After the Battle of Tacna, and the subsequent retreat of North Peruvian and Bolivian forces, as well as the inminent collapse of the Peru-Bolivia Confederation, the occupation by the Chilean forces officially begins, as well as a process of Chileanization, and in 1911, it is officially incorporated into the Chilean Province of Tacna as the Department of Tarata, with Tarata becoming the commune of the homonymous Department. In 1921, however, Chile abolished the department, and in 1925 gave back the city to Peru under the mediation of U.S. President Calvin Coolidge, who enforced the limits agreed upon on the north, which did not include the city.