William Denny and Brothers built the Antonio Lopez at their Dumbarton shipyard on Scotland's River Clyde, launching her on November 8, 1881, and completing her the following year. She was a working merchant steamship - single screw, driven by a two-cylinder compound steam engine rated at 634 nominal horsepower. The Compania Transatlantica Espanola named her after the company's founder, Antonio Lopez y Lopez, and registered her at Barcelona. For sixteen years she plied Atlantic trade routes, an unremarkable vessel in a large merchant fleet. Nothing in her design or service history suggested she would become a footnote in a war, let alone a National Historic Landmark.

By June 1898, the Spanish-American War had transformed the Caribbean into a theater of naval operations. American warships patrolled the approaches to Puerto Rico, intercepting supply vessels bound for the island's Spanish garrison. The Antonio Lopez sailed from Cadiz carrying military supplies essential to the defense. On June 30, two U.S. cruisers engaged a Spanish squadron that included a cruiser, two gunboats, and the merchant vessel. An American warship pursued and shelled the Antonio Lopez. Outgunned and unable to escape, she ran aground at Ensenada Honda, her hull battered by naval fire, her mission technically complete - the cargo was at Puerto Rico, even if the ship was wrecked getting it there.

Captain Acha Caamano had followed his orders to the letter. Now came the practical work of recovering what the ship had carried. His salvage crews moved quickly, retrieving nearly the entire cargo from the grounded, burning vessel. Only minor articles and a single cannon - lost overboard during the salvage operation - were not recovered. The company's gamble had paid off in material terms: the supplies reached Spanish forces. But the larger gamble was already lost. Within weeks, American forces would land at Guanica on Puerto Rico's southern coast. By August, Spain would sue for peace. The Treaty of Paris in December transferred Puerto Rico, along with Cuba, Guam, and the Philippines, to American control. The Antonio Lopez's desperate run had delivered supplies to an army that was about to surrender the island.

The Antonio Lopez's wreck site lies in approximately 1,700 feet of water off Dorado, Puerto Rico. In 1997, the site was designated a National Historic Landmark - recognition of its singular status as the only known Spanish shipwreck in U.S. waters from the Spanish-American War. The war itself lasted just ten weeks, but it redrew the map of empire, ending Spain's 400-year presence in the Americas and establishing the United States as a colonial power in the Caribbean and Pacific. Beneath the surface off Puerto Rico's north coast, the remains of a Scottish-built steamship carrying Spanish supplies to a Spanish garrison on an island about to become American territory captures the tangled colonial history of the Caribbean in a single wreck.