War of the Pacific

Between 1879 and 1884, Chile fought Peru and Bolivia in the War of the Pacific, a conflict over the nitrate- and mineral-rich desert along South America's western coast. Chile's victory reshaped the continent's map: Bolivia lost its entire coastline and became landlocked, Peru lost its southern province of Tarapacá, and Chile emerged as the leading military power on the Pacific coast. The loss of the coast remains a live issue in Bolivian politics and diplomacy today.

The roots of the war lay in the Atacama Desert, a sparsely populated region whose borders had long been vaguely defined. In the mid-nineteenth century, deposits of guano and sodium nitrate, both valuable as fertilizer and in explosives, turned the area into an economic prize. Chilean capital and workers, often backed by British investment, moved into Bolivian territory and dominated the mining towns. Treaties in 1866 and 1874 set the Chile-Bolivia boundary and limited taxes on Chilean businesses, but Bolivia's government later imposed a new tax on a Chilean-British nitrate company at Antofagasta. Chile saw this as a treaty violation. Peru, meanwhile, had a secret defensive alliance with Bolivia signed in 1873, and it had its own nationalized nitrate industry in Tarapacá.

In February 1879, Chilean forces occupied the Bolivian port of Antofagasta, and war was declared in April after Peru refused to remain neutral. Control of the sea was decisive because the desert made overland supply extremely difficult. After the naval clash at Iquique and the capture of the Peruvian ironclad Huáscar at Angamos in October 1879, Chile held command of the coast. Its armies then took Tarapacá, advanced on Tacna and Arica, and by January 1881 had occupied Lima. Bolivia largely withdrew from the fighting after 1880.

Peru's resistance did not end with the fall of its capital. A guerrilla campaign in the Andes continued for some time, though the country was devastated and politically divided. The Treaty of Ancón in 1883 ended the war with Peru, ceding Tarapacá to Chile and arranging for Tacna and Arica to remain under Chilean control pending a later decision. Bolivia signed a truce in 1884, and a formal treaty in 1904 confirmed Chile's possession of the former Bolivian coast in exchange for a railway and financial compensation.

The consequences lasted well beyond the fighting. Nitrate revenues enriched the Chilean state for decades, until synthetic fertilizers undermined the industry in the twentieth century. Tacna returned to Peru in 1929, while Arica stayed with Chile. Bolivia has continued to seek sovereign access to the Pacific, and it brought the issue before the International Court of Justice, which in 2018 ruled that Chile had no obligation to negotiate such access.