in the Chaco War on the magazine Beihefte zum Militar-Wochenblatt. He criticized the Vickers design regarding their engine-cooling system, armour, gunsight and tracks; according to Brandt, the only remarkable feature of the 6-ton tanks were the dampers. He advised against firing the tank guns while moving, a guideline that became standard during World War II. Brandt also recommended that all crew members should undertake training as drivers.

The tanks were employed primarily as part of artillery units, almost as self-propelled support pieces, and infantry units were not trained to operate jointly with armoured units. An example of this was the two units captured at Campo Vía, which had been deployed without supporting infantry protection.