VLR B-24 Liberators and the Mid-Atlantic Gap
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Shortround6
Major General
Most histories seem to say politics. As in strategy/tactics.
Some leaders could not grasp that the mere presence of aircraft, even if actual U-boat sinkings were minimal, significantly reduced the U-boats effectiveness and significantly reduced the number of merchant ships sunk.
Bombing Sub bases and building yards was viewed as more "offensive" in spirit and the results were badly over estimated.
Some leaders could not grasp that the mere presence of aircraft, even if actual U-boat sinkings were minimal, significantly reduced the U-boats effectiveness and significantly reduced the number of merchant ships sunk.
Bombing Sub bases and building yards was viewed as more "offensive" in spirit and the results were badly over estimated.
syscom3
Pacific Historian
B24's were not in abundance until 1944. Everything being built prior to then was going to operational units and to make good for war losses.
Shortround6
Major General
Coastal command was an operational "unit".
British got 20 of the first production batch of 38 B-24As after the fall of France. One was damaged during delivery so British recieved 19. Went into service with 120 Squadron of Coastal Command in June of 1941, went out of service Dec 1943 beieng replaced by later Marks. A few were used as long rang transports. The LB-30B/Liberator I didn't have power turrets or turbos.
The British ordered 165 Liberator IIs in 1941 and 140 were built, one crashed and the US may have requisitioned up to 75 aircraft from the British (or added to the order?). The British aircraft got British power turrets. 3 Coastal command squadrons and two bomber command squadrons operated them. I don't know if they got full compliments. At least 16 were operated as freighter/transports by BOAC.
British got 366 Liberator IIIs starting in June of 1942. These were the first British Liberators with turbos. The British used few, if any, Liberators as bombers in Europe, most bomber command Liberator squadrons operating in the Middle East or Far East.
Ensuring British supply lines to England should NOT have been seen as a secondary theater and dumping ground for aircraft deemed unsuitable for front line operations.
British got 20 of the first production batch of 38 B-24As after the fall of France. One was damaged during delivery so British recieved 19. Went into service with 120 Squadron of Coastal Command in June of 1941, went out of service Dec 1943 beieng replaced by later Marks. A few were used as long rang transports. The LB-30B/Liberator I didn't have power turrets or turbos.
The British ordered 165 Liberator IIs in 1941 and 140 were built, one crashed and the US may have requisitioned up to 75 aircraft from the British (or added to the order?). The British aircraft got British power turrets. 3 Coastal command squadrons and two bomber command squadrons operated them. I don't know if they got full compliments. At least 16 were operated as freighter/transports by BOAC.
British got 366 Liberator IIIs starting in June of 1942. These were the first British Liberators with turbos. The British used few, if any, Liberators as bombers in Europe, most bomber command Liberator squadrons operating in the Middle East or Far East.
Ensuring British supply lines to England should NOT have been seen as a secondary theater and dumping ground for aircraft deemed unsuitable for front line operations.
I agree, but everyone is looking at this with 21st century eyes.
Ensuring the safety of trans Atlantic trade routes, and all the others across the Empire, was primarily perceived as the job of the Royal Navy. It was the raison d'etre of that service. Very few naval officers had any concept of how useful aircraft might be, nor how to use them.
Cheers
Steve
oldcrowcv63
Tech Sergeant
There may have also been a misperception that convoy-accompanying CVE's (AFAIK emerging in small numbers in late '42) would be adequate to close any remaining gap. Might seem like a good idea until one does the math and realizes that, as good as carrier based air can be, it'e aerial coverage footprint (~200 mile radius around the flight deck), is woefully small compared to the much larger expanse of the ocean. An extrapolation might have been made from the need for coordinated land and carrier based air in SOPAC that proved so effective for both sides, but of course the perceived missions are quite different. Fleet reconnaissance vs Long Range ASW. IN any event, the lesson was well learned and long range maritime patrol aviation remains a vital if unheralded component of modern military forces.
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syscom3
Pacific Historian
By saying "Operational Units" ; I was referring to the AAF demand for B24's for its own global needs.
Shortround6
Major General
A bit of the same reasoning.
The Air Force boys ( of both countries) were trying to prove that their branch of the service was more deserving of money, resources, prestige than the other two services.
To convince the legislature/parliament they needed headlines or dispatches about damaging bombing raids that were hurting the enemy where he lived rather than a bunch of inconclusive sightings/contacts with little to show on a score board. How do you prove that that sub that submerged when sighted by an aircraft was NOT in a position to attack the convoy several hours later?
Both the US and British would have been better served by using more squadrons ( and not a lot in the overall scheme of things) of newer, better aircraft for anti-sub patrol.
The Air Force boys ( of both countries) were trying to prove that their branch of the service was more deserving of money, resources, prestige than the other two services.
To convince the legislature/parliament they needed headlines or dispatches about damaging bombing raids that were hurting the enemy where he lived rather than a bunch of inconclusive sightings/contacts with little to show on a score board. How do you prove that that sub that submerged when sighted by an aircraft was NOT in a position to attack the convoy several hours later?
Both the US and British would have been better served by using more squadrons ( and not a lot in the overall scheme of things) of newer, better aircraft for anti-sub patrol.
Shortround6
Major General
It is not so much 21st century eyes but a lot of lessons from WW I were forgotten ( or misplaced ?) between the wars. Aircraft flying anti-sub patrols had proven effective during WW I. Not so much in sinking U-boats but in restricting their operations in areas the aircraft could patrol. A submerged sub is nearly blind compared to one running on the surface and it's mobility is reduced to around 1/3-1/4 of what the surfaced sub can do. Submerged subs usually running at around 4 knts to preserve batteries.
However if you are trying to establish a "NEW" military service and fighting for equivalent ranks to Admirals and Generals you need to argue that you can win wars and fight the enemy in his homeland, not argue you can do a better job than corvettes, sloops and converted fishing trawlers.
The British managed to forget a lot about night fighting during the 20s and early 30s and even forgot (according to some stories) that night fighters could use guns that pointed up despite a variety of British fighters that used guns firing at upward angles going from B.E.2Cs to the Defiant.
There were several hundred flying boats used in addition to land aircraft during WW I. Somebody had an idea of how to use them, at least until they were retired/beached.
- Thread starter
- #10
Seems related to suppressive fire: https://en.wikipedia.org/wiki/Suppressive_fire
Perhaps there is a military term for this "restriction or denial of operations."
We've discussed on this board use of air power against armored ground units.
Post battle surveys found less damage than claimed, but the effectiveness of the armored units being attacked was greatly reduced.
While the aircraft flying the patrol don't need to maintain constant suppressive fire, just being present restricts enemy operations, like an aircraft over or a tank on a battlefield.
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It was only with the advent of the Avro Anson in 1936 that the RAF received its first land based maritime patrol aircraft, although the Blackburn Kangaroo of Great War origin was earlier, it was RNAS and in small numbers. Using land based maritime patrol assets was a relatively new concept to the British, although the RAF did operate strictly land based torpedo bombers between the wars in the Hawker Horsley, aside from its ship based aircraft aboard the navy's carriers.
This was the argument for the use of airships as maritime patrol assets. During the Great War the British had a large number of non-rigid airships, but lost its lighter-than-air capability in 1921. The RNAS claimed that no merchant ship was sunk by a enemy submarine under escort by airships, while this isn't strictly true, there being a couple of recorded incidents where merchant ships were sunk by U-boats, while under airship escort, the presense of the airships was a deterrent to attack by submarine. Non-rigid airships made ideal MPA assets as they were reasonably fast compared to the submarines they were searching for, they could carry a relatively large warload compared to aeroplanes, they had a much greater range and endurance, they could come to a stop in the air and hover over a particular area and since the Mark 1 Eyeball was the principal sensor aboard, could carry a useful number of people for spotting duties in the larger ships. The US Navy continued using airships throughout WW2. Britain had the capability to build airships, just not the desire; after the R.38 disaster, built for the US Navy as ZR-2, the British military was in no mood for LTA aircraft and lost a useful capability.
Politics played a part in the lack of effective maritime patrol aircraft. It was originally assumed that the flying boats the RAF operated were sufficient, but in fact they had considerable limitation in terms of capability and numbers and Coastal Command used whatever it could get old of, usually derivatives of heavy bombers, Wellingtons, Whitleys, Halifaxes, Warwicks and eventually Lancasters, which it requested, but Harris refused to allow any to any other command except his own. The use of American aircraft was out of a desire for greater number of assets owing to a short fall in capability, hence the Hudson, then Fortress and Liberator.
This was the argument for the use of airships as maritime patrol assets. During the Great War the British had a large number of non-rigid airships, but lost its lighter-than-air capability in 1921. The RNAS claimed that no merchant ship was sunk by a enemy submarine under escort by airships, while this isn't strictly true, there being a couple of recorded incidents where merchant ships were sunk by U-boats, while under airship escort, the presense of the airships was a deterrent to attack by submarine. Non-rigid airships made ideal MPA assets as they were reasonably fast compared to the submarines they were searching for, they could carry a relatively large warload compared to aeroplanes, they had a much greater range and endurance, they could come to a stop in the air and hover over a particular area and since the Mark 1 Eyeball was the principal sensor aboard, could carry a useful number of people for spotting duties in the larger ships. The US Navy continued using airships throughout WW2. Britain had the capability to build airships, just not the desire; after the R.38 disaster, built for the US Navy as ZR-2, the British military was in no mood for LTA aircraft and lost a useful capability.
Politics played a part in the lack of effective maritime patrol aircraft. It was originally assumed that the flying boats the RAF operated were sufficient, but in fact they had considerable limitation in terms of capability and numbers and Coastal Command used whatever it could get old of, usually derivatives of heavy bombers, Wellingtons, Whitleys, Halifaxes, Warwicks and eventually Lancasters, which it requested, but Harris refused to allow any to any other command except his own. The use of American aircraft was out of a desire for greater number of assets owing to a short fall in capability, hence the Hudson, then Fortress and Liberator.
John Huntington
Recruit
- 1
- May 10, 2019
Dad , Herbert Wallace Huntington , served from 1940 to 1945 out of Gander with Sqdn # 10 first in Digby's then on May 20th 1943 they got the VLR B-24 to close the mid Atlantic gap . On One flight they ran into bad weather and found their way to Goose Bay and started to run out of fuel while landing after 16 hours and 10 min. May be a record for the Liberator . They were very glad to be on the ground and went straight to the mess for several beer returning to Gander the next day . This was on Liberator "N" . His last operational tour was on Liderator "K" on Jan. 23rd 1944 then went to transportation flying around eastren Canada .
MIflyer
1st Lieutenant
In reality the U-boats never stopped more than 10% of the shipping going across the Atlantic. They could not win that way.
And it was not just airplanes. They needed microwave radar that could detect U-boats on the surface. The first radar equipped anti-sub B-24's were USAAF and the USN considered that their mission. So the USAAF B-24's were phased out rather than augmented with USN aircraft and the airplanes and crews, not trained for high altitude formation bombing, were switched to supplying agents and resistance movements in Occupied Europe.
Note that even the Sunderland flying boats had radios of such short range they had trouble reporting U-boats when they found them. When the first PBY was delivered to Great Britian the British they asked about the radio. Told that the radio had been working San Diego while the airplane was on final approach, they could not believe it; they went up the next day and got hold of San Diego again.
And it was not just airplanes. They needed microwave radar that could detect U-boats on the surface. The first radar equipped anti-sub B-24's were USAAF and the USN considered that their mission. So the USAAF B-24's were phased out rather than augmented with USN aircraft and the airplanes and crews, not trained for high altitude formation bombing, were switched to supplying agents and resistance movements in Occupied Europe.
Note that even the Sunderland flying boats had radios of such short range they had trouble reporting U-boats when they found them. When the first PBY was delivered to Great Britian the British they asked about the radio. Told that the radio had been working San Diego while the airplane was on final approach, they could not believe it; they went up the next day and got hold of San Diego again.
pinehilljoe
Senior Airman
- 742
- May 1, 2016
One of the better recent books on this very topic, and the U-Boat war is Blackett's War: The Men Who Defeated the Nazi U-Boats and Brought Science to the Art of Warfare.
Amazon product ASIN 030759596X
The operational research scientists supporting Coastal Command and U-Boat war argued for more VLR Air Craft to be diverted to Coastal Command. Blackett and Tizard argued the citizens of Hamburg or Cologne would hardly know the difference between a 1000 plane and a 750 plane incendiary raid, but an additional 250 planes in Coastal Command could be decisive. But they were warned they were trying to argue tactics over policy, and would never win. Also the USAF insistence on bombing the U-Boat Pens was completely futile, concrete is cheap and the pens were essentially indistructible, even if the bombing technology of the day could hit them. They are still there today, to massive to be worth demolition. If the planes bombing pens had been patrolling the Bay of Biscaye they would have been more effective.
Amazon product ASIN 030759596X
The operational research scientists supporting Coastal Command and U-Boat war argued for more VLR Air Craft to be diverted to Coastal Command. Blackett and Tizard argued the citizens of Hamburg or Cologne would hardly know the difference between a 1000 plane and a 750 plane incendiary raid, but an additional 250 planes in Coastal Command could be decisive. But they were warned they were trying to argue tactics over policy, and would never win. Also the USAF insistence on bombing the U-Boat Pens was completely futile, concrete is cheap and the pens were essentially indistructible, even if the bombing technology of the day could hit them. They are still there today, to massive to be worth demolition. If the planes bombing pens had been patrolling the Bay of Biscaye they would have been more effective.
Shortround6
Major General
Actually they could.
Each ship could make a number of round trips per year. Sink one in January and that is 6 or more round trips across the atlantic that don't get made in one year.
Just like 5-10% losses is the critical number for a sustained bombing campaign. If the germans could sink ships faster than the allies could build them then the flow of supplies to England would slow down while the actual need for increased supplies to stockpile for the planned invasion was going up.
1943 was pivotal year in the U-boat campaign for a lot of reasons. New radar, new aircraft (or at least new to anti sub work (in numbers)) new weapons (homing torpedoes,etc) and the liberty ship construction program was finally kicking in. No one weapon/factor was responsible for the shift in the situation.
pinehilljoe
Senior Airman
- 742
- May 1, 2016
Also new tactics. For example the operational research team defined the depth setting for airborne depth charges and time from submerging to dropping, to most likely sink a U-Boat. Tactics for Convoy size were also analyzed. Also, the Op Research team realized obsolete bombers given to Coastal Command were all painted black. Black planes were easier to spot, and U-Boats could sometimes see the plane before being spotted themselves. Painting Coastal Command aircraft white, gave more time before they were spotted by the U-boat. This was all analysis and research on how to better use the weapons at hand.
In his memoirs Blackett wrote his biggest mistake was not evaluating the optimal size of convoys earlier. He estimated he could have saved 1 Million tons of shipping if 80 to 100 ship convoys were implemented in '42. Concentrating on the patrolling the Bay of Biscaye was another turning point.
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MIflyer
1st Lieutenant
But they did not stop more than 10% of the supplies, even though the ships they sank were capable of more than one trip. Read Hitler's U-Boat War by Clay Blair; he explains this. We did react to the U-boat success, built ships faster than they could sink them, and in 1944 were sinking something like 10 times the tonnage in U-boats that they were sinking in our ships. The Germans lost 500 U-boats in WWII, 10 times as many as the USN.
Aggressors: Patrol Aircraft vs. Submarine describes the history of Liberator MK 1 AM929. Built in May 1941, during its service it drove off an FW-200 that was attacking a convoy, sighted 25 U-boats and damaged a number, sank U-597, sank U-661, sank U-132 , sank U-194, and helped to sink U-540. The best record, ever!
Aggressors: Patrol Aircraft vs. Submarine describes the history of Liberator MK 1 AM929. Built in May 1941, during its service it drove off an FW-200 that was attacking a convoy, sighted 25 U-boats and damaged a number, sank U-597, sank U-661, sank U-132 , sank U-194, and helped to sink U-540. The best record, ever!
Shortround6
Major General
By 1944 the U-Boat war had changed drastically and not just the air component.
The surface ships were using hedgehog launchers and squid anti sub mortars. They were using much larger depth charge patterns (they started the war with a 4 charge pattern and ended with a 14 charge pattern in the ships that could carry such an load). faster sinking charges and much improved sonars, let alone improved radars on the ships.
The aircraft got better radars, leigh lights, rockets and better anti-sub bombs/depth chargers (with better explosives) plus the already mentioned homing torpedoes.
The war was far from static in regards to weapons and tactics and the actual threat of the German U-boats changed back and forth. By 1944 it was pretty much done.
A lot is made of of the B-24 and the Atlantic gap but for parts of the war the gap didn't exist for the simple reason that the Germans weren't operating in the mid atlantic.
sinkings by U-boats.
and
In Sept 1939 to Sept 1940 the sinkings were clustered around the British Isles much more than the first map shows.
The U-boats liked to operate where the prospects of success were high and risks low, so as the anti-sub efforts got better around the British Isles the U-boats traveled greater distances to operate. (that and availability of the French ports in the summer of 1940). The US slow off the mark in using convoys or getting a good anti-sub aircraft effort going, in Jan 1941 there were no anti-sub aircraft units based any further south than Virginia leaving the southern US, the Caribbean and the Gulf of Mexico pretty exposed.
Spring/summer of 1942 saw a lot of the action shifting to American waters.
Until the "coastal" or near waters are secured there was little reason to secure the "mid-atlantic"
Note the cluster of sinkings off the north coast of South America. That is where the border of Venezuela is and the refineries in Trinidad.
Once they pushed the U-boats out of the Gulf of Mexico, the Caribbean and further off the US coast then you could worry about closing the atlantic gap.
These maps were prepared by the US Army and may not be 100% accurate (sinkings in the Med and right around Britain/North sea being ignored?
In any case this history claims "By the end of January, I Bomber Command aircraft available for antisubmarine duty numbered a total of 119. Only forty-six of the aircraft could be considered in commission, but of this effective strength, nine were B-17's capable of long-range patrol, and the rest were B-18's and B-25' "
That would be Jan of 1942. and I bomber command was responsible for the entire east coast.
The surface ships were using hedgehog launchers and squid anti sub mortars. They were using much larger depth charge patterns (they started the war with a 4 charge pattern and ended with a 14 charge pattern in the ships that could carry such an load). faster sinking charges and much improved sonars, let alone improved radars on the ships.
The aircraft got better radars, leigh lights, rockets and better anti-sub bombs/depth chargers (with better explosives) plus the already mentioned homing torpedoes.
The war was far from static in regards to weapons and tactics and the actual threat of the German U-boats changed back and forth. By 1944 it was pretty much done.
A lot is made of of the B-24 and the Atlantic gap but for parts of the war the gap didn't exist for the simple reason that the Germans weren't operating in the mid atlantic.
sinkings by U-boats.
and
In Sept 1939 to Sept 1940 the sinkings were clustered around the British Isles much more than the first map shows.
The U-boats liked to operate where the prospects of success were high and risks low, so as the anti-sub efforts got better around the British Isles the U-boats traveled greater distances to operate. (that and availability of the French ports in the summer of 1940). The US slow off the mark in using convoys or getting a good anti-sub aircraft effort going, in Jan 1941 there were no anti-sub aircraft units based any further south than Virginia leaving the southern US, the Caribbean and the Gulf of Mexico pretty exposed.
Spring/summer of 1942 saw a lot of the action shifting to American waters.
Until the "coastal" or near waters are secured there was little reason to secure the "mid-atlantic"
Note the cluster of sinkings off the north coast of South America. That is where the border of Venezuela is and the refineries in Trinidad.
Once they pushed the U-boats out of the Gulf of Mexico, the Caribbean and further off the US coast then you could worry about closing the atlantic gap.
These maps were prepared by the US Army and may not be 100% accurate (sinkings in the Med and right around Britain/North sea being ignored?
In any case this history claims "By the end of January, I Bomber Command aircraft available for antisubmarine duty numbered a total of 119. Only forty-six of the aircraft could be considered in commission, but of this effective strength, nine were B-17's capable of long-range patrol, and the rest were B-18's and B-25' "
That would be Jan of 1942. and I bomber command was responsible for the entire east coast.
1939:
Allied and Neutral ship tonnage sunk by German and Italian submarines (#ships, GRT)
Sep39 48/178,621
Oct39 33/156,156
Nov39 27/72,721
Dec39 39/101,823
Tot39 147 (36.75/month)/509,321 (127,330.25/month)
British merchant ship construction capacity from 1939-1941 did not exceed 1.2 million GRT per year.
US merchant ship construction in 1939 was 0.242 million GRT.
Number of U-Boat patrols (combat patrols only, does not include tanker/resupply missions)/losses/aborts prior to contact in principle theaters (North Atlantic, South Atlantic, Indian Ocean, and the Americas)
Aug39 19/2
Sep39 3/0
Oct39 13/3
Nov39 10/1/1
Dec39 5/1/1
Tot39 50/7/2 (an average of 10 patrols per month and 14% lost)
Thus for 1939, an average of 2.94 ships were sunk per patrol and one U-Boat was lost per 21 ships sunk (note that throughout these averages will be slightly inflated since they do not include the minor contribution of the Italian submarine fleet.)
1940:
Allied and Neutral ship tonnage sunk by German and Italian submarines (#ships, GRT)
Jan40 53/163,029
Feb40 50/182,369
Mar40 26/69,826
Apr40 6/30,927
May40 14/61,635
Jun40 66/375,069
Jul40 41/301,975
Aug40 56/288,180
Sep40 60/288,180
Oct40 66/363,267
Nov40 36/181,695
Dec40 46/256,310
Tot40 520 (43.33/month)/2,462,867 (205,238.91/month)
US merchant ship construction for 1940 was about 0.5 million GRT.
Number of U-Boat patrols (combat patrols only, does not include tanker/resupply missions)/losses/aborts prior to contact in principle theaters (North Atlantic, South Atlantic, Indian Ocean, and the Americas)
Jan40 8/2
Feb40 10/3
Mar40 10/2
Apr40 19/3
May40 8/0/2
Jun40 18/3/1
Jul40 4/0
Aug40 16/2/1
Sep40 12/0
Oct40 13/2
Nov40 14/1
Dec40 6/0
Tot40 138/18/3 (an average of 11.5 patrols per month and 13% lost)
Thus for 1940, an average of 3.77 ships were sunk per patrol and one U-Boat was lost per 28.89 ships sunk.
1941:
Allied and Neutral ship tonnage sunk by German and Italian submarines (#ships, GRT)
Jan41 23/129,711
Feb41 47/254,118
Mar41 41/236,549
Apr41 41/239,719
May41 63/362,268
Jun41 66/325,817
Jul41 26/112,624
Aug41 27/85,603
Sep41 57/212,237
Oct41 28/170,786
Nov41 15/76,056
Dec41 23/93,226
Tot41 457 (38.08/month)/2,298,714 (191,559.5/month)
US merchant ship construction 1941 0.804 million GRT
Number of U-Boat patrols (combat patrols only, does not include tanker/resupply missions)/losses/aborts prior to contact in principle theaters (North Atlantic, South Atlantic, Indian Ocean, and the Americas)
Jan41 10/0
Feb41 18/3/2
Mar41 15/3/3
Apr41 14/2/2
May41 21/0/2
Jun41 22/2/3
Jul41 24/1/9
Aug41 42/5/9
Sep41 38/0/2
Oct41 37/0/6
Nov 41 27/5/5
Dec41 49/4/6
Tot 41 287/25/49 (an average of 23.9 patrols sailing per month and 8.7% lost)
Thus for 1941, an average of 1.59 ships were sunk per patrol and one U-Boat was lost per 18.28 ships sunk.
1942:
Allied and Neutral ship tonnage sunk by German and Italian submarines (#ships, GRT)
Jan42 56/310,224
Feb42 72/429,255
Mar42 93/507,514
Apr42 81/418,161
May42 129/616,835
Jun42 136/636,926
Jul42 96/467,051
Aug42 117/587,245
Sep42 96/461,794
Oct42 89/583,690
Nov42 126/802,160
Dec42 64/337,618
Tot42 1,155 (96.25/month)/6,158,473 (513,206.08/month)
British and Canadian merchant ship construction 1942 1.8 million GRT
US merchant ship construction 1942 5.433 million GRT
Number of U-Boat patrols (combat patrols only, does not include tanker/resupply missions)/losses/aborts prior to contact in principle theaters (North Atlantic, South Atlantic, Indian Ocean, and the Americas)
Jan42 50/2/5
Feb42 29/3/2
Mar42 32/2
Apr42 37/2/2
May42 23/3
Jun42 39/9/5
Jul42 45/7/3
Aug42 58/10/4
Sep42 52/8/8
Oct42 62/6/10
Nov42 54/8/6
Dec42 59/8/7
Tot42 540/68/57 (an average of 45 patrols sailing per month and 12.6% lost)
Thus for 1942, an average of 2.14 ships were sunk per patrol and one U-Boat was lost per 16.99 ships sunk.
1943:
Allied and Neutral ship tonnage sunk by German and Italian submarines (#ships, GRT)
Jan43 44/307,196
Feb43 67/362,081
Mar43 110/633,731
Apr43 50/287,137
May43 46/237,182
Jun43 17/76,090
Jul43 46/237,777
Aug43 20/92,443
Sep43 16/98,852
Oct43 20/91,295
Nov43 9/30,726
Dec43 8/55,794
Tot43 452 (37.67/month)/2,510,304 (209,192/month)
US merchant ship construction 1943 13.081 million GRT
Number of U-Boat patrols (combat patrols only, does not include tanker/resupply missions)/losses/aborts prior to contact in principle theaters (North Atlantic, South Atlantic, Indian Ocean, and the Americas)
Jan43 61/13/11
Feb43 72/8/9
Mar43 59/16/10
Apr43 95/35/18
May43 55/23/9
Jun43 46/23/9
Jul43 39/27/7 (49 total patrols of all types)
Aug43 33/12/6
Sep43 32/11/10
Oct43 62/23/9
Nov43 36/9/4
Dec43 31/10/2
Tot43 621/210/104 (an average of 51.75 patrols sailing per month and 33.8% lost)
Thus for 1943, an average of 0.73 ships were sunk per patrol and one U-Boat was lost per 2.15 ships sunk.
So, overall, the most successful year for the U-Boats was 1940, before the expansion of the force allowed for an increase of more than about a dozen patrols sailing per month, and well prior to the entry of the US and its shipbuilding capacity into the war. Worse, the performance of the U-Boat force in 1941 and 1942 never exceeded its performance in the first months of the war. And, after 1943 the U-Boat campaign became ever less relevent to the outcome of the war.
Allied and Neutral ship tonnage sunk by German and Italian submarines (#ships, GRT)
Tot44 125/663,308
Tot45 63/284,476
US merchant ship construction for 1944 was 12.257 million GRT
US merchant ship construction for 1945 (through 1 May) was 3.548 million GRT
U-Boat Fleet to 1Sep42
On 19Aug39 there were 57 U-Boats in commission, 20 sea-going U-Boats and 18 'ducks' were fully ready to put to sea
Total number U-Boats deployed to 1Sep42 275
Total number lost 94
Total number retired 10
Total number available 171
U-Boat Fleet 1Sep42 to 1May45
Total number deployed 1Sep42 to 1May45 531
Total number lost 1Sep42 to 1May45 568
British controlled merchant shipping over 1,600 GRT (number/in thousands of gross tons)
3Sep39 2,999/17,784
30Sep40 3,75721,373
30Sep41 3,608/20,552
31Dec41 3,616/20,693
Thus, despite the 'success' of the U-Boat force in 1940 (relative to its performance in 1941 and 1942) it had no appreciable effect in reducing the size of the British merchant fleet.
Numbers of ships arriving and losses in North Atlantic convoys inbound to Britain (ships arriving/losses)
1939 700/5 (.71%)
1940 5,434/133 ((2.5%)
1941 5,923/153 (2.6%)
1942 4,798/80 (1.7%)
1943 5,667/87 (1.5%)
1944 7,410/8 (0.1%)
The operational U-Boat force from 1943-1945 never approached a "steady 400-500 boat." Rather, during 1942 the peak strength of boats assigned to combat flotillas (including those under repair for combat-damage and breakdowns, but excluding those assigned to school flotillas, experimental projects, or otherwise retired from combat) was 202, during November. The low in 1942 was 89 in January. The average monthly strength during 1942 was 143.83. The strength of the force peaked in May 1943 at 237. It had declined to a low of 159 by November. Average monthly strength during 1943 was 197.58. The peak strength during 1944 was 168 in February, the low was 146 in November. Average monthly strength in 1944 was 157.83. The peak strength in 1945 was April with 165, the low was May with 134, prior to the surrender. <http://www.onwar.com/ubb/smile.gif>
At that, these were much better than 1939 (average of 19.5 monthly), 1940 (average of 18.75 monthly) and 1941 (average of 47.5 monthly). OTOH, the 'bang for their buck' was probably highest in 1940, which was also arguably the U-Boats most 'successful' year in terms of ships sunk per patrol and U-Boats lost per ship sunk (see my previous reply).
Allied and Neutral ship tonnage sunk by German and Italian submarines (#ships, GRT)
Sep39 48/178,621
Oct39 33/156,156
Nov39 27/72,721
Dec39 39/101,823
Tot39 147 (36.75/month)/509,321 (127,330.25/month)
British merchant ship construction capacity from 1939-1941 did not exceed 1.2 million GRT per year.
US merchant ship construction in 1939 was 0.242 million GRT.
Number of U-Boat patrols (combat patrols only, does not include tanker/resupply missions)/losses/aborts prior to contact in principle theaters (North Atlantic, South Atlantic, Indian Ocean, and the Americas)
Aug39 19/2
Sep39 3/0
Oct39 13/3
Nov39 10/1/1
Dec39 5/1/1
Tot39 50/7/2 (an average of 10 patrols per month and 14% lost)
Thus for 1939, an average of 2.94 ships were sunk per patrol and one U-Boat was lost per 21 ships sunk (note that throughout these averages will be slightly inflated since they do not include the minor contribution of the Italian submarine fleet.)
1940:
Allied and Neutral ship tonnage sunk by German and Italian submarines (#ships, GRT)
Jan40 53/163,029
Feb40 50/182,369
Mar40 26/69,826
Apr40 6/30,927
May40 14/61,635
Jun40 66/375,069
Jul40 41/301,975
Aug40 56/288,180
Sep40 60/288,180
Oct40 66/363,267
Nov40 36/181,695
Dec40 46/256,310
Tot40 520 (43.33/month)/2,462,867 (205,238.91/month)
US merchant ship construction for 1940 was about 0.5 million GRT.
Number of U-Boat patrols (combat patrols only, does not include tanker/resupply missions)/losses/aborts prior to contact in principle theaters (North Atlantic, South Atlantic, Indian Ocean, and the Americas)
Jan40 8/2
Feb40 10/3
Mar40 10/2
Apr40 19/3
May40 8/0/2
Jun40 18/3/1
Jul40 4/0
Aug40 16/2/1
Sep40 12/0
Oct40 13/2
Nov40 14/1
Dec40 6/0
Tot40 138/18/3 (an average of 11.5 patrols per month and 13% lost)
Thus for 1940, an average of 3.77 ships were sunk per patrol and one U-Boat was lost per 28.89 ships sunk.
1941:
Allied and Neutral ship tonnage sunk by German and Italian submarines (#ships, GRT)
Jan41 23/129,711
Feb41 47/254,118
Mar41 41/236,549
Apr41 41/239,719
May41 63/362,268
Jun41 66/325,817
Jul41 26/112,624
Aug41 27/85,603
Sep41 57/212,237
Oct41 28/170,786
Nov41 15/76,056
Dec41 23/93,226
Tot41 457 (38.08/month)/2,298,714 (191,559.5/month)
US merchant ship construction 1941 0.804 million GRT
Number of U-Boat patrols (combat patrols only, does not include tanker/resupply missions)/losses/aborts prior to contact in principle theaters (North Atlantic, South Atlantic, Indian Ocean, and the Americas)
Jan41 10/0
Feb41 18/3/2
Mar41 15/3/3
Apr41 14/2/2
May41 21/0/2
Jun41 22/2/3
Jul41 24/1/9
Aug41 42/5/9
Sep41 38/0/2
Oct41 37/0/6
Nov 41 27/5/5
Dec41 49/4/6
Tot 41 287/25/49 (an average of 23.9 patrols sailing per month and 8.7% lost)
Thus for 1941, an average of 1.59 ships were sunk per patrol and one U-Boat was lost per 18.28 ships sunk.
1942:
Allied and Neutral ship tonnage sunk by German and Italian submarines (#ships, GRT)
Jan42 56/310,224
Feb42 72/429,255
Mar42 93/507,514
Apr42 81/418,161
May42 129/616,835
Jun42 136/636,926
Jul42 96/467,051
Aug42 117/587,245
Sep42 96/461,794
Oct42 89/583,690
Nov42 126/802,160
Dec42 64/337,618
Tot42 1,155 (96.25/month)/6,158,473 (513,206.08/month)
British and Canadian merchant ship construction 1942 1.8 million GRT
US merchant ship construction 1942 5.433 million GRT
Number of U-Boat patrols (combat patrols only, does not include tanker/resupply missions)/losses/aborts prior to contact in principle theaters (North Atlantic, South Atlantic, Indian Ocean, and the Americas)
Jan42 50/2/5
Feb42 29/3/2
Mar42 32/2
Apr42 37/2/2
May42 23/3
Jun42 39/9/5
Jul42 45/7/3
Aug42 58/10/4
Sep42 52/8/8
Oct42 62/6/10
Nov42 54/8/6
Dec42 59/8/7
Tot42 540/68/57 (an average of 45 patrols sailing per month and 12.6% lost)
Thus for 1942, an average of 2.14 ships were sunk per patrol and one U-Boat was lost per 16.99 ships sunk.
1943:
Allied and Neutral ship tonnage sunk by German and Italian submarines (#ships, GRT)
Jan43 44/307,196
Feb43 67/362,081
Mar43 110/633,731
Apr43 50/287,137
May43 46/237,182
Jun43 17/76,090
Jul43 46/237,777
Aug43 20/92,443
Sep43 16/98,852
Oct43 20/91,295
Nov43 9/30,726
Dec43 8/55,794
Tot43 452 (37.67/month)/2,510,304 (209,192/month)
US merchant ship construction 1943 13.081 million GRT
Number of U-Boat patrols (combat patrols only, does not include tanker/resupply missions)/losses/aborts prior to contact in principle theaters (North Atlantic, South Atlantic, Indian Ocean, and the Americas)
Jan43 61/13/11
Feb43 72/8/9
Mar43 59/16/10
Apr43 95/35/18
May43 55/23/9
Jun43 46/23/9
Jul43 39/27/7 (49 total patrols of all types)
Aug43 33/12/6
Sep43 32/11/10
Oct43 62/23/9
Nov43 36/9/4
Dec43 31/10/2
Tot43 621/210/104 (an average of 51.75 patrols sailing per month and 33.8% lost)
Thus for 1943, an average of 0.73 ships were sunk per patrol and one U-Boat was lost per 2.15 ships sunk.
So, overall, the most successful year for the U-Boats was 1940, before the expansion of the force allowed for an increase of more than about a dozen patrols sailing per month, and well prior to the entry of the US and its shipbuilding capacity into the war. Worse, the performance of the U-Boat force in 1941 and 1942 never exceeded its performance in the first months of the war. And, after 1943 the U-Boat campaign became ever less relevent to the outcome of the war.
Allied and Neutral ship tonnage sunk by German and Italian submarines (#ships, GRT)
Tot44 125/663,308
Tot45 63/284,476
US merchant ship construction for 1944 was 12.257 million GRT
US merchant ship construction for 1945 (through 1 May) was 3.548 million GRT
U-Boat Fleet to 1Sep42
On 19Aug39 there were 57 U-Boats in commission, 20 sea-going U-Boats and 18 'ducks' were fully ready to put to sea
Total number U-Boats deployed to 1Sep42 275
Total number lost 94
Total number retired 10
Total number available 171
U-Boat Fleet 1Sep42 to 1May45
Total number deployed 1Sep42 to 1May45 531
Total number lost 1Sep42 to 1May45 568
British controlled merchant shipping over 1,600 GRT (number/in thousands of gross tons)
3Sep39 2,999/17,784
30Sep40 3,75721,373
30Sep41 3,608/20,552
31Dec41 3,616/20,693
Thus, despite the 'success' of the U-Boat force in 1940 (relative to its performance in 1941 and 1942) it had no appreciable effect in reducing the size of the British merchant fleet.
Numbers of ships arriving and losses in North Atlantic convoys inbound to Britain (ships arriving/losses)
1939 700/5 (.71%)
1940 5,434/133 ((2.5%)
1941 5,923/153 (2.6%)
1942 4,798/80 (1.7%)
1943 5,667/87 (1.5%)
1944 7,410/8 (0.1%)
The operational U-Boat force from 1943-1945 never approached a "steady 400-500 boat
At that, these were much better than 1939 (average of 19.5 monthly), 1940 (average of 18.75 monthly) and 1941 (average of 47.5 monthly). OTOH, the 'bang for their buck' was probably highest in 1940, which was also arguably the U-Boats most 'successful' year in terms of ships sunk per patrol and U-Boats lost per ship sunk (see my previous reply).
