Despite increasing border tensions since the 1840s, both countries fought together against Spain in the Chincha Islands War (1864–65) and resolved the question under the Governments of Mariano Melgarejo in Bolivia and José Joaquín Pérez in Chile. But before long, both countries were discontented with it, and Peru and Bolivia signed a secret treaty against Chile in 1873. The Lindsay-Corral protocol, thought to clarify the treaty, was approved by Chile but never by Bolivia.