War of the Pacific

The War of the Pacific was fought from 1879 to 1884 between Chile and an alliance of Peru and Bolivia. Sparked by a dispute over taxes on nitrate mining in the Atacama Desert, it ended in a Chilean victory that gave Chile the mineral-rich coastal provinces of both its opponents and left Bolivia without a coastline.

The arid coast where the three countries met held vast deposits of guano and sodium nitrate, prized in the nineteenth century as fertiliser and for making explosives. Much of the mining in Bolivia's coastal province was run by Chilean companies and workers. A boundary treaty of 1874 fixed the Chile–Bolivia border and barred Bolivia from raising taxes on Chilean mining firms there, while Peru, struggling with debt and declining guano revenue, had nationalised the nitrate works in its own province of Tarapacá. Peru and Bolivia had also signed a secret defensive alliance in 1873. Historians point to deeper causes as well, including rivalry between Chile and Peru for leadership on the Pacific coast.

In February 1878 the Bolivian government of Hilarión Daza imposed a new tax on the Chilean-owned Antofagasta Nitrate and Railway Company. Chile argued that this broke the 1874 treaty and asked for arbitration; Bolivia treated it as an internal matter, cancelled the company's licence and ordered its property auctioned. On 14 February 1879, the day of the auction, Chilean troops occupied the port of Antofagasta without resistance. Bolivia declared war on 1 March, and Chile declared war on Peru on 5 April.

Control of the sea was vital, since armies could only be supplied across the desert by ship. At Iquique on 21 May 1879 the Peruvian ironclad Huáscar sank the Chilean Esmeralda, but Peru lost its ironclad Independencia, which ran aground the same day. Though outnumbered, the Huáscar held off the Chilean navy for months until it was captured at the Battle of Angamos on 8 October 1879. With naval supremacy, Chile could carry its armies north.

Chilean forces landed at Pisagua in November 1879 and took Tarapacá, including the port of Iquique, and won the Battle of Tacna on 26 May 1880, after which Bolivia effectively withdrew from the fighting. Peru, under Nicolás de Piérola, refused to make peace. Chile landed an army south of Lima and, after the battles of Chorrillos and Miraflores in January 1881, occupied the Peruvian capital. Peruvian forces under Andrés Avelino Cáceres fought on in the Andes, but were defeated at Huamachuco on 10 July 1883.

The war brought suffering beyond the battlefield. At the outset Peru and Bolivia expelled some 30,000 Chilean residents, both sides accused the other of killing wounded soldiers, and in occupied Peru there was widespread unrest, including deadly attacks on Chinese immigrants, whom some Peruvians accused of supporting Chile. Chile's dead are estimated at about 2,400 to 2,800, with Peruvian and Bolivian losses considerably higher.

The Treaty of Ancón of 20 October 1883 ceded Tarapacá to Chile and gave it temporary control of Tacna and Arica. Bolivia agreed a truce in 1884, and a 1904 treaty confirmed the loss of its coastal department in exchange for railway links and duty-free use of Chilean ports. The Tacna and Arica question was settled only in 1929, when Tacna returned to Peru and Arica stayed Chilean.

Nitrate taxes swelled Chile's treasury, and the country became the leading military power on the Pacific coast of South America. In Peru, the defeat and occupation brought years of instability. In Bolivia, the loss of the sea remains a deeply felt national issue; in 2018 the International Court of Justice rejected Bolivia's arguments in a case brought against Chile.

Our 1878 map shows the borders on the eve of the war, with Bolivia still holding a stretch of Pacific coast between Chile and Peru's province of Tarapacá. Our 1900 map shows the result: Chile reaching north to Tacna, and Bolivia cut off from the sea.