The submarine base of Saint-Nazaire is a large fortified U-Boot

U-boot

U-boot can refer to:* U-boats, military submarines operated by Germany during World War I and World War II* Das U-Boot, also known simply as U-Boot, a computer software which serves as a bootstrap loader in many embedded systems....

 pen built by the Germans during the Second World War in Saint Nazaire.

It is one of the five large submarine bases built by the Third Reich in Occupied France.

History

Before the Second World War, Saint-Nazaire was one of the largest harbours of the Atlantic coast of France. During the Battle of France

Battle of France

In the Second World War, the Battle of France was the German invasion of France and the Low Countries, beginning on 10 May 1940, which ended the Phoney War. The battle consisted of two main operations. In the first, Fall Gelb , German armoured units pushed through the Ardennes, to cut off and...

, the German Army arrived in Saint Nazaire in June 1940. The harbour was immediately used for submarine operations, with U-46 arriving as soon as 29 September 1940.

In December, a mission of the Organisation Todt

Organisation Todt

The Todt Organisation, was a Third Reich civil and military engineering group in Germany named after its founder, Fritz Todt, an engineer and senior Nazi figure...

 (Oberbauleitung Süd) inspected the harbour to study the possibilities to build a submarine base invulnerable to air bombing from England. Work soon began under the supervision of engineer Probst.

The selected space was that of the docks and buildings of the Compagnie Générale Transatlantique

Compagnie Générale Transatlantique

The Compagnie Générale Transatlantique , typically known overseas as the French Line, was a shipping company established during 1861 as an attempt to revive the French merchant marine, the poor state of which was indicated during the Crimean War of 1856...

, that were rased. Building began in February 1941 with pens 6,7 and 8, completed in June 1941. From July 1941 to January 1942, pens 9 through 14 were built; and between February to June 1942, pens 1 through 5. Work was eventually completed by the building of a tower.

Between late 1943 and early 1944, a fortified lock

Lock (water transport)

A lock is a device for raising and lowering boats between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water level can be varied; whereas in a caisson lock, a boat lift, or on a canal inclined plane, it is...

 was built to protect submarines during their transfer from the Loire river and the pens. The lock is 155 metre long, 25 metre wide, and 14 metre high; the roof features anti-aircraft armament.

Design

The base is 300 metre long, 130 metre wide and 18 metre high, amounting to a 39,000 m² surface on the ground, and a volume of concrete of 480,000 m³. The roof is 8 metre deep, featuring four layers: the first one is a 3.5 metre sheet of reinforced concrete; the second is a 35 cm granite and concrete layers; the third is a 1.7 metre deep layer of reinforced concrete, and the fourth, is a "Fangrost" layer of steel beams, 1.40 metres deep. The roof is dotted with anti-aircraft weaponry, machine guns and mortars.
The base offers 14 submarine pens. Pens 1 through 8 are dry dock

Dry dock

A drydock is a narrow basin or vessel that can be flooded to allow a load to be floated in, then drained to allow that load to come to rest on a dry platform...

s, 92 metre long and 11 metre wide; pens 9 through 14 are simple docks, 62 metre long and 17 metre wide, each holding two submarines.

Between pens 5 and 6, and 12 and 13, are two areas giving access to the upper levels of the base.

The base was equipped with 62 workshops, 97 magazines, 150 offices, 92 dormitories for submarine crews, 20 pumps, 4 kitchens, 2 bakeries, two electrical plants, one restaurant and a hospital.

The Ville-Port

The zone of the base was abandoned for a long time. In 1994, the municipality of Saint-Nazaire decided to re-urbanise the base, in a project name Ville-Port (lit: "city-harbour").

The base now features several museums, including a mockup of a transatlantic liner, and the submarine Espadon.