They were built in Spain by the Vickers-Armstrongs subsidiary Sociedad Española de Construcción Naval upon a British design, and were a modified version of the Royal Navy′s County class.

The Spanish ships had a stronger secondary armament and although the original design included a catapult for a seaplane this was never installed.

Both ships were making their final sea trials when seized by the Nationalist side in the Spanish Civil War.

Canarias was the flagship of the Nationalist Navy and sank 34 ships including the Republican destroyer Almirante Ferrándiz and the Soviet merchant Komsomol.

The stern half remained afloat and 372 of her crew of 1221 were saved by British destroyers Boreas and Kempenfelt.