Peru and Chile sign the Treaty of Ancón, by which the Tarapacá province is ceded to the latter, bringing an end to Peru’s involvement in the War of the Pacific.

The Treaty of Ancón, signed on October 20, 1883, officially ended the War of the Pacific between Peru and Chile. This war, which had begun in 1879, was primarily fought over control of the nitrate-rich territories in the Atacama Desert. The treaty was signed in the town of Ancón, near Lima, and came after years of devastating conflict that left Peru economically weakened and politically unstable. The negotiations were influenced heavily by Chile’s military occupation of Lima, which gave Chile a strong advantage in dictating the terms of peace.

Under the treaty, Peru ceded the province of Tarapacá to Chile permanently. This was a significant territorial loss, as Tarapacá was one of Peru’s most resource-rich regions, especially valuable for its nitrates, which were crucial to the global fertilizer and explosives industries of the time. Additionally, the provinces of Tacna and Arica were to remain under Chilean administration for ten years, after which a plebiscite would determine their final sovereignty. However, this plebiscite was delayed for decades, causing long-standing diplomatic tensions between the two nations that were not fully resolved until the Treaty of Lima in 1929.

The Treaty of Ancón marked a turning point in South American geopolitics. For Chile, it secured economic prosperity through access to the nitrate fields, propelling its economy forward in the late 19th and early 20th centuries. For Peru, however, it represented a period of national humiliation and loss that deeply affected its sense of sovereignty and national identity. The treaty also reshaped regional power dynamics, elevating Chile as a dominant Pacific power while compelling Peru to rebuild its institutions and economy in the aftermath of war.