Bombing German Submarine Pens:
October 1942-April 1945

The AAF's strategic bombardment of enemy ports and harbors also contributed to the destruction of the German U-boat fleet, although such operations were not part of the official Antisubmarine Command. From October 1942 through July 1943, U.S. strategic forces bombed German submarine pens in France with little effect. From March 1944 to April 1945, they proved far more successful in destroying U-boats anchored in harbors on the Mediterranean, North, and Baltic Seas.

After the fall of France in 1940, Germany built facilities at five ports--Brest, Lorient, St. Nazaire, La Pallice (or La Rochelle), and Bordeaux--to accommodate its submarine fleet. U-boats returning to port were serviced within bombproof concrete pens. The surrounding towns provided workers, hotels, and recreation for the crews. Until the Allied landing on the continent in 1944, those facilities berthed most of the U-boat fleet.

In early 1942, when the Allies gave top priority to the war against the German submarines, they targeted the submarine manufacturing plants in Germany and the submarine pens in France for strategic bombardment. A successful intensive bombing effort would decrease the production rate for submarines, reduce the number of U-boats at sea, and disrupt the refitting of operational submarines. In a directive issued on October 20, the Allied commander-in-chief, Gen. Dwight D. Eisenhower, gave the submarine pens and production facilites first and second priority, respectively. Over the next ten months, the Eighth Air Force, the AAF's strategic bombing organization in Great Britain, concentrated on bombing submarine bases in France.

Ninety bombers--B-17s and B-24s--attacked the U-boat base at Lorient on October 21. Because of bad weather, only fifteen aircraft managed to drop thirty high-explosive, one-ton bombs. Five bombs reportedly hit the submarine pen, but failed to penetrate its reinforced concrete. The rest fell in the general area, damaging two submarines not in the pen and destroying several buildings, docks, and other facilities. The raid inflicted  about 150 civilian casualties, mostly among German workers. The AAF bombers encountered very little antiaircraft fire, but lost three aircraft to enemy fighters.

The Lorient mission foreshadowed the difficulties that the Eighth Air Force would have in attacking submarine pens. Protecting not only the submarines but most necessary repair and maintenance facilities, the pens were virtually impervious to all but the heaviest bombs. Destroying nearby structures had little effect on the enemy's ability to

refit operational submarines. Unfortunately, the AAF raids caused only some temporary dislocations and harassed the enemy by destroying auxiliary facilities and neighboring railway yards. Even the final AAF raid by 158 heavy bombers against the St. Nazaire submarine pens on June 28, 1943, failed to yield significant results. U-boat operation continued from the French ports as Allied forces overran France. Four months after D-Day, on September 23, 1944, the last U-boat sailed from St. Nazaire and marked the end of German operations from protected submarine pens.

It was a different story, however, when the U-boats sought refuge in ports with no concrete pens. AAF heavy bombers found them easy prey, particularly in the Mediterranean, North, or Baltic Seas. On March 11, 1944, the AAF destroyed two German submarines in the harbor of Toulon, France, on the Mediterranean.   The bombers returned to Toulon on April 28, July 5, and August 6, and wrecked six

U-boats. A raid on Salamis, Cyprus, on September 24, resulted in two more kills. With the last enemy submarine destroyed in the Mediterranean, the Eighth Air Force found good hunting in German ports on the North and Baltic Seas. In December 1944 and January 1945, the AAF bombers destroyed six U-boats at Hamburg on the North Sea. In the next two months, they destroyed five more at Hamburg, six at Bremen, and three at Wilhelmshaven, all on the North Sea. During April, AAF bombers destroyed eight at Kiel on the Baltic Sea, and three more at Hamburg. In all, the strategic bombing missions claimed forty-one German submarines.