TACNA, a northern province of Chile, in dispute with Peru from 1893 onwards, bounded N. by Peru, E. by Bolivia, S. by Tarapaca, and W. by the Pacific. Area, 9251 sq. m. Pop. (1895) 24,160. It belongs to the desert region of the Pacific coast, and is valuable because of its deposits of nitrate of soda and some undeveloped mineral resources. There are a few fertile spots near the mountains, where mountain streams afford irrigation and potable water, and support small populations, but in general Tacna is occupied for mining purposes only. None of its streams crosses the entire width of the province; they are all lost in its desert sands. The climate is hot, and earthquakes are frequent and sometimes violent. There is one railway in the province, running from the city of Tacna to Arica (q.v.), and in 1910 another from Arica to La Paz, Bolivia, was under construction by the Chilean government. The province consists of two departments, Tacna and Arica, which once formed part of the Peruvian department of Moquegua. Its capital is Tacna (pop. 1895, 9418; 1902, estimated 11,504), a small inland town 48 m. by rail from Arica, in a fertile valley among the foothills of the Andes. Existence is made possible in this oasis by a small mountain stream, also called Tacna, which supports a scanty vegetation. The town owes its existence to the Bolivian trade from La Paz and Oruro, and is the residence of a number of foreign merchants. Tacna was captured by a Chilean force under General Baquedano on the 27th of May 1880.
At the close of the war between Chile and Peru (1879–1883), the terms of the treaty of Ancon (signed by representatives of the two countries on the 20th of October 1883) were practically dictated by Chile, and by one of the provisions the Peruvian provinces of Tacna and Arica were to be occupied and exploited by Chile for a period of ten years, when a plebiscite should be taken of their inhabitants to determine whether they would remain with Chile or return to Peru, the country acquiring the two provinces in this manner to pay the other $10,000,000. At the termination of the period Peru wished the plebiscite to be left to the original population, while Chile wanted it to include the large number of Chilean labourers sent into the province. Chile refused to submit the dispute to arbitration, and it remained unsettled. Meanwhile Chile expelled the Peruvian priests, and treated the province more like a conquered territory than a temporary pledge.