For some years Chilean companies and speculators, aided by foreign capital mainly British in origin, had been working deposits of nitrate of soda in the province of Antofagasta, or "the desert of Atacama," a region along the coast to the northward belonging to Bolivia, and also in the provinces of Tacna, Arica, and Tarapaca, still farther to the northward, belonging to Peru.

Because boundary lines were not altogether clear and because the three countries were all eager to exploit these deposits, controversies over this debatable ground were sure to rise.

For the privilege of developing portions of this region, individuals and companies had obtained concessions from the various governments concerned; elsewhere, industrial free lances dug away without reference to such formalities.
It is quite likely that Chile, whose motto was "By Right or by Might," was prepared to sustain the claims of its citizens by either alternative.

At all events, scenting a prospective conflict, Chile had devoted much attention to the development of its naval and military establishment--a state of affairs which did not escape the observation of its suspicious neighbors.
The policy of Peru was determined partly by personal motives and partly by reasons of state.

In 1873 the President, lacking sufficient financial and political support to keep himself in office, resolved upon the risky expedient of arousing popular passion against Chile, in the hope that he might thereby replenish the national treasury.