On 21 July, a neutral arbitration commission awarded Paraguay rather than Bolivia the greater part of the disputed Chaco Boreal. The commission's action finally ended the Chaco War [1932-35], itself the culmination of nearly a century of diplomatic and military tensions.

This article outlines that century of dispute in three parts, with the last devoted exclusively to the war itself, part 1 examines the pre-war period to December 1928, while parts 2 and 3 will deal with 1928-32 and 1932-35, respectively. Each includes a description of Bolivian and Paraguayan military campaigns, their forces, and their equipment. Part 4 completes our coverage by providing maps of the area, disposition of forces, and drawings of uniforms.

Ownership of the Chaco, a remote and sparsely settled territory lying between Bolivia and Paraguay, had been in dispute since the mid-19th Century. Early diplomatic discussions, beginning in 1879, failed to settle the question and as a result both sides resorted to force to substantiate their claims. In 1887, Paraguayan forces captured Puerto Pacheco on the upper Paraguay River. In 1913, Bolivian forces clashed with Paraguayan settlers on the lower Pilcomayo River.

Beginning in the early 1920's, both sides tried to establish territorial claims to the area through deliberate exploration, the building of numerous "fortines" [1] and an extensive expansion and modernization of their armed forces under the aegis of foreign military missions.

In Bolivia, Hans Kundt, ex-First World War German General and Bolivian Chief of Staff from 1921-1926, instituted tactical concepts, and spearheaded purchases of new equipment. Paraguay's French military mission [1926-29] pursued similar goals.

Military expansion was dramatic. In 1925-26, Bolivia purchased 15 Breguet Bre 19A2 light bombers and 5 Fokker C.VC reconnaissance aircraft. In 1927, a much publicized Vickers contract included 64 artillery [75 mm and 105 mm], anti-aircraft weapons, 39,000 7.65mm Mauser rifles, 750 7.65mm machine guns, 6 Vickers 143 fighters, 6 Vespa III light bombers, and 2 Vickers 6 ton tanks and 3 Vickers-Carden Lloyd Mk.VIb tankettes; at the same time, add to this order the 12 Curtiss-Wright Falcons and 4 Hawk 1AS acquired from the U.S. [2].

Despite financial restrictions, that same year, Paraguay managed to purchase, in complete secrecy, 7 Wibault Type 73 fighter aircraft and 7 Potez 25 light bombers, 10,000 7.65mm Mauser rifles, 176 7.65mm Madsen light machine guns, 24 75mm and 8 105mm Schneider mountain guns, and two river gunboats [3].

Neither country recieved the bulk of it's purchases until after 1928. By the end of 1928, Bolivia's forces totalled 8,600, in six weak divisions, including 1 Division of approximately 1200 soldiers which garrisoned the Chaco. Paraguay's forces totaled 2,900 in 4 Regiments; at Fahia Negra, Concepcion, Asuncion and Paraguari [cavalry]. A single infantry Battalion and some smaller units were spread out over the Chaco.

The explorations, military expansion and numbers of soldiers in the Chaco increased the possibility of war. In April 1927, a small Paraguayan unit was captured in the vicinity of the upper Paraguay River area. Neutral arbitration helped calm the situation. On 5 December 1928, a more serious incident occurred.