Download The U-boat Threat: Countermeasures

WW II -- Second Battle of the Atlantic
Lesson Objectives
• Understand the magnitude and significance of the Battle of the
Atlantic during World War II.
• Understand the degree of British dependence on maritime lines
of communication.
• Describe U.S. participation in the Battle of the Atlantic prior to
December 1941.
• Describe and analyze the tactics and technology used by both
sides in the Battle of the Atlantic.
• Understand the importance of code breaking in the Atlantic war.
"The only thing that ever really frightened
me during the war was the U-boat peril."
Winston S. Churchill,
The Second World War, Volume II, Their Finest Hour
1949
The Battle of the Atlantic Begins
( 0:50 – 8:00 )
"The Circle of Modern War" and logo
© Thomas D. Pilsch 2007-2013
Surface Raiders
• Disruptive, but too few
• Pocket BB’s: Graf Spee, Deutschland (Lutzow)
– 6 x 11 in. guns, 26 knots: Outrun what they can’t outfight
• Armed merchants
• Battle Cruisers (Scharnhorst, Gneisenau)
– 31 knots, 9 x 11 inch guns
• Battleships (Bismarck, Tirpitz)
– 28 knots, 15 inch Guns, heavy armor, most powerful in the World
• E-Boats: very fast 50 knots, wood hull, torpedo boats
• Magnetic mines
– Explode when iron hull gets close
Threats
Surface Raiders
Pocket Battleships / Heavy Cruisers
Example: Admiral Graf Spee
Auxiliary Cruisers
Example: Atlantis
Surface Raiders
Auxiliary Cruisers/Armed Merchants
Auxiliary Cruiser Atlantis
Atlantis with dummy funnel
First auxiliary cruiser to sink a merchant ship
Circumnavigated the globe
Highest tonnage sunk of all surface raiders
• 22 ships, 146,000 tons
Surface Raiders
Pocket Battleships & Heavy Cruisers
Six 11-inch guns
Eight 5.9-inch guns
Speed: 21 knots
Displacement: 16,200 tons
Admiral Graf Spee
War Cruise
August-December 1939
Sank 9 merchant ships
(50,000 tons)
Video
Scuttled, December 17, 1939
Off Montevideo, Uruguay
After battle with thee British cruisers
The U-boat Threat
Hitler told the Kriegsmarine that the war would
(January 1939)
not begin until 1945
The Kriegsmarine built Plan Z, their expansion
blueprint, on this target
• 249 U-boats by 1944
Admiral Karl Dönitz (1891-1980)
German Submarine Commander
The U-boat Threat
Germany had 57 operational U-boats in September 1939
• Only about half of these (27) were effective ocean-going
units
Type VIIC U-boat
Range: 8,500 nm
Crew: 44-52
Torpedo load: 14
Source: The World At War
The U-boat Threat
• Plans for 300 U-boats
• Br. have only 180 escorts for Convoys
• Allied Strategy
– Protect existing shipping
•
•
•
•
Build to replace shipping losses, expand fleet
Go on the offensive against the U-boats
Employ convoy system immediately
Increase escort capability
• The “Happy Time”
– 1939-1942 From Britain all the way to US coast after Dec. 1941
• 1941- 1299 Ships lost, 1942 = 1699 Ships or 7 million tons
The U-boat Threat: Countermeasures
• Despite crisis in 1942 it is already too late for the German U –
Boat Strategy
– GB and US requisition or Charter 7 mi. tons of shipping to replace
what was lost
– US Ship Yards build 1500 “Liberty Ships” in 1943
– 200 Escort ships per year as well
– Use long range aircraft to close Mid-ocean “air-gap” and attack
surfaced subs
– German Enigma Code Machine captured and sub messages decoded
– Royal Navy codes changed after discovery that Germans had broken
Br. Codes
– HF/DF Electronic direction finders locate Ger. Subs when they transmit
by radio
– Asdic/Sonar, underwater detection system
– Hedgehog and Squid Depth Charge systems
The U-boat Threat: Countermeasures
• German Response to Allies
– Wolf-pack tactics Nov. 1942 – Feb. 1943
– Use radio to concentrate large numbers of U –Boats against a detected
convoy
– Allies quickly Counter
• This left the U-boats vulnerable to a device called (HF/DF or "Huff-Duff") which
allowed Allied naval forces to determine the location of the enemy boats
transmitting and attack them
• Also, effective air cover, both long-range planes with radar and blimps and
small aircraft carriers called Escort Carriers
• Detect and attack subs as they concentrate
Convoy System
RN employed convoys from start
• Did not have enough escorts
• Started crash construction program
USN did not use convoys initially
• Second “Happy Time” * for Germans
* Jan-Aug 1942
Ships Lost vs. Built
1939 - 1941
Source
Convoy System
Introduction of
• Aircraft
• More escorts
• Hunter-Killer tactics (later)
… turned the tide
Flower-class Corvettes
Length: 205 feet
Displacement: 940 tons
Speed: 16 knots
394 built (UK, Canada)
Video Link
Remember this one?
History doesn’t repeat itself, but it rhymes.
Attributed to Samuel Clements (1835-1910)
Unrestricted Submarine Warfare
August 17, 1940
Hitler Declares Unrestricted Blockade
Around British Isle
Unrestricted
America Submarine
Gets Involved
Warfare
August 17, 1940
Hitler Declares Unrestricted Blockade
Around British Isle
September 2, 1940
Destroyers For Bases Agreement
Destroyers For Bases
September 2, 1940
US provided 50 WW I destroyers in exchange for bases
American-British Staff Conference
Washington, DC - Jan-Mar 1941
Discussed issues of coalition warfare
“Germany First” decision
• In the event of war with Germany & Japan, defeat of
Germany would have highest priority
“Made before American entry into World War II, in the context of a world
threatened by Axis aggression in Europe and Asia, the judgment that
Germany must be defeated first stands as the most important single
strategic concept of the war.”
Louis Morton
"Germany First: The Basic Concept of Allied Strategy in World War II"
Command Decisions, Kent Roberts Greenfield (ed)
Washington: US Army Center of Military History, 2000
Events
September 2, 1940
September 16, 1940
Destroyers For Bases Agreement
Selective Training and Service Act
• First US “peacetime” draft
Jan-March 1941
American-British Staff Conference
March 11, 1941
Lend-Lease Act
April 4, 1941
British ships allowed for repairs
April 24, 1941
US warships report German navy moves
July 1941
US assumed occupation of Iceland
Events
September 1, 1941
US warships escort convoys containing
US vessels
September 11, 1941
US warships ordered to “shoot on sight”
Events
October 31, 1941
USS Reuben James sunk by U-boat
• 100 killed
USS Reuben James DD-245
Link
Destroyer Escorts
(DE)
USS Slater (DE-766)
Displacement: 1,240 tons (std) 1,620 tons (full) Dimensions: 306' (oa), 300' (wl) x 36' 10" x 11' 8" (max)
Armament: 3 x 3"/50 Mk22 (1x3), 1 twin 40mm Mk1 AA, 8 x 20mm Mk 4 AA, 3 x 21" Mk15 TT (3x1),
1 Hedgehog Projector Mk10 (144 rounds), 8 Mk6 depth charge projectors, 2 Mk9 depth charge tracks
Machinery: 4 GM Mod. 16-278A diesel engines with electric drive, 6000 shp, 2 screws
Speed: 21 knots Range: 10,800 nm @ 12 knots Crew: 15 / 201
Source
Destroyer Escorts
(DE)
Fleet destroyer
Fletcher class
Destroyer Escort
Cannon class
Destroyer escorts did not need speed of fleet destroyers
• 21 knots vs. 35 knots for destroyers
DEs could be smaller, cheaper, easier to produce
Other Threats
FW 200 Condor Maritime Patrol Aircraft
Source
Catapult Armed Merchantmen
HAWKER “HURRICAT”
Source
Source
Catapult Armed Merchantman (CAM)
( 15:05 – 16:40 )
"The Circle of Modern War" and logo
© Thomas D. Pilsch 2007-2013
All was ruled by that harsh and despotic factor,
shipping.
Winston S. Churchill,
The Second World War, Volume III, The Grand Alliance
1950
Liberty Ships
Based on a British design
• Simple, welded hull
• Proven 1890-era steam engine
Originally tagged “ugly duckling” by FDR
“Liberty” campaign by Maritime Commissioner Emory Land changed image
• First ship: Patrick Henry
• Liberty Fleet Day: 15 ships launched across country (Sept. 27, 1941)
Liberty Ships
SS Jeremiah O’Brien
National Liberty Ship Memorial
Speed: 11 knots
Royal Navy Photo
One of 2,718 built at 17 US shipyards
Source
Source
Victory Ships
Larger, faster than Liberty ship
550 built
SS United Victory
Source
T-2 Tankers
533 built
Source
SS Huntington Hills (completed in 33 days)
• 523 feet long overall
• 68 foot beam
Source
• 30 foot draft
• 10,448 Gross tons
• 21,880 Loaded displacement tons
• 6,000 shaft horsepower Turbo-Electric propulsion
• Speed 14.5-16 knots
Aircraft on “skeleton deck”
• Liquid capacity 141,200 barrels (nearly 6 million gal)
Source
Allied Strategy
• Protect existing shipping
• Build to replace shipping losses, expand fleet
• Go on the offensive against the U-boats
• Improve intelligence on U-boat operations
• Close Mid-Atlantic Gap
• Develop Hunter-Killer teams
Signals Intelligence
( SIGINT )
Enigma
Source
Enigma
Source
Enigma
Bletchley Park
Source
Alan Turing’s “Bombe”
Enigma
British intelligence received its first Enigma
machine in 1939 from Polish military
Additional machines captured by Royal Navy
• May 9, 1941: U-110 off Iceland
• October 30, 1942: U-559 in the Mediterranean
USN captured U-505, June 4, 1944
Source
Direction Finding
( ELINT )
High Frequency Direction Finding (HF/DF)
“Huff-Duff”
German subs required to report positions
Allies used information to reroute convoys
• Later used to direct Hunter- Killer task forces
Mid-Atlantic Gap
Source: The World At War
Maritime Patrol Aircraft
USAAF A-29 Hudson
RAF Liberator
Blimps
RAF Fortress
Source
Maritime Patrol Aircraft
Caught On The Surface – Robert Taylor
RAF Sunderland Flying Boat – Coastal Command vs. U-461
20 July 1943 – Bay of Biscay
Source
Airborne Detection Tools
Leigh Light
Powerful aircraft light for night attacks
Introduced June 1942
Airborne Detection Tools
Airborne Radar
Antenna Detail
RAF Coastal Command Liberator Mk III with ASV radar
Permitted location of submarines in bad weather and at night
First U-boat kill November 1941
Pioneering video documentary 1952-53
Going on the Offensive
(0 – 7:04)
"The Circle of Modern War" and logo
© Thomas D. Pilsch 2007-2013
Escort Carrier
Built in Kaiser shipyards on T-3 tanker hulls
USS Bogue
T-3 Tanker
Escort Carrier
Comparison With Fleet Carrier
USS Bogue
CVE-9
Laid Down: 1 Oct 41
Launched: 15 Jan 42
Commissioned: 28 Sep 42
Displacement: 7,800 tons standard; 15,700 tons full load (design)
Length: 495' 8" (151.1 m)
Beam: 111.5' (34 m)
Power plant: 2 boilers (285 psi); 1 steam turbine; 1 shaft; 8,500 shp
Speed: 16.5 knots
Armament: 2 single 5"/51 (later 5"/38) gun mounts; (1943) 8 twin 40mm/56-cal gun mounts; (1943) 27 single 20-mm/70-cal gun mounts
Aircraft: 24
Aviation facilities: 2 elevators; 1 hydraulic catapult
Crew: 890
Source
Hunter-Killer Team
Slide 8
Hunter Becomes the Hunted
U-118 under attack by aircraft from USS Bogue
June 12, 1943
Source
May 1943: The Turning Point
“What is now decisive is that enemy aircraft have
been equipped with a new location apparatus …
which enables them to detect submarines and
attack them in low cloud, bad visibility, or at nights.
Much the largest number of submarines now being
sunk are being sunk by aircraft. … These losses are
too high. We must now husband our resources
because, to do anything else, would simply be to
play the enemy’s game”
Admiral Dönitz to Hitler, May 1943
Source
U-boat Losses By Month
U-boat.net
Ship Losses 1940 - 1945
Ships Lost vs. Built
1939-1945
Source
US Shipbuilding
Ships Built by US Maritime Commission
1939-1947
Source
5,500+ ships
US Maritime Commission
Losses
Museum of Science & Industry, Chicago
"The Battle of the Atlantic was the dominating
factor all through the war. Never for one
moment could we forget that everything
happening elsewhere, on land, at sea, in the air,
depended ultimately on its outcome.”
Winston S. Churchill,
The Second World War, Volume V, Closing the Ring
1951