In March 1866—more than 30 years before the Spanish-American War—the United States and the Spanish Empire came perilously close to a naval clash of arms off the thriving Chilean port city of Valparaiso. Since the enunciation of the Monroe Doctrine in 1823, the possibility of such a showdown had been imminent in the waters of the Western Hemisphere.
The possibility became more of a probability as a Spanish task force, headed by Admiral Casto Méndez Núñez and boasting the formidable armored frigate Numancia in the vanguard, began bombarding undefended port towns in a mid-century Spanish attempt at power projection. Spain’s assertiveness had forced an unintended result, galvanizing a military alliance between Chile, Peru, Ecuador, and Bolivia. And as Admiral Núñez set his sights on Valparaiso, it became clear that to attack the city would entail serious international ramifications, thanks to the presence there of French, British, and American citizens and property.