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{{short description|Naval artillery mounted on the deck of a submarine}}
{{About||a type of large water nozzle used for firefighting|Fire monitor}}
{{Expand Russian|topic=tech|fa=yes|date=February 2013|Артиллерия подводных лодок}}
{{Use dmy dates|date=December 2020}}
[[File:HN-British-4-inch-submarine-gun-3.jpg|thumb|right|British [[QF 4 inch naval gun Mk IV, XII, XXII|Mk XXII 4-inch deck gun]] from [[British S-class submarine (1931)|S-class submarine]]]]
[[File:5 inch 25 caliber gun USS Bowfin.jpg|thumb|right|[[5"/25 caliber gun]] on the deck of {{sclass|Balao|submarine|1}} {{USS|Bowfin|SS-287|6}}]]
[[File:102 mm Bofors naval gun.jpg|thumb|right|Bofors 102 mm/4-inch naval gun from the Romanian submarine {{ship|NMS|Delfinul||2}}]]

A '''deck gun''' is a type of [[naval artillery]] mounted on the deck of a [[submarine]]. Most submarine deck guns were open, with or without a shield; however, a few larger submarines placed these guns in a [[gun turret|turret]].{{citation needed|date=January 2022}}

The main deck gun was a dual-purpose weapon used to sink merchant shipping or shell shore targets, or defend the submarine on the surface from enemy aircraft and warships. Typically a crew of three operated the gun, while others were tasked with supplying ammunition. A small [[Locker|locker box]] held a few 'ready-use' rounds. With a well-drilled, experienced crew, the rate of fire of a deck gun could be 15 to 18 aimed shots per minute.

Some submarines also had additional deck guns like auto-cannons and machine guns for anti-aircraft defense.

While similar unenclosed guns are often found on surface warships as secondary or defensive armament (such as the US Navy's [[5"/25 caliber gun|5-inch (127 mm)/25 caliber]] gun which was removed from battleships to mount on submarines), the term "deck gun" normally refers only to such weapons when mounted on submarines.

==History ==
===World War I===
The deck gun was introduced in all submarine forces prior to [[World War I]].{{citation needed|date=January 2022}}  However, it came to the fore in the German navy, and proved its worth when [[U-boat]]s needed to conserve [[torpedo]]es or attack enemy vessels straggling behind a [[convoy]]. Submarine captains often considered the deck gun as their main weapon, using much more expensive but not always accurate torpedoes only when necessary or advisable (as a deck gun necessarily revealed a submarine's position, whereas a torpedo could be used either under water or effectively at night).  In addition, submarines carried many more gun rounds than torpedoes - ten or fewer during World War I, fired in spreads of multiple warheads to increase the likelihood of a successful hit.

An example of this approach was [[Lothar von Arnauld de la Perière]], who used a deck gun or a dynamiting team on 171 of his 194 sinkings.{{Citation needed|date=August 2011}}

The Royal Navy tried an innovative approach in World War I with its three [[British M-class submarine|M-class submarine]]s, which mounted a single [[Armstrong Whitworth 12 inch /40 naval gun|12 inch (305 mm)/40 caliber naval gun]] intended to be fired while the submarine was at [[periscope depth]] with the muzzle of the gun above water, principally in a [[shore bombardment]] role. This design was found unworkable in trials because the submarine was required to surface to reload the gun, and problems arose when variable amounts of water entered the barrel prior to firing.

===World War II===
The French submarine {{ship|French submarine|Surcouf||2}} was [[Ceremonial ship launching|launched]] in 1929 with two [[203mm/50 Modèle 1924 gun|203&nbsp;mm/50 Modèle 1924 gun]]s in a [[Gun turret|turret]] forward of the [[conning tower]].<ref>{{cite book | last=le Masson | first=Henri | title=The French Navy | publisher=Doubleday and Company | series=Navies of the Second World War | volume=1 | date=1969 | location=Garden City, New York | page=157}}</ref> These were the second largest guns carried by any submarine after the British {{HMS|M1|1917|6}} during the [[Second World War]].<ref name="Campbell">{{cite book | title=Naval Weapons of World War Two |last=Campbell |first=John |publisher=Naval Institute Press |year=1985 |isbn=0-87021-459-4 |page=290}}</ref> The [[London Naval Treaty]] of 1930 restricted submarine guns to a maximum of 155&nbsp;mm (6.1 inches).

In the early part of [[World War II]], German submarine commanders favored the deck gun for similar reasons as their World War I counterparts; the limited number of torpedoes that could be carried, the unreliability of torpedoes, and because their boats could only travel submerged at slow speed for short distances.<ref>{{cite magazine |url=https://nationalinterest.org/blog/buzz/how-nazi-submarine-somehow-sneaked-royal-navy-base-and-sunk-battleship-53312?page=0%2C1 |title=How a Nazi Submarine Somehow Sneaked into a Royal Navy Base and Sunk a Battleship |date=19 April 2019 |magazine=[[The National Interest]] |access-date=19 April 2019}}</ref> The deck gun became less effective as convoys became larger and better equipped, and merchant ships were armed. Surfacing also became dangerous in the vicinity of a convoy because of improvements in radar and direction finding. (See [[Defensively equipped merchant ship]]s (DEMS) and [[United States Navy Armed Guard]]). German U-boat deck guns were eventually removed on the order of the supreme commander of the [[U-boat Arm]] ([[BdU]]) during World War II, and those deck guns that remained were no longer manned. For a few months in 1943, some U-boats operating in the [[Bay of Biscay]] were equipped with [[Type VII submarine#U-flak .22Flak Traps.22|enhanced anti-aircraft guns]] (at the trade-off of reduced torpedo loadouts), being known as "U-Flak" boats to be deployed as service escorts for regular U-boats. After the [[Royal Air Force]] modified their anti-submarine tactics which made it too dangerous for a submarine to stay on the surface to fight, the U-Flaks were converted back to standard U-boat armament configuration.

Japanese [[submarine cruiser]]s used [[14 cm/40 11th Year Type naval gun]]s to shell [[Bombardment of Ellwood|California]], [[Estevan Point#Estevan Point lighthouse attack|British Columbia]] and [[Bombardment of Fort Stevens|Oregon]] during World War II.<ref>{{cite book |last=Webber |first=Bert |title=Retaliation: Japanese Attacks and Allied Countermeasures on the Pacific Coast in World War II |year=1975 |publisher=Oregon State University Press |isbn=978-0-87071-076-6 |pages=14–16 & 40–62}}</ref>

Two notable deck guns from German U-boats used in [[World War II]] were the [[8.8 cm SK C/35 naval gun|{{convert|8.8|cm|in|abbr=on}} SK C/35]] (not to be confused with [[8.8 cm Flak 18/36/37/41|8.8 cm Flak]]<ref>{{cite web |url=http://uboat.net/technical/guns.htm |website=uboat.net |title=The Deck guns}}</ref>) and the [[10.5 cm SK C/32 naval gun|{{convert|10.5|cm|in|abbr=on}} SK C/32]]. The 88&nbsp;mm had ammunition that weighed about {{convert|30|lb|kg|abbr=on}} and was of the projectile and cartridge type. It had the same controls on both sides of the gun so that the two crewmen that were in charge of firing it could control the gun from either side. The 105&nbsp;mm evolved from the 88&nbsp;mm in the sense that it was more accurate and had more power due to the {{convert|51|lb|kg|abbr=on}} ammunition it fired.

In the [[US Navy]], deck guns were used through the end of World War II, with a few still equipped in the early 1950s.{{sfnp|Friedman|1994|page=43}} Many targets in the [[Pacific War]] were [[sampan]]s or other small vessels that were not worth a torpedo. The unreliability of the [[Mark 14 torpedo]] through mid-1943 also promoted the use of the deck gun. Most US submarines started the war with a single [[3"/50 caliber gun|3-inch (76 mm)/50 caliber]] deck gun, adopted in the 1930s to discourage commanders from engaging heavily armed escorts. However, the aging [[United States S-class submarine|S-boats]] were equipped with a [[4"/50 caliber gun|4-inch (102 mm)/50 caliber]] gun, which was often used to re-equip 3-inch-gunned submarines as the S-boats were transferred to training duties beginning in mid-1942. By 1944 most front-line submarines had been refitted with a [[5"/25 caliber gun|5-inch (127 mm)/25 caliber]] gun, and some were equipped with two 5-inch guns.{{sfnp|Friedman|1995|pp=214-219}} The [[cruiser submarine]]s {{USS|Argonaut|SM-1|6}}, {{USS|Narwhal|SS-167|2}} and {{USS|Nautilus|SS-168|2}} were each fitted with two [[6"/53 caliber gun]]s Mark 18 (152&nbsp;mm) as built in the 1920s, the largest deck gun to be fitted on any United States submarine.<ref>{{cite book| title=Naval Weapons of World War Two |last=Campbell |first=John |publisher=Naval Institute Press |year=1985 |isbn=0-87021-459-4 |page=132}}</ref>

In the [[Royal Navy]], the {{sclass|Amphion|submarine|1}} {{HMS|Andrew|P423|6}} was the last British submarine to be fitted with a deck gun (a [[QF 4 inch naval gun Mk XXIII|QF 4 inch Mk XXIII]]). HMS ''Andrew'' was [[Ship commissioning#Ship decommissioning|decommissioned]] in 1974<ref>{{cite book |last=Akermann |first=Paul |title=Encyclopedia of British Submarines 1901-1955 |url=https://books.google.com/books?id=boO7WGL21EQC&q=Amphion+class+submarine+deck+gun&pg=PA427 |date=November 2002 |publisher=Periscope Publishing Ltd. |isbn=978-1-904381-05-1 |pages=426–427}}</ref> and the deck gun is now in the [[Royal Navy Submarine Museum]].

The last submarines in service in any navy to mount a deck gun were two of the four {{sclass|Abtao|submarine|1}}s of the [[Peruvian Navy]] in 1999.{{sfnp|Miller|2002|pp=312–313}}

==See also==
*[[Naval artillery]]
*[[List of naval guns]]

==References==
{{Reflist}}

===Bibliography===
* {{cite book |last=Friedman |first=Norman |author-link=Norman Friedman |title=U.S. Submarines Since 1945: An Illustrated Design History |publisher=[[United States Naval Institute]] |location=[[Annapolis, Maryland]] |year=1994 |isbn=1-55750-260-9 }}
* {{cite book |last=Friedman |first=Norman |title=U.S. Submarines Through 1945: An Illustrated Design History |publisher=United States Naval Institute |year=1995 |location=Annapolis, Maryland |isbn=1-55750-263-3 }}
*{{cite book |last=Miller |first=David |title=The Illustrated Directory of Submarines of the World |year=2002 
 |publisher=MBI Publishing Company |location=St. Paul, Minnesota |isbn=0-7603-1345-8 }}
* {{cite web |url=http://www.uboataces.com/weapon-deck-gun.shtml |title=Weapons: Deck Guns |website=U-boat Aces}}
* {{cite web |url=http://www.uboataces.com/tactics-deckgun.shtml |title=Tactics: U-Boat Deck Gun Attacks |website=U-boat Aces}}

==External links==
* {{cite book |url=https://play.google.com/store/books/details/Michael_Sturma_Surface_and_Destroy?id=Gqmwpe9QFjMC |first=Michael |last=Sturma |title=Surface and Destroy — The Submarine Gun War in the Pacific |date=2 March 2011 |publisher=University Press of Kentucky |isbn=978-0-81312-996-9}}
* {{cite web |url=http://www.fleetsubmarine.com/5_25_gun.html |title=5"/25-Caliber Submarine Deck Gun |website=Fleet Submarine |url-status=dead |archive-url=https://web.archive.org/web/20101122110329/http://www.fleetsubmarine.com/5_25_gun.html |archive-date=22 November 2010}}
* {{cite web |url=http://www.navweaps.com/Weapons/WNUS_5-25_mk10.htm |title=5"/25 (12.7 cm) Marks 10, 11, 13 and 17 |website=NavWeaps.com}}
*{{cite AV media |date=February 1917 |title=Der Magische Gürtel |trans-title=The Enchanted Circle |medium=16mm film |language=de |url=http://www.iwm.org.uk/collections/item/object/1060008290 |location=Germany |publisher=Bild- und Film Amt (BUFA) |via=[[Imperial War Museums]]}} (World War I film of a U-boat patrol by [[Lothar von Arnauld de la Perière]], the highest scoring submarine ace of all time, in ''[[SM U-35 (Germany)|U-35]]''. The film depicts the finishing off of ships whose crews have been allowed to abandon them, in accordance with rules that Germany followed early in the war. The dynamiting team, deck gun, and one torpedo attack are shown. In six parts, silent with German caption slides and English subtitles.)
*{{cite AV media |date=8 July 1945 |title=USS Cod fires machine guns, deck gun, and torpedoes, to scuttle Dutch submarine, ''O-19'', after rescuing her crew in World War II |medium=16mm film |url=http://www.criticalpast.com/video/65675076088_USS-Cod_50-caliber-machine-gun_gun-crew-firing_navigator-with-sextant |publisher=U.S. Navy |via=Criticalpast.com}}

[[Category:Naval artillery]]