This immense complex, built during WW11 to house the 'Grey Wolves' of the  6th and 7th U-Flotillas, dominates the harbour of 21st-century St-Nazaire, just as it did the battle area of more than sixty years ago. Capable of accommodating 20 U-Boats, it took the form of 14 deep chambers, some of which could be drained and used as dry docks for even the most complex repairs. Accounting for almost 500,000 cubic metres of heavily reinforced concrete, its massive walls and roof, armoured doors, gun platforms and firing embrasures, combined to make it a self-contained fortress within which boats could be received, repaired, refuelled and dispatched almost without reference to the war being pursued beyond its confines. Heavily bombed over a period of several years by both British and American aircraft, it was never penetrated, nor was any damage ever caused to its boats or personnel.

Some idea of scale can be gained from the figures atop the pedestrian promenade which runs along the eastern edge of the roof above a covered firing gallery. At the time of 'Chariot', German riflemen  and machine-gunners on top of this massive slab had an unobstructed field of fire over much of the Commando target area, part of which (the Old Entrance) is shown, right, in a photograph taken from a flak position high on the Pen complex roof.

The images below show the rear of the pens stretching northwards along the Boulevard de la Légion d'Honneur, and the echoing interior of one of the 14 massive chambers. Currently being redeveloped, these house the main Tourism Office, a shop and café/bar in addition to Escal' Atlantic, a permanent exhibition dedicated to the port's long history of constructing ocean liners. Ongoing work in the area of the pens shown below left has added a geodetic dome to the roof and ultimately will transform the southernmost chambers into entertainment and commercial venues.


On accessing the roof, the northernmost portion is set apart by its amazing complex of massive, interlocking concrete beams and struts (shown below), specifically designed to break up Allied bombs even before they could impact on the main roof slabs. This portion was the only part to be completed fully before the end of the war.


As shown in the above interior plan, a service railway ran through the full length of the complex, protected by thick armoured doors at each end. This shot, looking south, shows the path of the railway along only a small portion of its length and gives some idea of the sheer scale of the structure. To the left are the main chambers within which U-Boats would have been docked for service and repair: while to the right is the location of the supporting services - stores, offices, workshops, etc, housed on multiple levels.

The ultra-modern lighting array betrays the fact that these are the pens currently under development - a massive task as it involves breaking through walls several feet thick and heavily reinforced with rebar.

The 'Das Boot' connection

In the movie 'Das Boot', a young propaganda photographer arrives at a U-Boat base to join the crew of a boat - whose captain was played by Jürgen Prochnow - and share with them the trials of a war patrol. In real life the photographer was called Lothar-Günther Buchheim, and he arrived here, in St-Nazaire, October 1941, to join U-96, a boat belonging to the 7th Flotilla (Wegener), whose captain was the decorated ace Kapitänleutnant Heinrich Lehmann-Willenbrock. Buchheim later wrote about his experiences in the form of a novel, which was then turned into this gripping movie.