The son of an old friend asked to read this series. I posted it here for easier access, and I hope you don’t mind reading, or reading it again. The pictures have been removed, and all the links have been checked. M
Submarine Pens of the Third Reich
I’ve been fascinated by submarines since I was a child. Both my Uncle Charlie and Cousin Tom were in the Submarine Service, and submarines were pointed out to me at every opportunity. As a teen, I was able to visit my cousin’s boat when it was stationed here. In the bay, the flotilla of subs attached to the tender seemed like a mother with her ducklings. When I read about World War Two (WWII) submarine pens, the thick protection for German subs, I began doing a little online research to find out more. At first, nothing answered my top questions. How were they built? And did they prolong the war?
I had not known that after WWI the Treaty of Versailles had limited the number of surface ships Germany could have. Well before the Start of the Second Would War, Germany began a buildup of their undersea fleet. By the late 1930’s, warfare technology had advanced enough so the head of German Naval Command felt a need for far stronger shelters for their U Boat fleet. The failure of the air war against Britain, the 1940 Royal Air Force raid on Berlin, plus the German occupation of France combined to trigger a massive building program of submarine pens.
They called upon the engineers of Organization Todt, (OT), to create structures that would withstand the severest bombing while serving the needs of the submarine fleet. Fritz Todt, an engineer and Hitler’s favorite architect of the time, had founded an engineering business just after WWI. After Hitler came to power, he absorbed the company into the Nazi party structure, and he named the Organization after Todt. This organization was responsible for a huge range of engineering projects both in pre-World War II Germany such as the Autobahn, and in the occupied territories during WWII such as the Westwall…known in English as the Siegfried Line.
Todt told Hitler that he would never win the war, and in February 1942 he died in a still unexplained air crash. Hitler moved Albert Speer, his newly favorite architect, in to head Organization Todt and named him Reich Minister of Armaments and Munitions.
I found the sheer number of trucks and equipment needed to accomplish the goals the Kriegsmarine set overwhelming. OT had taken charge of German private industry and drained it of equipment and workers to build the massive Siegfried Line. By early 1940, Speer requisitioned more equipment and moved it to the Atlantic Coastline to begin building the massive submarine pens the Navy needed. A third of all the concrete mixers in Germany were turned over to OT; 15,000 trucks were assigned ; German railroads made available 6,000, later 10,000, cars a day. Almost 4.4 million cubic metres of concrete was used in the French bunkers alone. I who like facts was left shaking my head over the quantities of everything used.
Six bunkers were finished by the end of the war, and two more were in the planning stages. Four kinds of these massive shelters were constructed. Covered-lock bunkers were built over existing locks to give a U-boat some protection when the lock was emptying or filling. There were construction bunkers used for building new boats. There were also fitting-out bunkers where many U-boats were fitted-out under protection readying them for the sea. Finally, there were shelters for operational boats and repair bunkers which were the most numerous type. The covered lock shelters enabled the boats to come and go at will. Pumping the water out enabled dry dock repairs to be carried out, and some bunkers were even large enough to allow the removal of periscopes and aerials.
Hitler himself took part in the placement of these bunkers. The architects of OT, built models for Hitler to see and approve. In my digging, I discovered that the design specifications for the construction companies involved were created by the Naval Construction Directorate of Hamburg and the OT Einsatzgruppe Hansa from Wilhelmshaven. The association of Agatz & Bock, with offices in Cologne and Berlin, were given the job of the planning and design editing. The Cologne department designed almost all building and construction for the Navy. My mother, an engineer herself, told me that German engineers were thought to be the best in the world at this time.
OT’s expansion needed labor, and most Germans were not drawn to work for low pay in construction. “Some 80% of the OT's members were young non-Germans, many of them volunteers taken in by clever propaganda. But most were forced labour and prisoners-of-war (POW) in positions that were little better than those in the concentration camps.”
Ted Chile writes in his blog, Ted's Excellent Trondheim Adventure, in Norway …“the Dora complex was constructed under the management of the Nazi Todt organization. While not under Albert Speer’s direction, the great “architect” of many of Nazi Germany’s most durable structures, he was the executive who made sure this job was completed in 1943.”
Chile tells us, “Five million 50-pound sacks of German concrete were used to construct Dora. All the concrete and reinforcing steel used in the building came from Germany (as) the Nazis did not trust the quality of local products for use in these structures, and there was always a potential for sabotage of the local materials as well. Modern (for the time) construction techniques were used to complete Dora–wet concrete was pumped to the site to help create walls ranging from 2.5 meters to 10 meters thick within this building. Problems with the integrity of the sea-bed underneath the sub-pen required that it be made to “float” on the bottom of the Trondheim harbor…and, so it does. Slave labor was used extensively on this project…”
An excellent example of the covered lock type bunkers are the locks at Saint-Nazaire. Following the surrender of France to Germany, a heavily fortified U-boat submarine base was built by OT at Saint-Nazaire. With its 9 m (30 ft) thick concrete ceiling, this pen was capable of withstanding almost any bomb in use at the time. The sub base still stands today as its extremely sturdy construction makes demolition uneconomical. The base is now used by cafes, a bar, yacht clubs, and on the roof is an exhibition about Saint-Nazaire.
It was interesting to read that in January of 1943, the Allies implemented incendiary bombing tactics against U-Boat pens along the Atlantic coastline. To cut the number of casualties in Saint-Nazaire, the British Royal Air Force and American aircraft dropped scores of leaflets in the surrounding area before the raids. By the end of the third day, the Allies attacked and burned the entire city to the ground. Casualties were light as most of the civilians had heeded the warning and fled to the safety of the countryside where they were not always welcome. After that, except for the self-contained U-boat base, the city of Saint-Nazaire remained abandoned until the end of the war.
Toward the end of the war, with the increase in allied warship and aircraft escorts, U-boat losses became unacceptable. Many boats were lost, and the earlier "aces" with them. Inexperienced crews lost even more boats in the final days. There were only156 boats to surrender during those last days.
“After D-day and the liberation of most of France in 1944, German troops in Saint-Nazaire's submarine base refused to surrender. They holed up as did their counterparts in the La Rochelle and Lorient bases.” Since the Germans could no longer conduct major submarine operations from the bases without a supply line, General Dwight D. Eisenhower decided to simply go around these three ports, and focus the Allied resources on the invasion of Germany. “Saint-Nazaire and the other two German "pockets" remained under Nazi control until the last day of the war in Europe, 8 May 1945.”
Derick Waller writes in his definitive account of the U Boats that, “UK plans for German naval disarmament were initially formulated in 1942 and 1943, and one of the highest priorities was the objective of ensuring the total elimination of the Kriegsmarine at the end of the war.” All boats were ordered to cease operations and return to Norway in May of 1945 or sail to reception areas. A number of the boats were captured in their coastal pens, and several of them remain there today. U-boat.net
says, “When the base at Saint Nazaire was entered a Type IXC boat U-510 was discovered there, having just returned from the Far East on the 23th April 1945. She was in excellent shape and was commissioned into the French Navy as S-11 Bouan in 1946 and was to remain operational until 1963.”
Today I accessed the records of the submarine pen building program. Like many of the other bunkers, the massive structure at Saint Nazaire is now mostly in private hands. We now know how the 22 bunkers were constructed and if the records were available, we would know who was the designer of them inside the Organization Todt. I was pleased to learn that the pens did not prolong the war. When General Eisenhower moved his troops around the bunkers onward toward Berlin, the men and ships accomplished nothing more. Allies used several of these bunkers to practice their penetration bombing runs totally wiping them away. We are left now with many massive concrete structures to house day sailors and small clubs and memorials built near the death and suffering that built the bunkers.
: bases and more
: images for U boat pens
St Nazaire with good descriptions and some photos
U boats in WWI
pdf file on construction good for small kids
U boat bases
the 30th Flotillia was stationed in the Black Sea at Constanta, Romania with a provisioning facility at Feodosia on the Crimean Peninsula. sub pens in the med
Last updated September 26, 2020