4 Convoy Presentation Final V1.1
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ALLIED CONVOY OPERATIONS IN THE BATTLE OF THE ATLANTIC 1939-43 INTRODUCTION • History of Allied convoy operations IS the history of the Battle of the Atlantic • Scope of this effort: convoy operations along major transatlantic convoy routes • Detailed overview • Focus on role of Allied intelligence in the Battle of the Atlantic OUTLINE • Convoy Operations in the First Battle of the Atlantic, 1914-18 • Anglo-Canadian Convoy Operations, September 1939 – September 1941 • Enter The Americans: Allied Convoy Operations, September 1941 – Fall 1942 • The Allied Convoy System Fully Realized: Allied Convoy Operations, Fall 1942 – Summer 1943 THE FIRST BATTLE OF THE ATLANTIC, 1914-18 • 1914-17: No convoy operations § All vessels sailed independently • Kaiserliche Marine use of U-boats primarily focused on starving Britain into submission § Prize rules • February 1915: “Unrestricted submarine warfare” § May 7, 1915 – RMS Lusitania u U-20 u 1,198 dead – 128 Americans • February 1917: unrestricted submarine warfare resumed § Directly led to US entry into WWI THE FIRST BATTLE OF THE ATLANTIC, 1914-18 • Unrestricted submarine warfare initially very effective § 25% of all shipping bound for Britain in March 1917 lost to U-boat attack • Transatlantic convoys instituted in May 1917 § Dramatically cut Allied losses • Post-war, Dönitz conceptualizes Rudeltaktik as countermeasure to convoys ANGLO-CANADIAN CONVOY OPERATIONS, SEPTEMBER 1939 – SEPTEMBER 1941 GERMAN U-BOAT FORCE AT THE BEGINNING OF THE WAR • On the outbreak of WWII, Hitler directed U-boat force to comply with prize rules § London Treaty, 1930 • Complete unrestricted submarine warfare instituted by 1940 • U-boat force consisted of 57 vessels § Only 37 ready for combat ◆ 1 Type I ◆ 18 Type II ◆ 13 Type VII ◆ 5 Type IX OPENING MOVES, 1939 • UK immediately instituted convoy system on 03 September § All vessels to sail in convoy except those ◆ Faster than 15 knots ◆ Slower than 9 knots • Seven Royal Canadian Navy destroyers placed under operational control of Royal Navy KEY CONVOY ORGANIZATIONS • Admiralty Naval Staff § Trade Division § Naval Intelligence Division ◆ Operational Intelligence Centre • Western Approaches Command • RAF Coastal Command ADMIRALTY TRADE DIVISION • Responsible for organization and control of the Naval Control of Shipping organization § Naval officers at UK ports that controlled all in-bound and out-going merchant vessels • Controlled the movement of all merchant ships and convoys § Decided if a ship was to proceed in convoy or independently § Allocated merchant ships to specific convoys • Assigned Convoy Commodores for command of specific convoys • Maintained Admiralty Trade Plot § Current location of all British merchant shipping world-wide • Direct the arming and equipping of merchant ships • Conducted close liaison with other Admiralty departments – OIC, Ministry of War Transport OPERATIONAL INTELLIGENCE CENTRE • 1939 – OIC organization § Submarine Tracking Room § German Surface Ship Section § Italian– Japanese Section § High Frequency Direction Finding (HF/DF) Section § Liaison ◆ To Air Ministry Intelligence Department ◆ From Naval Section (Hut 4) of GC&CS • Late 1940 – Rodger Winn commissioned as Temporary Commander, RNVR § Commander, Submarine Tracking Room SOURCES OF INTELLIGENCE • Signals Intelligence § Special Intelligence § HF/DF § Traffic analysis § TINA § Radio fingerprinting • Photographic (aerial) reconnaissance • Fleet reports • Agent reports • PoW interrogation reports WESTERN APPROACHES COMMAND • Major operational command of the Royal Navy § Located in Plymouth September 1939-February 1941 § Moved to Derby House, Liverpool in February 1941 • Exercised direct command of all convoy escorts and Escort Groups § Allocated specific escort vessels to specific convoys • Controlled the movement (course, speed, etc) of convoys while at sea • Coordinated with RAF Coastal Command for air cover RAF COASTAL COMMAND • Formed 1936 • Began the war with only five squadrons of aircraft suitable for long-range maritime ASW • Short Sunderland amphibious aircraft (3 squadrons) • Lockheed Hudson (2 squadrons) • 1940 - Catalina I (PBY-5) amphibious aircraft § 210 Squadron, RAF Oban, Scotland • 1941 – Liberator I (B-24) long-range ASW aircraft § 120 Squadron, RAF Nutts Corner, N. Ireland; Reykjavik, Iceland INITIAL CONVOY SYSTEM • Initial convoy system established by October 1939 • Initial routes established: § Halifax-Liverpool (HX/HXF) • Initially divided into fast (12-15 kt) convoys (HXF) and slow (9-12 kt convoys) § Gibraltar-Liverpool (HG)/Liverpool-Gibraltar (OG) § Sierra Leone-Liverpool (SL) § Liverpool Outbound (OB) § Convoy dispersed at 50N, 26W (about 750 NM W of Lands End) • Sep 39 – Late 1940 - convoy escorts assigned on ad-hoc basis • Sep 1939 – May 1940 § Canada-based escorts escorted convoys from Halifax/Sydney as far as the Grand Banks § Royal Navy escorted convoys from 22∘W to Liverpool § Convoys unescorted for ~1,090 NM BRITISH DESTROYER SITUATION, 1939-41 • Royal Navy entered WWII with ∼175 fleet destroyers § 91 “modern” destroyers (built 1927-39) § H-class (Havant-class) § Remainder of WWI vintage § V- and W-class • Flower-Class Corvette under development sinCe mid- H class destroyer HMS Harvester 1939 § Began entering the fleet (RCN) in April 1940 • Late 1940: 50 WWI-vintage “four stack” destroyers provided by US under “destroyers for bases agreement” to Royal Navy and Royal Canadian Navy V class destroyer HMS Viceroy PRIMARY BRITISH CONVOY ESCORT VESSELS • WWI-era V and W class destroyer • H-class destroyer W-class destroyer HMAS Waterhen • US Town-class “four stack” destroyers • Flower-class corvette Havant-class destroyer HMS Hesperus TOWN-CLASS DESTROYERS • Three US classes of destroyers provided to the UK under the “Destroyers For Bases Agreement” (September 1940) § Caldwell § Wickes § Clemson • Referred to by Royal Navy as “Town” class due to USS Craven/HMS Lewes renaming for population centers in the US and Caldwell-class destroyer UK having a shared name • World War I-era vessels § 4 stacks § Prone to roll § Twin screws rotating the same direction § Large turning radius USS Aaron Ward/HMS Castleton Wickes-class destroyer TOWN-CLASS DESTROYERS • Speed: 30-35 knots • 1,020 – 1,190 tons • ∼350 ft in length • ∼31 ft in beam • Armament § 3 x 4” guns § 1 x 3” AA gun § 2 x triple torpedo tubes § Later fitted with depth charges, hedgedogs USS Aulick/HMS Burnham Clemson-class destroyer FLOWER-CLASS CORVETTE • Also known as Gladiolus class § Commissioned April 1940 • Based on civilian design for whale-catcher • Originally intended for UK coastal convoys § Presses into service for Transatlantic escort due to range § Mainstay of Mid-Ocean Escort Force • 294 total units produced HMCS Regina • Used extensively in Royal Navy, Royal Canadian Navy § 10 served in US Navy § Also Free French, Dutch, Norwegian, Greek navies HMCS Battleford FLOWER-CLASS CORVETTE • Speed: 16 knots • 940 tons • 205 ft in length • 33 ft in beam • Armament § 1 x 4” guns § 2 x .50 cal MG § 2 x .30 cal MG § 2 x Mk II depth- charge throwers HMS Buttercup § 2 x depth charge 1942 rails CONVOY COMPOSITION AND FORMATIONS FS FS DD AK AK AK AK AK AK AK AK AK AOG AK AK DD AK AOG AOG AK AK AK AOG AK AK AK AK AK AK AK AK AK FS DD FS 1,000 yards between columns 600 yards between ships 2 miles between DD screen and convoy CHANGES TO CONVOY SYSTEM, 1940 • May 1940 • UK occupies Iceland • Began construction on facilities to re-arm, re-fuel convoy escorts • August 1940 – Slow (9-12 kt) convoys from NortH America began originating in Sydney, Nova Scotia from 15 August (SC) • U-boat Happy Time - June- December 1940 • 360+ ships; 2,000,000 tons sunk DEVELOPMENTS IN THE CONVOY SYSTEM, 1941 • Early 1941 – Western Approaches Command forms Escort Groups § Permanent tactical organizations of 4-8 ships each § Sometimes composed of same class of vessel § Conducted Group training to perform as a team during convoy operations § Total of 8 Escort Groups formed by Fall 1941 • April 15, 1941 – Admiralty assumed operational control of RAF Coastal Command HMCS Saskatchewan in St John’s harbor • June 1941 § Royal Canadian Navy moves escort force from Halifax to St John’s, Newfoundland, forms Newfoundland Escort Force § First transatlantic eastbound convoy (HX129 ) escorted “end to end.” • July 1941 – Liverpool-Halifax (ON) and Liverpool-Sierra Leone (OS) convoys replaced Liverpool Outbound (OB) convoys ST JOHN’S ESCORT FORCE ST JOHN’S ESCORT FORCE AUGUST 1941: NAVAL ENIGMA BROKEN • GC&CS broke German naval Enigma for the first time in the war • Dramatically changed British intelligence picture of U-boat activities IMPACT OF BREAKING NAVAL ENIGMA • Deciphered Enigma U-boat messages immediately transmitted to Submarine Tracking Room • For the first time, enabled Submarine Tracking Room to build a comprehensive, accurate picture of the U-boat force § Disposition and movement of all operational U-boats in North Sea and Atlantic • BdU SOP: Patrol orders and instructions sent via HF morse after boat was at sea § Intercept/decipherment of these transmissions provided unique insights into impending U-boat operations OPS-INTEL FUSION OF SPECIAL INTELLIGENCE • Submarine Tracking Room maintained an Atlantic plot depicting: § Current estimated position of all U-boats at sea § Positions and routes of British warships, convoys, and independently routed merchant vessels • Allowed Admiralty to re-route convoys around U-boat concentrations SITUATION, SEPTEMBER 1941 • Convoy system fully established § Command and staff structure