 Complete the following phrase:  Conflicting Argentine and Chilean claims to Patagonia, the southernmost region in South America, had been causing tension between the two countries since the 1840s. Both countries were incapable of enforcing these claims with a seaborne force, though: in 1860, the Chileans had only five small vessels, while the Argentine Navy had no seagoing ships. These attitudes quickly changed when the circumstances warranted; when Chile joined Peru against Spain in the 