Tacna Department (Chile)

Tacna (Spanish pronunciation: [ˈtaɣna]; Aymara and Quechua: Taqna) was a department of Tacna, a province of Chile. Located in the Atacama Desert, it existed between 1884 and 1929. Prior to its formal establishment, its area had already been de facto administered by the Chilean Army since 1880, following an eight month military campaign that took place during the War of the Pacific. Its capital was the city of Tacna.

The Treaty of Ancón, which put an end to the war, was signed on October 20, 1883. The following year, the province was formally created on October 31, incorporating the former Peruvian provinces of Tacna, Arica and Tarata, the latter of which would be constested due to differing interpretations of the course of the Sama River, the province's provisional northern border. Under the treaty, the territory would be administered by Chile for a ten-year period, after which a plebiscite would determine its fate. Originally meant to be held in 1894, was ultimately not carried out.

The dispute regarding Tacna and Arica continued into 1929, during which relations soured following the local acculturation policy of the Chilean government and the active campaigning by Peruvian locals. The dispute ended through the signing of the Treaty of Lima, under which Tacna would be returned to Peru, while Arica would be formally incorporated into Chile. The handover of Tacna took place at midnight on August 28, 1929, marking the end of the Chilean administration.