Early in the conflict, Bordeaux had been chosen by the Italians to station their “Betasom” fleet of submarines (the Greek prefix “Beta” in reference to the “B” of Bordeaux, “som” being short for sommergibili, or submarine in Italian). From the base, Italian submarines participated in the 1940-1943 Battle of the Atlantic as part of the anti-shipping campaign against the Allies. The Germans soon noted the strategic interest of the city’s location, far from the inland front lines and ideally positioned for operations in the Atlantic Ocean.
In the summer of 1941, the decision was taken by one Admiral Dönitz to build a protective bunker in Bordeaux, and construction work began in September of that year. By October 1942 the first German u-boats were stationed there and the base went on to become the home of supply boats, mine-layers, torpedo transports and, above all, the 42-strong 12th Flotilla of very long-range boats. Some of the longest voyages of the war set out from Bordeaux, including a 225-day patrol that was completed in October 1943. After the Italian capitulation in September 1943, five of their submarines were also taken over by the Germans.
The 12th Flotilla was disbanded on 25 August 1944 ahead of the imminent arrival of the Allied forces, who went on to seize the base. Three surviving submarines succeeded in escaping to Germany and Norway and were transferred to other fleets. At the base itself, just two unseaworthy submarines remained. Both were scuttled.
The scale of the structure is mind-boggling. The bunker, which covers a total area of 43,000 square metres, is 245 metres long, 162 metres wide, 19 metres high and much of its roof is a near-indestructible 9.20 metres thick. 600,000 cubic metres of concrete were used to build it.
There are 11 berths in all. Pens 1 to 4 are wet docks, each of which is 20 metres wide and 106 metres long. They could each house two u-boats. Pens 5 to 11 are 14-metre-wide dry dock cales, ranging from 96 to 104 metres in length. Each could house one submarine, the water being removed whenever necessary through the use of powerful pumps.
Construction work on the bunker was only complete in mid 1944. It is estimated that up to 6,000 workers, mainly Spanish and Portuguese prisoners of war, worked relentlessly day and night in merciless conditions. While a popular urban myth suggests that some fell into the depths of the building's foundations where they perished as the concrete slowly set around them (today most authorities do not believe that to be factually correct), it is true that many of the construction workers died in accidents, of exhaustion, or drowned. A solemn memorial has been erected in tribute to those who took part in the construction, and particularly to those who lost their lives.
Today the berths are hauntingly empty shells, occasionally used by amateur yachtsmen when working on their boats. Sections of the building are used for cultural events (drama, exhibitions and concerts) but it seems that the place will never shake off the cumbersome weight of its war-time legacy.
It will however be interesting to monitor the area in the coming years as the city of Bordeaux seeks to re-develop the docklands into an attractive environment to which people will be drawn to work, rest and play. The first landmark project, the highly-awaited Cité du Vin, thus saw the day in 2016.
Much has been written about the u-boat base, but the following are of particular interest: