The War of the Pacific, spanning from 1879 to 1884, was a significant conflict in South American history, involving Chile on one side and the allied forces of Bolivia and Peru on the other. This war, primarily centered around the control of the Atacama Desert, a region rich in nitrate deposits, concluded with a truce in 1884, but it was not until 1904 that a definitive treaty was signed, reshaping the geopolitical landscape of the region.

The origins of the War of the Pacific can be traced back to economic interests and territorial disputes. The Atacama Desert, lying between Chile and Bolivia, was coveted for its nitrate deposits, which had a high global demand due to their use in fertilizers and explosives. A crucial point of contention arose when Bolivia imposed taxes on Chilean companies operating in the region, breaching an agreement from 1874 which exempted Chilean businesses from such taxes for 25 years. This action, compounded by the already existing ambiguity over territorial boundaries in the resource-rich area, set the stage for the conflict.

As the war unfolded, Chile emerged as a formidable military force, achieving significant victories and capturing key port cities of Peru and Bolivia. The naval aspect of the conflict played a crucial role, with Chile eventually dominating the sea routes, a strategic advantage that enabled them to land troops along various coastal areas.

The end of hostilities in 1884 led to a period of negotiation and political maneuvering, culminating in the Treaty of Peace and Friendship signed in 1904 between Chile and Bolivia. This treaty, more than just a formal end to the war, represented a significant territorial rearrangement. Chile gained permanent control over the disputed Atacama region, which led to Bolivia losing its access to the sea, effectively becoming a landlocked country. This loss has since been a source of national trauma for Bolivia and a persistent issue in its foreign relations.

Moreover, the 1904 treaty included several provisions aimed at mitigating Bolivia's loss. Chile agreed to construct a railroad connecting the Bolivian capital, La Paz, with the Chilean port of Arica, and guaranteed Bolivia commercial transit rights through the ports now under Chilean control. Despite these provisions, the treaty's ramifications have been long-lasting, influencing the diplomatic relations between Bolivia and Chile for over a century. Bolivia's quest for a sovereign access to the sea has remained a contentious and unresolved issue, underscoring the enduring impact of the War of the Pacific and the 1904 treaty in the geopolitical dynamics of South America.