The Battle of Cape Palos, also known as the Second Battle of Cape Palos, was a biggest naval battle of the Spanish Civil War, fought on the night of March 5 - 6 1938, 70 miles East off Cape Palos near Cartagena.

During the Spanish Civil War 1936-1939, about half of the Spanish Navy was seized by the Republican government and the other half by Franco's Nationalists. Government forces had more destroyers, but Franco seized both newest heavy cruisers Canarias and Baleares, armed with eight 203 mm (8 in) guns each. From the beginning of the war there were several encounters of both sides' ships, but without major losses.

On March 5, 1938, both Nationalist heavy cruisers and a light cruiser Almirante Cervera with 3 destroyers sailed off Palma de Mallorca naval base, in a distant cover of a ship convoy from Italy with war equipment. On the same day, the Republican main forces, consisting of 2 light cruisers: modern Libertad and older Méndez Núñez and 5 destroyers, sailed from Cartagena. At night, Nationalist destroyers returned to base, while cruisers remained.

Both forces, going in opposite directions, met on 0:40 at night. One of Republican destroyers fired torpedoes, but missed, and both fleets passed themselves. Nationalist Rear Admiral de Vierna wanted to wait until dawn, that would enable him to use superior artillery of his ships, but the Republican Vice Admiral de Ubieto decided to turn and pursuit the enemy.

Both fleets encountered again about 2:15. Nationalist cruisers opened fire to Libertad, from about 5 km distance, and Republican cruisers answered with fire. However, due to lack of experience in night combat, the artillery fire was not efficient. At that time, Nationalist cruisers found themselves between a line of Republican cruisers, and a line of 3 destroyers, which they probably didn't notice, being engaged with cruisers. As a result, Republican destroyers: Sanchéz Barcáiztegui, Lepanto and Almirante Antequera came closer, at about 3 km distance, and fired 12 torpedoes. About 2:20, two or three torpedoes, probably from Lepanto, hit Baleares, causing a big explosion. Two survivng Nationalist cruisers quickly sailed out, while Baleares sunk after a few hours. Out of 765 crewmen, 372 were saved, mostly by British ships. Admiral de Vierna was killed in a battle.

This was the biggest naval battle of the Spanish Civil War and the biggest Republican victory, but it did not affect land combat, that was not succesfull for Republicans.