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 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 "The Circle of Modern War" and logo © Thomas D. Pilsch ( 0:50 – 8:00 )

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 Highest tonnage sunk of all surface raiders Circumnavigated the globe 22 ships, 146,000 tons

Surface Raiders Pocket Battleships & Heavy Cruisers Admiral Graf Spee Six 11-inch guns Eight 5.9-inch guns Speed: 21 knots Displacement: 16,200 tons Scuttled, December 17, 1939 Off Montevideo, Uruguay After battle with thee British cruisers War Cruise August-December 1939 Sank 9 merchant ships (50,000 tons) Video

The U-boat Threat Admiral Karl Dönitz ( ) German Submarine Commander Hitler told the Kriegsmarine that the war would not begin until 1945 The Kriegsmarine built Plan Z, their expansion blueprint, on this target 249 U-boats by 1944 (January 1939)

The U-boat Threat Type VIIC U-boat Range: 8,500 nm Crew: 44-52Torpedo load: 14 Germany had 57 operational U-boats in September 1939 Only about half of these (27) were effective ocean-going units

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” – From Britain all the way to US coast after Dec 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 – Feb – 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 Source

Convoy System Introduction of Aircraft … turned the tide More escorts Hunter-Killer tactics (later)

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 ( )

Unrestricted Submarine Warfare August 17, 1940 Hitler Declares Unrestricted Blockade Around British Isle

Unrestricted Submarine Warfare August 17, 1940 Hitler Declares Unrestricted Blockade Around British Isle America Gets Involved 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 “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 “Germany First” decision In the event of war with Germany & Japan, defeat of Germany would have highest priority

Events September 2, 1940 Destroyers For Bases Agreement September 16, 1940Selective Training and Service Act Jan-March 1941American-British Staff Conference First US “peacetime” draft March 11, 1941 Lend-Lease Act British ships allowed for repairs April 4, 1941 US warships report German navy moves April 24, 1941 July 1941US assumed occupation of Iceland

Events September 1, 1941 US warships escort convoys containing US vessels September 11, 1941US 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) 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 A diesel engines with electric drive, 6000 shp, 2 screws Speed: 21 knots Range: 10, knots Crew: 15 / 201 USS Slater (DE-766) Source

Destroyer Escorts (DE) Fleet destroyer Fletcher class Destroyer Escort Cannon class Destroyer escorts did not need speed of fleet destroyers DEs could be smaller, cheaper, easier to produce 21 knots vs. 35 knots for destroyers

Other Threats FW 200 Condor Maritime Patrol Aircraft Source

Catapult Armed Merchantmen Source HAWKER “HURRICAT”

Catapult Armed Merchantman (CAM) "The Circle of Modern War" and logo © Thomas D. Pilsch ( 15:05 – 16:40 )

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 Royal Navy Photo SS Jeremiah O’Brien National Liberty Ship Memorial Source One of 2,718 built at 17 US shipyards Speed: 11 knots

Victory Ships Larger, faster than Liberty ship 550 built Source SS United Victory

T-2 Tankers Source Aircraft on “skeleton deck” 533 built Source SS Huntington Hills (completed in 33 days) 523 feet long overall 68 foot beam 30 foot draft 10,448 Gross tons 21,880 Loaded displacement tons 6,000 shaft horsepower Turbo-Electric propulsion Speed knots 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 Source Enigma ( SIGINT )

Enigma Source

Enigma Source Bletchley Park Alan Turing’s “Bombe”

Enigma Source 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

Direction Finding High Frequency Direction Finding (HF/DF) “Huff-Duff” ( ELINT ) German subs required to report positions Allies used information to reroute convoys Later used to direct Hunter- Killer task forces

Source: The World At War Mid-Atlantic Gap

Maritime Patrol Aircraft Source RAF Liberator USAAF A-29 Hudson RAF Fortress Blimps

Maritime Patrol Aircraft Caught On The Surface – Robert Taylor RAF Sunderland Flying Boat – Coastal Command vs. U 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 Permitted location of submarines in bad weather and at night First U-boat kill November 1941 RAF Coastal Command Liberator Mk III with ASV radar Antenna Detail

Pioneering video documentary

Going on the Offensive "The Circle of Modern War" and logo © Thomas D. Pilsch (0 – 7:04)

Escort Carrier T-3 Tanker USS Bogue Built in Kaiser shipyards on T-3 tanker hulls

Escort Carrier Comparison With Fleet Carrier

USS Bogue CVE-9 Source 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 40- mm/56-cal gun mounts; (1943) 27 single 20-mm/70-cal gun mounts Aircraft: 24 Aviation facilities: 2 elevators; 1 hydraulic catapult Crew: 890 Laid Down: 1 Oct 41 Launched: 15 Jan 42 Commissioned: 28 Sep 42

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

Ships Lost vs. Built Source

US Shipbuilding Source Ships Built by US Maritime Commission US Maritime Commission 5,500+ ships

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