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{{short description|1945 US Navy operation in the North Atlantic}}
{{Infobox military conflict
 |conflict    = Operation Teardrop
 |partof      = the [[Battle of the Atlantic|Atlantic Campaign]] of [[World War II]]
 |image       = U-546 survivors.jpg
 |image_size  = 300
 |alt         = An inflatable raft on the water with four camouflaged World War II-era warships behind it. No land is visible.
 |caption     = A life raft carrying {{GS|U-546||2}} survivors in the midst of {{nowrap|U.S. Navy}} destroyer escorts on April 24, 1945
 |date        = April–May 1945
 |place       = [[Atlantic Ocean|North Atlantic Ocean]]
 |result      = Allied victory
 |combatant1  = {{flagu|Nazi Germany}}
 |combatant2  = {{ubl|{{flagu|United States|1912}}|{{flagu|Canada|1921}}}}
 |commander1  = {{flagd|Nazi Germany|naval}} [[Eberhard Godt]]
 |commander2  = {{flagd|USA|1912}} [[Jonas H. Ingram]]
 |strength1   = 7 submarines
 |strength2   = {{ubl|42 destroyers|4 escort carriers}}
 |casualties1 = {{ubl|'''Casualties:'''|218 killed|33 captured{{sfn|Blair|1998|p=688}}|'''Losses:'''|5 submarines sunk}}
 |casualties2 = {{ubl|'''Casualties:'''|126 killed|&nbsp;|'''Losses:'''|1 destroyer sunk}}
 |campaignbox = {{Campaignbox Atlantic Campaign}}
}}

'''Operation Teardrop''' was a [[United States Navy]] operation during [[World War II]], conducted between April and May 1945, to sink German [[U-boat]]s approaching the [[East Coast of the United States|Eastern Seaboard]] that were believed to be armed with [[V-1 flying bomb]]s. Germany had threatened to attack New York with V-1 flying bombs and [[rocket U-boat]]s. After the war, it was determined the submarines had not been carrying either.

Operation Teardrop was planned during late 1944 in response to intelligence reports which indicated that Germany was preparing a force of missile-armed submarines. Two large U.S. Navy [[anti-submarine warfare]] task forces were set up. The plan was executed in April 1945 after several [[German Type IX submarine|Type IX submarines]] put to sea from Norway bound for North America. While severe weather conditions in the [[Atlantic Ocean|North Atlantic Ocean]] greatly reduced the effectiveness of the four U.S. Navy [[escort carrier]]s involved, long patrol lines of [[destroyer escort]]s detected and engaged most of the German submarines. Aircraft of the [[Royal Canadian Air Force]] supported this effort.

Five of the seven submarines in the group stationed off the United States were sunk, four with their entire crews. Thirty-three crew members from {{GS|U-546||2}} were captured, and specialists among them were interrogated under torture. One destroyer escort was sunk, USS Frederick C. Davis (DE-136), with the loss of most of her crew. The survivors were pulled from the water within three hours, including Richard "Ray" Raymond Nowicke. The war ended shortly afterwards and all surviving U-boats surrendered. Interrogation of their crews found that missile launching equipment was never fitted to the U-boats, which was further confirmed after the war.

== Background ==
In late 1944, the [[Allies of World War II|Allies]] received intelligence reports which suggested that Germany's ''[[Kriegsmarine]]'' was planning to use {{nowrap|V-1 flying bombs}} launched from submarines to attack cities on the east coast of the United States. In September of that year, Oskar Mantel, a spy captured by the U.S. Navy when the submarine ([[German submarine U-1229|''U-1229'']]) transporting  him to [[Maine]] was sunk, told his [[FBI]] interrogators that several missile-equipped U-boats were being readied. [[United States Tenth Fleet]] analysts subsequently examined photos of unusual mountings on U-boats at [[German U-boat bases in occupied Norway|bases in Norway]], but concluded that they were wooden tracks used to load torpedoes. Further rumors of missile-armed submarines emerged later that year, including one from Sweden passed on by the [[Supreme Headquarters Allied Expeditionary Force]]. The [[British Admiralty]] discounted these reports, and assessed that while V-1s could be potentially mounted on Type IX submarines, the Germans were unlikely to devote scarce resources to such a project.{{sfn|Lundeberg|1994|pp=213–215}}

[[File:Duxford UK Feb2005 V1flyingbomb.JPG|thumb|upright=1.4|alt=A grey rocket on a camouflaged ramp in front of a hedge. The tops of houses and street lights are visible behind the hedge.|V-1 at [[Imperial War Museum Duxford]]]]

Despite the Tenth Fleet and Admiralty assessments, the U.S. military and government remained concerned that Germany would conduct vengeance attacks against East Coast cities. In early November 1944, the [[Eastern Sea Frontier]] mounted an intensive search for submarines within {{convert|250|mi|km|sp=us}} of New York City.{{sfn|Siegel|1989|p=33}} In late December 1944, the spies [[William Colepaugh|William Curtis Colepaugh]] and [[Erich Gimpel]], who had been captured in New York City after being landed by {{GS|U-1230||2}} in Maine, told their interrogators that Germany was preparing a group of rocket-equipped submarines. On 10 December, the [[Mayor of New York City]], [[Fiorello La Guardia]], publicly warned that Germany was considering an attack on New York with long-range rockets. La Guardia's warning and the claims made by the captured spies received considerable media coverage.{{sfn|Lundeberg|1994|p=215}} Despite this, the [[United States Department of War|Department of War]], which was dominated by the [[United States Army]], advised President [[Franklin D. Roosevelt]] on 11&nbsp;December that the threat of missile attack was so low that it did not justify the diversion of resources from other tasks. This assessment was not supported by the U.S. Navy.{{sfn|Siegel|1989|p=33}}

In response to the perceived threat, the [[United States Fleet Forces Command|U.S. Atlantic Fleet]] prepared a plan to defend the east coast from attacks by aerial raiders and missiles. This plan was originally code-named Operation Bumblebee, and later renamed Operation Teardrop. Completed on 6 January 1945, the plan involved U.S. Navy anti-submarine forces as well as [[United States Army Air Forces]] and Army units, which were responsible for shooting down attacking aircraft and missiles. The centerpiece of the plan was the formation of two large naval task forces to operate in the mid-Atlantic as a barrier against submarines approaching the east coast. These task forces were formed from several existing escort carrier groups, and used [[Naval Station Argentia|Naval Station Argentia, Newfoundland]], as their forward operating base. As well as guarding against missile attacks, these large forces were tasked with countering the new and high-performance [[Type XXI submarine]]s if they began operating in the central Atlantic. The Atlantic Fleet's commander, Vice Admiral [[Jonas H. Ingram]], gave a press conference on 8 January in which he warned there was a threat of missile attack and announced that a large force had been assembled to counter seaborne missile launchers.{{sfn|Lundeberg|1994|pp=215–216}}

In January 1945, German Minister of Armaments and War Production [[Albert Speer]] made a propaganda broadcast in which he claimed that V-1 and V-2s "would fall on New York by February 1, 1945", increasing the U.S. Government's concern over the threat of attack.{{sfn|Blair|1998|p=683}} However, the Germans had no ability to fire missiles from their submarines, as both attempts to develop submarine-launched rockets ended in failure. In June 1942, {{GS|U-511||2}} was used to trial small and short-ranged artillery rockets which could be fired while submerged. Development of this system ended in early 1943, as it was found to decrease the U-boats' seaworthiness.{{sfn|Lundeberg|1994|pp=213–214}} The German military also began the development of a U-boat-towed launch canister for the [[V-2]] ballistic missile in November 1944. Once complete, these canisters were to be towed to a position off the United States east coast and be used to attack New York. Vulkan Docks in [[Stettin]] was contracted to build a prototype in March or April 1945, but little work took place before Germany's final collapse. It is unlikely that the system would have been successful if it had been completed.{{sfn|Neufeld|1995|p=255}}

== Battle ==

=== Initial deployments ===
[[File:USS Croatan USN photo.jpg|thumb|alt=A World War II-era aircraft carrier at anchor. Several aircraft are on her flight deck and land and buildings are visible in the background.|{{USS|Croatan|CVE-25|2}} anchored off New York City in October 1945]]
Nine Type IX U-boats were dispatched from Norway to patrol off Canada and the United States in March 1945 and attack shipping. The purpose of this deployment was to divert Allied anti-submarine forces away from the coastal waters of the United Kingdom. These waters were the main operational area for German submarines in early 1945, but heavy casualties had forced the German navy to break off operations in late March.{{sfn|Hinsley|Ransom|Knight||1988|pp=625–626}} On 12 April, {{GS|U-518||2}}, {{GS|U-546||2}}, {{GS|U-805||2}}, {{GS|U-858||2}}, {{GS|U-880||2}}, {{GS|U-881||2}} and {{GS|U-1235||2}} were designated "''[[Wolf pack Seewolf|Gruppe Seewolf]]''" ("Group Seawolf") and ordered to attack shipping from New York southwards. The remaining two boats, {{GS|U-530||2}} and {{GS|U-548||2}}, were directed to Canadian waters.{{sfn|Blair|1998|pp=686–687}}

The Allies were aware of this force's departure and destination through information gathered from [[Enigma machine|Enigma]] decrypts. Vice Admiral Ingram and the U.S. Tenth Fleet concluded that the boats in Group Seewolf were carrying V-1s and launched ''Teardrop'' in response.{{sfn|Blair|1998|p=686}} The ships of the First Barrier Force, which comprised [[escort carrier]]s {{USS|Mission Bay|CVE-59|6}} and {{USS|Croatan|CVE-25|2}} and 20 destroyer escorts, sortied from [[Hampton Roads]] between 25 and 27 March, proceeded to Argentia to refuel and assembled east of [[Cape Race]] on 11 April. Twelve of the destroyer escorts deployed into a line {{convert|120|mi}} long while the two carriers, each protected by four destroyer escorts, sailed to the west of the line. The carriers' air operations were, however, greatly hindered by heavy seas.{{sfn|Lundeberg|1994|p=216}} The rough weather also forced the cancellation of planned memorial services for President Roosevelt after his death on 12 April.{{sfn|Morison|1956|p=346}}

As it sailed west, Group Seewolf was ordered to attack shipping by [[Befehlshaber der U-Boote|U-boat Command]]. The boats found no targets, however, as the Allies had routed convoys to the south to avoid the submarines and severe weather.{{sfn|Blair|1998|p=686}} The German submarines began to reach their initial stations east of the [[Grand Banks of Newfoundland]] on 8 April. U-boat Command assigned Group Seewolf 12 different scouting lines between 2 and 19 April. The radio signals directing these deployments were decrypted by the Allies, providing them with accurate information on where the boats were operating.{{sfn|Lundeberg|1994|p=217}}

=== First Barrier Force actions ===
Just before midnight on 15 April, {{USS|Stanton|DE-247|6}} made radar contact with ''U-1235'' at a position about {{convert|500|mi}} north of [[Flores Island (Azores)|Flores Island]]. She immediately attacked the submarine with her [[Hedgehog (weapon)|Hedgehog anti-submarine mortar]], but the submarine submerged and escaped. Assisted by {{USS|Frost|DE-144|6}}, ''Stanton'' quickly gained sonar contact with the submarine and made three more Hedgehog attacks. The third attack, which was conducted at 00:33 on 16 April, sank the submarine with the loss of her entire crew. Shortly afterwards ''Frost'' detected ''U-880'' by radar as she attempted to flee the area on the surface. After illuminating the submarine with [[Shell (projectile)#Illumination|star shell]] and spotlights, the destroyer escort opened fire on her with [[Bofors 40 mm Automatic Gun L/60|Bofors 40 mm]] guns from a range of {{convert|650|yd}} at 02:09. ''U-880'' quickly submerged but was tracked by ''Stanton''{{'}}s and ''Frost''{{'}}s sonar operators. The two American ships made several Hedgehog attacks on the submarine, with ''Stanton'' sinking her with no survivors at 04:04.{{sfn|Lundeberg|1994|p=218}} Both submarines suffered huge explosions after being struck by Hedgehog projectiles. This further raised the fear that they were carrying rockets and motivated the First Barrier Force to intensify its efforts to destroy the remaining U-boats.{{sfn|Morison|1956|p=349}}

The First Barrier Force maneuvered south westward following the destruction of ''U-1235'' and ''U-880''. [[Leigh Light]]-equipped [[Consolidated B-24 Liberator|Consolidated B-24 Liberators]] from [[VP-26|VPB-114]] spotted ''U-805'' on the surface during the nights of 18–19 April. The submarine was only {{convert|50|nmi|km}} from ''Mission Bay'' and her escorts, but was not attacked as the aircraft could not confirm whether she was hostile before she submerged. On the night of 20 April, ''U-546'' attempted to torpedo a U.S. destroyer escort, but missed. The following night, ''U-805'' was detected by {{USS|Mosley|DE-321|6}}, but escaped after being depth charged by ''Mosley'', {{USS|Lowe|DE-325|2}} and {{USS|J.R.Y. Blakely|DE-140|2}} for two hours.{{sfn|Lundeberg|1994|p=219}}

The First Barrier Force scored its final success on the night of 21–22 April. Just before midnight, {{USS|Carter|DE-112|6}} detected ''U-518'' with sonar. {{USS|Neal A. Scott|DE-769|6}} joined her and made the initial Hedgehog attack on the submarine. Following this, ''Carter'' made her own Hedgehog run, which sank ''U-518'' with no survivors.{{sfn|Lundeberg|1994|pp=219–220}} By this time, the First Barrier Force was returning to Argentia, after the Second Barrier Force had relieved it.{{sfn|Lundeberg|1994|p=220}}

Even though ''Teardrop'' was undertaken in the part of the North Atlantic for which Canada had primary responsibility, Ingram did not seek assistance from the [[Royal Canadian Navy]] (RCN) at any stage of the engagement. Moreover, Ingram did not provide the Canadian military with a situation report until after the sinking of ''U-518''. However, aircraft of the [[Royal Canadian Air Force]] (RCAF) flew offensive patrols in support of the American effort, and the RCN and RCAF intensified their patrols of inshore waters around [[Halifax, Nova Scotia|Halifax]].{{sfn|Douglas|Sarty|Whitby||2007|pp=447–448}}

=== Second Barrier Force actions ===
The Second Barrier Force comprised escort carriers {{USS|Bogue|CVE-9|6}} and {{USS|Core|CVE-13|2}} and 22 destroyer escorts. ''Bogue'' and 10 destroyer escorts had sailed from [[Quonset Point|Quonset]] on 16 April, while ''Core'' and 12 destroyer escorts sailed from [[Bermuda]] and other locations.{{sfn|Morison|1956|p=350}} The force was initially stationed along the [[45th meridian west|45th meridian]] in a patrol line {{convert|105|mi}} long, and sailed towards the east.{{sfn|Lundeberg|1994|p=220}} This line was made up of 14 destroyer escorts sailing at {{convert |5|mi|km|abbr=on}} intervals, with ''Core'' and her four escorts at its northern end and ''Bogue'' and her four escorts at the southern end.{{sfn|Morison|1956|p=350}}

On the night of 22–23 April, U-boat Command dissolved Group ''Seewolf'' and directed the three surviving boats to take up stations between New York and Halifax. Shortly afterwards, {{GS|U-881||2}}, and {{GS|U-889||2}}, which had been operating separately, were also ordered to positions between New York and [[Cape Hatteras]]. Radio signals directing these deployments were decrypted by Allied code breakers and increased fears that the submarines were trying to attack American cities.{{sfn|Lundeberg|1994|p=220}}

The Second Barrier Force encountered its first U-boat on 23 April when a [[Grumman TBF Avenger]] from VC-19 sighted ''U-881'' about {{convert|74|nmi|km}} north west of ''Bogue'' just after noon. The aircraft dropped depth charges but did not seriously damage the submarine. This was the first attack made by an aircraft during ''Teardrop''.{{sfn|Morison|1956|p=351}}

[[File:Capt Just USS Bogue.jpg|thumb|upright=1.1|alt=A bearded man wearing a white jumper walking towards the camera along a narrow walkway while holding on a railing. Water is visible below the walkway and a large number of men wearing dark clothes are either passing in the opposite way or watching the bearded man.|''Kapitänleutnant'' Just aboard ''Bogue'']]

The next day, {{GS|U-546||2}} sighted ''Core'' and maneuvered to attack the escort carrier.{{sfn|Blair|1998|p=687}} She attempted to pass through the barrier line but was detected by {{USS|Frederick C. Davis|DE-136|6}} at 08:30, which immediately prepared to attack the submarine.<ref>{{Cite web|title=H-047-1: The Last Battle of the Atlantic—Operation Teardrop|url=https://www.history.navy.mil/content/history/nhhc/about-us/leadership/director/directors-corner/h-grams/h-gram-047/h-047-1.html|access-date=2020-12-27|website=Naval History and Heritage Command|language=en-US}}</ref> After realizing that his boat had been detected ''U-546''{{'}}s commander, ''[[Kapitänleutnant]]'' Paul Just, fired a [[G7es torpedo|T-5 acoustic torpedo]] at the destroyer escort from a range of {{convert|650|yd|m}}. ''Frederick C. Davis''{{'}} [[Foxer|Foxer decoy]] was not effective, and the torpedo struck her forward engine room at 0835. She sank five minutes later with the loss of 126 of her 192 crewmen.{{Sfn|Morison|1956|p=351}}{{sfn|Lundeberg|1994|pp=221–222}} Eight American destroyer escorts subsequently [[USS Neunzer (DE-150)#Battling German submarine U-546|hunted ''U-546'']] for almost 10 hours, before {{USS|Flaherty|DE-135|6}} severely damaged her with a Hedgehog salvo. The submarine immediately surfaced but sank after ''Flaherty'' and three or four other destroyer escorts fired at it. ''Kapitänleutnant'' Just and 32 other crewmen survived the sinking and were taken prisoner.{{sfn|Blair|1998|p=687}}

Some of ''U-546''{{'}}s survivors were harshly treated in an attempt to force them to divulge whether the submarines bound for the U.S. east coast were carrying missiles. After brief interviews on board ''Bogue'', the survivors were transferred to the U.S. base at Argentia. Upon arrival on 27 April, the prisoners were screened for interrogation, with eight specialists being separated from the other 25 survivors, who were then sent to [[prisoner of war]] camps. The specialists were held in solitary confinement and subjected to "shock interrogation" techniques, exhausting physical exercise and beatings. On 30 April, ''Kapitänleutnant'' Just provided brief information on Group Seewolf's composition and mission following a second interview in which he collapsed unconscious. The information provided by Just and the other specialists did not mention whether the submarines were equipped with missiles. The eight men were transferred to [[Fort Hunt, Virginia]] shortly after [[Victory in Europe Day|VE Day]], where they continued to be harshly treated until Just agreed to write an account of ''U-546''{{'}}s history on 12 May.{{sfn|Lundeberg|1994|pp=224–225}} Historian [[Philip K. Lundeberg]] has written that the beating and torture of ''U-546''{{'}}s survivors was a "singular atrocity" motivated by the interrogators' need to promptly extract information on potential missile attacks.{{sfn|Blair|1998|p=687}}

The Second Barrier Force slowly moved south west from 24 April, searching for the remaining U-boats. {{USS|Swenning|DE-394|6}} made radar contact with a submarine on the night of 24 April, but it escaped during the resulting search. After a week of searching south of the Newfoundland Banks, the barrier force was split on 2 May to provide greater depth. The ''Mission Bay'' group reinforced the Second Barrier Force during this period, bringing its strength to three escort carriers and 31 destroyer escorts.{{sfn|Lundeberg|1994|pp=225–226}}

''U-881'' became the fifth and final U-boat to be sunk during ''Teardrop'' on 5 May. The boat was detected while attempting to pass submerged through the barrier line by {{USS|Farquhar|DE-139|6}} shortly before daybreak. The destroyer escort immediately turned to starboard and dropped depth charges, which sank the submarine with no survivors at 0616. ''U-881'' was the last German submarine to be sunk by the U.S. Navy during World War II.{{sfn|Lundeberg|1994|p=226}}

The Second Barrier Force established its final barrier line along the [[60th meridian west|60th meridian]] on 7 May. Following the [[end of World War II in Europe]] that day, it accepted the surrender of {{GS|U-234||2}}, ''U-805'', ''U-858'' and {{GS|U-1228||2}} at sea before returning to bases on the U.S. east coast.{{sfn|Y'Blood|2004|p=272}}

== Aftermath ==
[[File:USS Cusk;0834807.jpg|thumb|250px|alt=A rocket taking off horizontally from the deck of a surfaced World War II-era submarine|A "Loon" is fired from {{USS|Cusk|SS-348|2}} in 1951]]
After the German surrender the U.S. Navy continued its efforts to determine whether the U-boats had carried missiles. The crews of ''U-805'' and ''U-858'' were interrogated and confirmed that their boats were not fitted with missile launching equipment.{{sfn|Lundeberg|1994|p=227}} ''Kapitänleutnant'' Fritz Steinhoff, who had commanded ''U-511'' during her rocket trials and was captured at sea when he surrendered {{GS|U-873||2}}, was subjected to an abusive interrogation at Portsmouth by the interviewers of ''U-546''{{'}}s crew. An official Navy investigation was held into this interrogation after Steinhoff committed suicide at [[Charles Street Jail]] in [[Boston]] shortly afterwards.<ref>{{Cite journal|last=Lundeberg|first=Philip K. |url=http://www.ijnhonline.org/the-treatment-of-survivors-and-prisoners-of-war-at-sea-and-ashore/|title=The Treatment of Survivors and Prisoners of War, at Sea and Ashore|journal= International Journal of Naval History |year=2016|issue=1|volume=16}}</ref> It is not known if the Allies were aware of Steinhoff's involvement in the rocket trials.{{sfn|Lundeberg|1994|p=227}}{{sfn|Blair|1998|pp=689–690}}

The tactics used in ''Teardrop'' were evaluated by U.S. Navy officers after the war. The escort carriers' air wings were disappointed with their experience, as their ability to detect submarines was hampered by severe weather throughout the operation. Despite this, the aircraft were successful in forcing the U-boats to remain submerged, thereby greatly slowing their speed.{{sfn|Lundeberg|1994|p=227}} Other after action reports stressed the importance of teamwork between destroyer escorts when attacking submarines and argued that single barrier lines such as those used throughout most of ''Teardrop'' were inferior to grouping ships in assigned patrol areas.{{sfn|Lundeberg|1994|p=229}} Nevertheless, Philip K. Lundeberg has assessed the operation as "a classic demonstration not only of coordinated hunter tactics, derived in part from British experience, but also of the profound impact of communications intelligence in the interdiction of U-boat transit and operating areas."{{sfn|Lundeberg|1994|p=230}} Similarly, the British official history of the role intelligence played in World War II noted that information obtained from decrypted German radio transmissions contributed to "virtually all" of the sinkings during ''Teardrop''.{{sfn|Hinsley|Ransom|Knight||1988|p=626}}

A variant of the V-1 was used by the U.S. Navy to test the feasibility of launching missiles from submarines in the years after World War II. [[Republic‐Ford JB‐2]] "Loon" missiles were launched from {{USS|Cusk|SS-348|6}} and {{USS|Carbonero|SS-337|6}} in a series of tests which began on February 12, 1947. These tests were successful, and led to the development of further [[submarine-launched cruise missiles]].{{sfn|Polmar|Moore|2004|p=87}} The U.S. Navy's success in adapting a variant of the V-1 to be launched from submarines also demonstrated that it would have been technically feasible for the German navy to have done the same.{{sfn|Duffy|2004|p=72}}

== References ==

=== Footnotes ===
{{reflist|20em}}

=== Sources ===
{{refbegin}}
* {{cite book|last=Blair|first=Clay|title=Hitler's U-Boat War. The Hunted, 1942–1945| publisher=Random House|location=New York|year= 1998| edition= Modern Library | isbn = 0-679-64033-9 }}
* {{cite book|last1=Douglas|first1=W. A. B.|last2=Sarty|first2=Roger|last3=Whitby|first3=Michael|title=A Blue Water Navy: The Official Operational History of the Royal Canadian Navy in the Second World War, 1943–1945. Volume II, Part 2|year=2007|publisher=Vanwell Publishing|location=St. Catherine's, Canada|isbn=978-1-55125-069-4 }}
* {{cite book|last=Duffy|first=James P.|title= Target America: Hitler's plan to attack the United States|publisher= Greenwood |year= 2004|location = Santa Barbara | isbn = 0-275-96684-4|url=https://books.google.com/books?id=hrsi2rH28NQC }}
* {{cite book|last1= Hinsley|first1= F. H. |title= British Intelligence in the Second World War : Its Influence on Strategy and Operations. Volume Three, Part II| year = 1988 | publisher=Her Majesty's Stationery Office|location=London|isbn=0-11-630940-7|last2=Ransom|first2=C. F. G.|last3=Knight|first3=R. C. }}
* {{cite book|last=Lundeberg|first= Philip K.|title= To Die Gallantly : The Battle of the Atlantic| editor= Runyan, Timothy J. |editor2=Copes, Jan M|publisher= Westview Press | location=Boulder|year=1994| chapter=Operation Teardrop Revisited|isbn=0-8133-8815-5 }}
* {{cite book|last=Morison|first=Samuel Eliot|title=The Atlantic Battle Won May 1943— May 1945| publisher=Castle Books|location=Edison|orig-year= 1956|year= 2001 | edition =Castle Books|series=[[History of United States Naval Operations in World War II|History of United States Naval Operations in World War II, Vol. 10]]| isbn = 0-7858-1311-X | ref = {{SfnRef|Morison|1956}} }}
* {{cite book|last=Neufeld|first=Michael J.|title=The Rocket and the Reich. Peenemünde and the Coming of the Ballistic Missile Era|publisher=The Free Press|location=New York|year=1995|isbn=0-02-922895-6|url-access=registration|url=https://archive.org/details/isbn_9780029228951}}
* {{cite book|last1 =Polmar|first1 =Norman| last2 =Moore | first2 = Kenneth J.|title=Cold War submarines: the design and construction of U.S. and Soviet submarines | publisher= Brassey's|year=2004|edition= Illustrated|isbn=1-57488-594-4|location=Herndon|url=https://books.google.com/books?id=cP4KPxaB8DQC }}
* {{cite web|url=http://ibiblio.org/hyperwar/NHC/Capstone/WartimeDiversionNavyForcesCoastalDefense/WartimeDiversionNavyForcesCoastalDefense.html|title=The Wartime Diversion of U.S. Navy Forces in Response to Public Demands for Augmented Coastal Defense|last=Siegel|first= Adam B.|year= 1989|publisher= HyperWar Project | access-date = May 10, 2013 }}
* {{cite book|last=Y'Blood|first=William T.|title=Hunter-killer: U.S. escort carriers in the Battle of the Atlantic|publisher= Naval Institute Press|year= 2004 | edition = illustrated |isbn=1-59114-995-9| location=Annapolis|url=https://books.google.com/books?id=GKfJDaDX3yUC }}
{{refend}}

== External links ==
{{Commons category|Operation Teardrop}}
* {{cite web|url=http://www.uboatarchive.net/U-546.htm|title=U-546 sunk by aircraft from USS Bogue and Core and numerous destroyer escorts on April 25, 1945|work=U-boat Archive|url-status=dead|archive-url=https://web.archive.org/web/20090905150207/http://www.uboatarchive.net/U-546.htm|archive-date=September 5, 2009}}

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[[Category:Conflicts in 1945]]
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