thumb|300px|Illustration of the dreadnought in 1912
In the latter half of the 19th century, the Spanish Navy had built a series of ironclad warships that culminated in the barbette ship Pelayo in the 1880s. Following the destruction of much of the Spanish fleet in the Spanish–American War in 1898, Spain slowly began to rebuild its navy. In the early 20th century, the Spanish Navy built three battleships and planned several more; the three ships that were completed were the vessels of the . These ships were the smallest dreadnought-type battleships ever built. A further three ships of the were authorized by the Navy Law of 1913, but the outbreak of World War I prevented these ships from being built, as Spain was heavily dependent on Great Britain for material and technical expertise. The three completed battleships all served in the Rif War in North Africa, where the lead ship, España, ran aground and was wrecked.
Following the end of the First World War, occasional plans for the construction of new battleships were proposed, including a small design deriving from Britain's powerful s. However, nothing had come of these efforts by the time of the outbreak of the Spanish Civil War. Following the victory of Francisco Franco's Nationalists in that conflict, in which both of the surviving Spanish battleships—one serving on the side of the Nationalists, the other on that of the Republicans—had been destroyed, proposals for the construction of four fast battleships to an Italian design, as well as the construction of "large cruisers"—the only battlecruiser designs proposed for or by Spain—were made. However, the outbreak of the Second World War resulted in these plans being disrupted.
España class
thumb|right|España (ex-Alfonso XIII) as she appeared in 1937
Authorized under the Navy Law of 1908 and assigned to the Primera Escuadra (First Squadron), the España class were the first and only Spanish dreadnoughts, and also the smallest of that type of ship ever to be built. Considered by some to be more "Dreadnought-type coast-defense ships" than pure battleships, In the mid-1930s, it was proposed that the two surviving ships of the class be rebuilt as "pocket battleships", including a lengthening of the hull and rearranging of the turrets to a centerline alignment. By 1936, a more modest rebuild was proposed, including conversion to oil firing, but the outbreak of the Spanish Civil War put this plan to rest.
The remaining two ships of the class, one operating on each side, were both lost in the Spanish Civil War. España (ex-Alfonso XIII), serving the Nationalist side, struck a mine in April 1937 and sunk, while Jaime I fighting as part of the Republican navy, suffered an internal explosion at Cartagena in June 1937, being scuttled as a precautionary measure afterwards. The wreck was raised the following year before being scrapped in 1939.
! scope="col" rowspan="2" | Armament
A "super-Treaty cruiser" type was also projected as part of Franco's naval expansion plans, with some designs proposed for the type calling for an armament of six guns; alternatively, some have speculated that the Spanish desired to purchase the two triple turrets that were available following the decision by the German Kriegsmarine to rebuild the damaged battleship with twin turrets. The war situation meant that nothing was to come of this project either.
See also
- List of battleships
- List of retired Spanish Navy ships
- List of galleons of Spain
- List of ships of the line of Spain