German U-Boat Bunkers & Bases

8/3/2019 German U-Boat Bunkers & Bases

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Overview ofOverview ofGERMANGERMAN

UU--BOAT BASES ANDBOAT BASES AND

BUNKERSBUNKERS

19411941 -- 19451945J. David RogersJ. David Rogers


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BACKGROUND 1BACKGROUND 1

German UGerman U--Boat fleet under the commandBoat fleet under the command

ofof KonteradmiralKonteradmiral KarlKarl DonitzDonitz..

As World War II erupts in SeptemberAs World War II erupts in September

1939, the U1939, the U--Boat shows its potential:Boat shows its potential:

Penetrated Royal Navy Home FleetPenetrated Royal Navy Home Fleetanchorage atanchorage at ScapaScapa Flow, ScotlandFlow, Scotland

Sank the battleshipSank the battleship HMSHMSRoyal OakRoyal Oak Escaped with easeEscaped with ease


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Shots firedLocation of the Royal Oak

Underwater obstacles


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BACKGROUNDBACKGROUND -- 22

Late spring and summer of 1940, the GermanLate spring and summer of 1940, the Germanjuggernaut invaded Norway, France and thejuggernaut invaded Norway, France and theLow Countries, overwhelming all of them in aLow Countries, overwhelming all of them in a

matter of weeks.matter of weeks. Germany took control of the port facilitiesGermany took control of the port facilities

available to them.available to them.

Prior to this acquisition, the distance toPrior to this acquisition, the distance toopen sea from German ports in the Balticopen sea from German ports in the Balticlimited their range while also increasinglimited their range while also increasing

wear and vulnerability.wear and vulnerability. The down side was that all the new portsThe down side was that all the new ports

were within easy striking distance ofwere within easy striking distance ofBritish bombersBritish bombers..


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1170

Patrols madefrom these 3

locations


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BACKGROUNDBACKGROUND -- 33

Prior to war, UPrior to war, U--Boats were usually servicedBoats were usually servicedalongside their designated flotilla tender.alongside their designated flotilla tender.

UU--Boats are more vulnerable to damage thanBoats are more vulnerable to damage than

surface vessels:surface vessels: If their pressure hull integrity isIf their pressure hull integrity is

compromised, a Ucompromised, a U--Boat would be unable toBoat would be unable to

dive.dive. Most UMost U--Boats were not fit with adequateBoats were not fit with adequate

firepower to protect themselves on thefirepower to protect themselves on the

ocean surface.ocean surface. Biggest vulnerability was detection andBiggest vulnerability was detection and

attack by enemy aircraftattack by enemy aircraft


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Limited AntiLimited Anti--Aircraft firepowerAircraft firepower

U-Boats were initially fitted witha single 20 mm AA gun; laterincreasing to two (shown at left)and then four barrelconfiguration, shown below

Some specially-fitted U-flakboats were equipped with quadmount 2.2 cm anti-aircraft guns toprovide additional AA protectionfor Wolf Packs.


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Concrete Pens Constructed toConcrete Pens Constructed to

Protect the UProtect the U--Boats in coastal portsBoats in coastal ports The Germans preThe Germans pre--war labor forcewar labor force

consisted of approximately 300,000consisted of approximately 300,000laborers.laborers.

After the outbreak of WW2, POWs andAfter the outbreak of WW2, POWs and

concentration camp inmates were put toconcentration camp inmates were put towork.work.

Approximately 15,000 laborers wereApproximately 15,000 laborers wereneeded to construct a massive Uneeded to construct a massive U--BoatBoatbunker.bunker.


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Construction of UConstruction of U--Boat PensBoat Pens

Construction proceeded 24 hours a dayConstruction proceeded 24 hours a dayusing two 12 hour shiftsusing two 12 hour shifts

Lights were used to facilitate workLights were used to facilitate workthroughout the night (except when underthroughout the night (except when under

attack)attack)

Hazardous working conditionsHazardous working conditions


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Construction OperationsConstruction Operations

Materials were initially transported fromMaterials were initially transported fromGermanyGermany

Cement in 50kg sacksCement in 50kg sacks Reinforcing SteelReinforcing Steel

Material requirements were vast, theyMaterial requirements were vast, theywere sourced locally and transported:were sourced locally and transported:

RailroadRailroad

BargesBarges

TrucksTrucks


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BUNKER DESIGNBUNKER DESIGN

Wet and DryWet and Dry

Docks in coveredDocks in covered

bombbomb--proof baysproof bays Lock gatesLock gates

OfficesOffices

Storage facilitiesStorage facilities

Machine ShopsMachine Shops

GeneratorsGenerators


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BUNKER DESIGNBUNKER DESIGN

Each pen was designed as a free-standing drydock so essentialmaintenance and battle damage repairs

could be carried out between combatdeployments


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PRODUCTION BUNKER LAYOUTPRODUCTION BUNKER LAYOUT

TheTheGermansGermans

alsoalsoenclosedenclosedall their Uall their U--

BoatBoatproductionproductionfacilities tofacilities toresistresistAlliedAllied

bombingbombing


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COASTAL BUNKER DESIGNCOASTAL BUNKER DESIGN

Biggest design concern was overheadprotection from Allied bombing

Initial construction was bomb proof; butthe bombs got bigger as war dragged on


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PROTECTION UPGRADESPROTECTION UPGRADES

Re concrete roof reinforced thicknessup to 7 meters

Fangrost screens constructed on roofs

The RAF developed12,000 lb Tallboy and22,000 Grand Slam bombs

to interdict U-Boat pens


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DEFENSIVE OPERATIONSDEFENSIVE OPERATIONS

As warAs warprogressed,progressed,biggest fearbiggest fear

was low flyingwas low flyingfightersfighters

Torpedo orTorpedo orbomb lobbomb lob

BarrageBarrage

balloons,balloons,torpedo net,torpedo net,

AA positions,AA positions,steel doorssteel doors


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BOMB DAMAGE ASSESSMENTBOMB DAMAGE ASSESSMENT

This aerial image shows craters caused by Allied air attacks beforeemplacement of fangrost covers to absorb bomb detonations.


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PRESENT DAY USEPRESENT DAY USE

TheThe LorientLorient, France, France bvunkersbvunkers are used byare used bythe French Navy as storage for nuclearthe French Navy as storage for nuclear

submarinessubmarines


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The bunkers at Brest, France are stillThe bunkers at Brest, France are still

operated by the French Navyoperated by the French Navy


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The massive bunker complex inThe massive bunker complex in

Bordeaux, France is privately held andBordeaux, France is privately held and

andand used for storage.used for storage.


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The bunkers inThe bunkers in BerganBergan, Norway are still, Norway are stillused by the Norwegian Navyused by the Norwegian Navy

PRESENT DAY USE


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St.St. NazaireNazaire, France was a French Naval, France was a French Navalfacility for awhile, and is now used asfacility for awhile, and is now used as

civilian storage facilitycivilian storage facility

REFERENCES


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REFERENCESREFERENCES

UU--Boat Bases and Bunkers 1941Boat Bases and Bunkers 194119451945,,

Gordon Williamson.Gordon Williamson.

www.uboat.netwww.uboat.net

www.uboatwww.uboat--bases.combases.com

UU--Boat WarBoat War,, LotharLothar--GuntherGunther BuchheimBuchheim..

UU--Boats Under the SwastikaBoats Under the Swastika, J.P., J.P.

MallmannMallmann ShowellShowell..

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German U-Boat Bunkers & Bases