-Chile and US get into a fight circa 1883
-Chile wins hands down and raids SF mint, carrying off large amounts of gold and putting the fear of the Almighty in DC. Maybe they take a few islands off the coast of California as 'coaling stations' and/or US property in Hawaii as an extra humiliation
-US looks to modernize their fleet and fast, but until 1898 are very inactive in the Pacific as well as Atlantic. Chile uses its newfound glory to become lead Spanish nation in South America with British support while Argentina groes closer to Germany.
-US and Spain play out war akin to OTL Spanish-American war, Chile stays well clear of the Anglo giant and sells both the Hawaiian interests and Californian islands back to the US for reasonable prices.
-US develops torpedoes and submarines well ahead of the curve and becomes an even greater power than OTL with WW1 made less destructive and WW2 shortened by 4-6 months
-Chile gets mauled without apology during Pinochet takeover and Anglos exact revenge in an almost, 'Nothing Lasts Forever' style.