Why Submarine Deck Guns were Eliminated on German WWII U-boats

the intent of this video is to review the major shift in World War II German submarine deck gun armaments and tactics as the war progressed this is a part 7 video from the Channel's World War II bombers versus submarine Battle of the Atlantic series during the Spring of 1943 German submarine losses due to aircraft were greater than surface ships as discussed in this May 1943 meeting minutes document between Carl dernitz Adolf Hitler and various other high-ranking German view personnel the source of these discussions is the post-war translated fewer conferences on matters dealing with the German Navy in 1943 all of the images shown in this video are Declassified this image shows dernitz inspecting u-94 while docked at the Saint nazare French port the Germans changed their U-Boat aircraft engagement policy in the spring of 1943 as defined in this April 1945 chief of the air staff intelligence historical division document the anti-submarine command in earlier engagements German U-boats would almost always dive if spotted Allied patrolling aircraft the new policy mandated that U-boats would stay on the surface and fight it out with the attacking aircraft darnitz issued standing War order 483 which instructed German U-boats traversing the Bay of Biscay to stay on the surface and fight the attacking aircraft with their anti-aircraft guns rather than submerging the Germans converted four U-boats as dedicated anti-aircraft flak platforms to act as submarine escorts much like fighter escorts for bombers the dedicated escort U-boats were fitted with additional anti-aircraft armaments as shown in this image this map represents the German U-Boat and Allied Merchant shipping losses for the month of May 1943 extracted from the anti-submarine command monthly intelligence report the blue circles are merchant ship sunk due to German submarines the red solid circles are U-Boat sunk are probably sunk due to aircraft the hollow red circles are U-boats damaged by aircraft attacks the concentrated surface engagements between Allied aircraft and U-boats in the Bay of Biscay are clearly visible on the map in this circled area there were various guns adopted by the German U-boats none of which were standard as shown in this image for men in April 1944 chief of the naval operations document German and Japanese submarines and their equipment the anti-aircraft flat guns are classified based on their caliber as shown in this image from an April 1945 sinpak bulletin Japanese anti-aircraft material Gun Barrel diameters that are above 75 millimeters are to be classified as heavy Flack Gun Barrel diameters between 20 millimeters and 40 millimeters are considered medium black the main German heavy flat guns were either the 88 millimeter or the larger 105 millimeter deck guns although the 88 millimeter U-Boat deck guns were the same caliber as the famous ground deployed 88 millimeter gun they were different and did not have interchangeable cartridges the U-boats large caliber 88 or 105 millimeter heavy flat guns were rarely used against aircraft the heavy caliber deck guns are considered ineffective against attacking aircraft as a projectile's fuse cannot be set below 5000 feet as discussed in this June 1943 anti-submarine command monthly intelligence report this would require an unlucky Direct Hit the report goes on describing other factors of the 88 105 millimeter deck guns as being manually directed and operated having a slow rate of fire and difficult to train and fire upon a fast and low-flying aircraft German nubo pows indicated they received inadequate anti-aircraft training which contributed to the ineffective anti-aircraft fire the submarine's heavy caliber deck guns are used for C2C engagements and not effective for C2 air engagements this chart outlines the various parameters of the 88 millimeter and 105 millimeter German U-Boat large caliber deck guns including the type of shell rate of fire muzzle speed max range practical range shell weight fuse type number of rounds and the quantity of ammo carry early War German U-boats were generally armed with a single heavy caliber deck gun and one or two medium caliber anti-aircraft guns the Armament of Submarine ubunt62 consisted of a single 105 millimeter heavy gun a single medium plaque 37 millimeter gun and a single 20 millimeter flat gun as described in this report of interrogations of survivors from u162 sunk on September 3rd 1942 the pow stated that this was a standard layout for a 750 ton class U-boat the sole survivor from the sinking of you 512 in October 1942 indicated that its Armament was the same layout as u-162s u-701 carried a single 88 millimeter and a single 20 millimeter gun u164's Armament consisted of a single 10.5 centimeter gun a single 37 millimeter gun and a single 20 millimeter gun for anti-aircraft attacks the pow stated that 20 millimeter was not trusted four mg34 machine guns were also carried the mg34's ammo is in the 7.92 millimeter light machine gun cartridge machine guns and various calibers would be mounted on the conning Tower like in this view this image u-564 and this view of u760. by mid-1943 most of the U-boats large caliber deck guns were removed this was due to little or no opportunity to use the deck guns to attack unprotected Allied ships or aircraft without great risk as shown in this image conboys were well protected surfacing to fire the deck guns would be considered suicide the large caliber deck guns could be replaced with the more effective 37 millimeter anti-aircraft guns as shown in this sketch to Genesis for more effective U-Boat anti-aircraft Armament can be traced to the September 1942 reich's chancellery conference meeting minutes as shown in this document German rear Admiral Lang recommended 15 millimeter anti-aircraft guns be fitted to U-Boat conning Towers Adolf Hitler considered the 15 millimeter guns not effective enough against Allied bombers the upsized 20 millimeter cannons were discussed it was also recommended that 3.7 centimeter and five centimeter anti-aircraft guns be fitted to you boats Adolf Hitler indicated misgivings of the five centimeter guns due to Air Force experiences neither the 15th millimeter nor the five centimeter guns were ever fitted to German U-boats pows from the sinking of u67 in July of 1943 indicated that multiple U-boats have been fitted with two quadrupole 20 millimeter and a single 37 millimeter flat gun the addition of quadruple 20 millimeter anti-aircraft batteries to you boats was discussed in the May 1943 German Navy meeting minutes conning Towers were rebuilt to mount the new armaments these black U-boats are to remain on the surface and fight it out with aircraft traversing submarines would be met and escorted by an anti-aircraft submarine u-67 would dive if an Allied aircraft was cited by binoculars if an aircraft was cited by the naked eye they would remain on the surface and fight back this chart outlines various parameters for the 20 and 37 millimeter anti-aircraft black guns the rows indicate the type of guns as quad twin or single Mount 20 millimeter or 37 millimeter single cannons The Columns are the guns parameters as discussed earlier this chart lists additional parameters including the gun's Arc travel and the number of crew members assigned only the U-boats anti-aircraft guns included armor plates to protect the crew members as discussed on this chart from the Armament section of the reference shown earlier the 20 millimeter quadruple gun crews are protected by armor plates ranging from 5 to 15 millimeters in thickness the 37 millimeter gun crews are protected by armor plates ranging from 15 to 20 millimeters in gauge two 20 millimeter dual guns and a single 37 millimeter anti-aircraft gun is shown in this side and top view image the 20 millimeter single dual or quadruple mountings are the u-boat's main anti-aircraft Armament they are considered very effective except against heavy bombers the 37 millimeter anti-aircraft gun can be readied in three minutes and secured for diving in one minute so let's take a look at U-boats with modified anti-aircraft armaments this image shows a mounted at 37 millimeter cannon with armor this image shows a U-Boat with its 88 millimeter deck gun replaced with a 37 millimeter anti-aircraft gun use 744 with two dual 20 millimeter and a single 37 millimeter gun 37 millimeter gun with armored plate stowed u-1023 with two dual 20 millimeter and a single 37 millimeter cannon u-103 unarmored deck gun illustration of a single 37 millimeter and two single 20 millimeter guns u-889's 37 millimeter twins with armor stowed only a few U-boats were fitted with dual 37 millimeter Armament the U-Boat is also fitted with two dual 20 millimeter flat cannons notice this U-Boat doesn't have a heavy deck gun dual 20 millimeter flat guns the conning Tower is located here the two dual 20 millimeter anti-aircraft flat guns are mounted on the AFT Bridge platform the twin 37 millimeter anti-aircraft flat guns are mounted on the Winter Garden platform curation is represented by both u889 and u995 the Winter Garden deck platform level is shown in this view u-745's quadrupole 20 millimeter flat guns with deployed armor panels is in this image side view of one of the four built Flac escort U-boats front view of the quadruple 20 millimeter flat guns with armor side view of the quadruple 20 millimeter flat guns with armor rear view of the quadruple 20 millimeter flat guns with armor U.S boarding party capturing U-505 on June 4th 1944. note that it is not outfitted with a heavy deck gun U-505 getting ready for delivery at the Chicago Museum of Science and Industry with a standard single 37 millimeter and two twin 20 millimeter anti-aircraft armaments to counter the new U-Boat anti-aircraft armaments and fight back tactics Allied aircraft were provided guidance as discussed in this image from a May 1943 anti-submarine monthly intelligence report the choice to engage the U-Boat or not rests with the aircraft Commander he must take into account his tactical position relative to the submarine the aircraft Commander is reminded of his primary mission that is to destroy submarines aircraft are difficult targets for the U-Boat Gunners U-boats are poor gun platforms attack the U-Boat head on and weave fire the plane's machine guns at the U-Boat gun Crews or suppressor returning fire the point regarding attacking the U-Boat head-on is discussed in the countermeasure section of the June 1943 anti-submarine command monthly intelligence report most of the anti-aircraft guns on a submarine are mounted aft of the conning Tower the conning Tower will block guns aimed forward at a low-flying aircraft so how effective was a German U-Boat fightback policy and the added anti-aircraft armaments the German Navy evaluated the combat effectiveness of the U-boats 20 millimeter anti-aircraft guns in this July 31st 1943 Navy meeting minutes planes were not brought down by multiple hits from the U-boats 20 millimeter quad guns this image from an August 1943 anti-submarine command monthly intelligence report outlines the results of 25 engagements between aircraft and U-boats that remain on the surface and fought back during August of 1943. six submarines were sunk at the cost of nine aircraft destroyed an additional nine aircraft damaged bummer command recognized The Valor showed regardless of the Peril they faced while the fight back policy was in effect a little over three months for May 1943 through mid-august 1943 Allied aircraft sank 26 U-boats and damaged another 17 for a loss of 32 aircraft the U-Boat loss rate was unattainable and the fight back order was rescinded and in retrospect a failure if you've enjoyed this video please consider commenting liking or subscribing to the Channel World War II U.S bombers

Channel: WWII US Bombers

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Id: 6pM-c8ASHFo

Length: 13min 41sec (821 seconds)

Published: Fri Apr 14 2023