The Spanish Civil War, fought between the Nationalists and the Republicans from July 1936 to April 1939, is most frequently remembered for its ferocious political divisions and grinding land battles. But there is another crucial but oft-neglected feature of that conflict: the war at sea. Resources, geography and politics combined to make the maritime aspects of the war critically important to both sides. Once it became clear that war would be a long one, both Nationalists and Republicans had to search abroad for resources to continue the struggle. The Republic first turned to France, but French domestic and international politics quickly strangled attempts at assistance. With France ruled out as a source for military supplies, the Soviet Union stepped into the breach. With France having closed the Franco-Spanish border to the shipment of war materials, Soviet supplies had to arrive by ship. The Nationalists had an easier time finding foreign aid, as Hitler and Mussolini acted promptly to meet their needs, but the weapons, munitions and ‘volunteers’ Germany and Italy provided also had to come by sea.

The Spanish navy split at the start of the civil war. Both Nationalists and Republicans had ships and bases; both sides had important tasks for their naval forces. The result was an active maritime war in which the navies carried out a full panoply of missions: trade protection and trade interdiction at the forefront, but also shore bombardments, offensive sweeps, mine warfare and troop transport and landing operations. Moreover, the war at sea was multi-dimensional. Aircraft participated. Submarines prowled. Spanish ships were shelled, bombed, torpedoed and mined. Ships of other nations were targeted as well, often mistakenly but sometimes deliberately. Spanish operations ranged from the North Sea south to the Gulf of Guinea, and from Malta west across the Mediterranean Sea and into the Atlantic Ocean. The two sides fought more than a dozen engagements involving destroyer-sized ships or larger. The Nationalists lost a battleship and a heavy cruiser during the conflict. The Republicans lost a battleship, two destroyers and four submarines, in addition to having other ships heavily damaged.

Foreign navies played a significant role. German and Italian warships protected the troops and supplies sent to the Nationalists. The Kriegsmarine’s reborn submarine arm scored its first kill in December 1936, when U-34 sank the Republican submarine C-3. The Admiral Graf Spee took her first prize, a Republican merchant ship, off the Spanish Mediterranean coast in January 1937. The Regia Marina extended the Nationalist war against trade to the Dardanelles, with Italian submarines and destroyers stalking Republican and Soviet merchant ships as they made their perilous way westward from Black Sea ports. The British and French navies protected neutral shipping in the war zones, at first just those flying their own nations’ ensigns, but later as part of an international effort. ASDIC underwater detection gear was first used in combat in 1937 when the British destroyer Havock used it to hunt the Italian submarine Iride after the Italian boat had attacked the Royal Navy ship.

The Fleet that Fought Itself chronicles the Spanish Civil War at sea from the initial struggles to secure ships and bases to the eventual internment of the Republican fleet in French North Africa. More than providing a chronology of events, the book examines the operational effectiveness of both Spanish navies while also assessing the impact that foreign navies had on the war at sea. In examining the Republican navy, the book offers a corrective to the usual narrative characterizing that navy as inert. Operations are discussed in detail, including the attempts by the Republican navy to keep the Nationalists from transferring troops from Spanish Morocco to mainland Spain, Nationalist attempts to sever Republican trade links in the Mediterranean and along the northern Spanish coast, and offensive sweeps by both forces. The book traces the influence of air power on the naval war, with both warships and merchant shipping being attacked at sea and in harbor. Invasion attempts also appear: for the Republicans, a landing on Majorca, for the Nationalists, an attempt to seize the Republican naval base at Cartagena by coup de main. Activities of foreign navies include the first war patrols of German submarines, the massive effort mounted by the Regia Marina to block Soviet aid from the Black Sea, and British and French efforts to protect trade under their flags and eventually all neutral trade from Nationalist, German and Italian depredations.

The Spanish Civil War at sea was rich in anecdote and incident, even though relatively unknown to English-speaking readers. The Fleet that Fought Itself aims to fill this gap and to spark further interest in this fascinating dimension of that long and bitter conflict.

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