Battle of Abtao: Spanish squadron versus combined Peruvian-Chilean fleet

Background. The conflict arose from Spain's seizure of the guano-rich Chincha Islands on April 14, 1864, in retaliation for Peru's refusal to pay an indemnity. Chile and Peru formally signed an alliance against Spain on December 5, 1865. On January 16, 1866, the combined fleet, including the captured schooner Covadonga, convoyed from Ancud to Abtao Island, where the Chileans built fortifications in a shallow channel.

Engagement. Spanish commander Casto Méndez Núñez ordered frigates Villa de Madrid and Reina Blanca to intercept the enemy fleet. The Spanish squadron appeared off Abtao on February 7, 1866, but avoided entering the shallow waters. The allied ships, anchored behind the island, were protected by these shallows, leading to a long-range exchange of fire.

Outcome. The battle resulted in a long-range exchange in which Spanish gunnery proved more accurate, inflicting damage on the Chilean and Peruvian ships. The Spanish ships had arrived off the island on February 4, 1866, without being detected by the enemy. The engagement was limited by the inability of the Spanish vessels to navigate the shallow waters near the island.