Treaty of Defensive Alliance (Bolivia–Peru) in the context of "Defense pact"

The War of the Pacific (Spanish: Guerra del Pacífico), also known by multiple other names, was a war between Chile and a Bolivian–Peruvian alliance from 1879 to 1884. Fought over Chilean claims on coastal Bolivian territory in the Atacama Desert, the war ended with victory for Chile, which gained a significant amount of resource-rich territory from Peru and Bolivia.

The direct cause of the war was a nitrate taxation dispute between Bolivia and Chile, with Peru being drawn in due to its secret alliance with Bolivia. Some historians have pointed to deeper origins of the war, such as the interest of Chile and Peru in the nitrate business, a long-standing rivalry between Chile and Peru for regional hegemony, as well as the political and economical disparities between the stability of Chile and the volatility of Peru and Bolivia.In February 1878, Bolivia increased taxes on the Chilean mining company Compañía de Salitres y Ferrocarril de Antofagasta [es] (CSFA), in violation of the Boundary Treaty of 1874 which established the border between both countries and prohibited tax increases for mining. Chile protested the violation of the treaty and requested international arbitration, but the Bolivian government, presided by Hilarión Daza, considered this an internal issue subject to the jurisdiction of the Bolivian courts. Chile insisted that the breach of the treaty would mean that the territorial borders denoted in it were no longer settled. Despite this, Hilarión Daza rescinded the license of the Chilean company, seized its assets and put it up for auction. On the day of the auction, 14 February 1879, Chile's armed forces occupied without resistance the Bolivian port city of Antofagasta, which was mostly inhabited by Chilean miners. War was declared between Bolivia and Chile on 1 March 1879, and between Chile and Peru on 5 April 1879.