Editing Naval mine (section)

== History ==
=== Early use ===
[[File:Chinese Naval Mine.JPG|thumb|upright|A 14th-century illustration of a naval mine and page description from the ''[[Huolongjing]]'']]

Naval mines were first invented by Chinese innovators of [[History of China|Imperial China]] and were described in thorough detail by the early [[Ming dynasty]] artillery officer [[Jiao Yu]], in his 14th-century military treatise known as the ''[[Huolongjing]]''.<ref name="needham volume 5 part 7 203 205">Needham, Volume 5, Part 7, 203–205.</ref> [[History of Science and Technology in China|Chinese records]] tell of naval explosives in the 16th century, used to fight against Japanese pirates (''[[wokou]]''). This kind of naval mine was loaded in a wooden box, sealed with [[putty]]. General [[Qi Jiguang]] made several timed, drifting explosives, to harass Japanese pirate ships.<ref>{{cite book |title=Origins of Chinese science and technology |page=18 |author=Asiapac Editorial |url=https://books.google.com/books?id=C12zMvE1Y_0C&pg=PA18 |publisher=Asiapac Books |year=2007 |edition=3 |isbn=978-981-229-376-3 }}{{Dead link|date=September 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''[[Tiangong Kaiwu]]'' (''The Exploitation of the Works of Nature'') treatise, written by [[Song Yingxing]] in 1637, describes naval mines with a ripcord pulled by hidden ambushers located on the nearby shore who rotated a steel wheel flint mechanism to produce sparks and ignite the fuze of the naval mine.<ref name = "needham volume 5 part 7 205"/> Although this is the rotating steel wheel's first use in naval mines, [[Jiao Yu]] described their use for [[land mine]]s in the 14th century.<ref name="needham volume 5 part 7 199">Needham, Volume 5, Part 7, 199.</ref>

The first plan for a sea mine in the West was by Ralph Rabbards, who presented his design to Queen [[Elizabeth I of England]] in 1574.<ref name="needham volume 5 part 7 205">Needham, Volume 5, Part 7, 205.</ref> The Dutch inventor [[Cornelius Drebbel]] was employed in the Office of Ordnance by [[King Charles I of England]] to make weapons, including the failed "floating petard".<ref>{{cite web | url = https://www.bbc.co.uk/history/historic_figures/drebbel_cornelis.shtml | title = Historic Figures: Cornelius Drebbel (1572–1633) | work = BBC History | access-date = 2007-03-05 | archive-date = 27 December 2019 | archive-url = https://web.archive.org/web/20191227012831/http://www.bbc.co.uk/history/historic_figures/drebbel_cornelis.shtml | url-status = live }}</ref> Weapons of this type were apparently tried by the English at the [[Siege of La Rochelle]] in 1627.<ref>{{cite book | title = Discoveries and inventions of the 19th century | author=Robert Routledge | isbn= 1-85170-267-9 | publisher = Bracken Books | year = 1989 |page = 161}}</ref>

[[File:Bushnell mines.jpg|thumb|left|upright|[[David Bushnell (inventor)|David Bushnell’s]] mines destroying a British ship in 1777]]
American [[David Bushnell (inventor)|David Bushnell]] developed the first American naval mine, for use against the British in the [[American War of Independence]].<ref>{{cite book|url=https://books.google.com/books?id=fAfP2w6SgK8C&pg=PA12|page=12|title=Oceanography and Mine Warfare|author=National Research Council (U.S.). Ocean Studies Board, National Research Council (U.S.). Commission on Geosciences, Environment, and Resources|publisher=National Academies Press|year=2000|isbn=0-309-06798-7|access-date=2011-12-31}}</ref> It was a watertight keg filled with [[gunpowder]] that was floated toward the enemy, detonated by a sparking mechanism if it struck a ship. It was used on the [[Delaware River]] as a drift mine, destroying a small boat near its intended target, a British warship.<ref>Gilbert, Jason A., L/Cdr, USN. "Combined Mine Countermeasures Force", Naval War College paper (Newport, RI, 2001), p. 2.</ref>

=== The 19th century ===
[[File:Waud - infernal machines.jpg|thumb|upright|Infernal machines in the [[Potomac River]] in 1861 during the [[American Civil War]], sketch by [[Alfred Waud]]]]

The 1804 [[Raid on Boulogne]] made extensive use of explosive devices designed by inventor [[Robert Fulton]]. The 'torpedo-catamaran' was a coffer-like device balanced on two wooden floats and steered by a man with a paddle. Weighted with lead so as to ride low in the water, the operator was further disguised by wearing dark clothes and a black cap.<ref name="Philip161">{{cite book |last=Philip |title=Robert Fulton |page=161}}</ref> His task was to approach the French ship, hook the torpedo to the anchor cable and, having activated the device by removing a pin, remove the paddles and escape before the torpedo detonated.<ref name="Best80">{{cite book |last=Best |title=Trafalgar |page=80}}</ref> Also to be deployed were large numbers of casks filled with gunpowder, ballast and combustible balls. They would float in on the tide and on washing up against an enemy's hull, explode.<ref name="Best80"/> Also included in the force were several [[Fire ship|fireships]], carrying 40 barrels of gunpowder and rigged to explode by a clockwork mechanism.<ref name="Best80"/>

In 1812, Russian engineer [[Pavel Shilling]] exploded an underwater mine using an [[electrical circuit]]. In 1842 [[Samuel Colt]] used an electric detonator to destroy a moving vessel to demonstrate an underwater mine of his own design to the [[United States Navy]] and President [[John Tyler]]. However, opposition from former president [[John Quincy Adams]], scuttled the project as "not fair and honest warfare".<ref>Schiffer, Michael B. (2008). ''Power struggles: scientific authority and the creation of practical electricity before Edison.'' Cambridge, Massachusetts: MIT Press. {{ISBN|978-0-262-19582-9}}.</ref> In 1854, during the unsuccessful attempt of the Anglo-French (101 warships) fleet to seize the [[Kronshtadt|Kronstadt]] fortress, British steamships {{HMS|Merlin|1838|6}} (9 June 1855, the first successful mining in Western history), {{HMS|Vulture|1843|6}} and HMS ''Firefly'' suffered damage due to the underwater explosions of Russian naval mines. Russian naval specialists set more than 1,500 naval mines, or ''infernal machines'', designed by [[Moritz von Jacobi]] and by [[Immanuel Nobel]],<ref>{{cite book |last1=Youngblood |first1=Norman |title=The Development of Mine Warfare: A Most Murderous and Barbarous Conduct |url=https://books.google.com/books?id=WToYXxVaKKgC |series=Praeger Security International; War, technology, and history |issn=1556-4924 |publisher=Greenwood Publishing Group |date=2006 |page=29 |isbn=9780275984199 |access-date=31 January 2016 |quote=The Crimean War (1854–1856) was the first war to see the successful use of land and sea mines, both of which were the work of Immanuel Nobel.}}</ref> in the [[Gulf of Finland]] during the [[Crimean War]] of 1853–1856. The mining of ''Vulcan'' led to the world's first [[minesweeping]] operation.<ref>{{cite book |last1=Nicholson |first1=Arthur |title=Very Special Ships: Abdiel Class Fast Minelayers of World War Two |url=http://navalinstitute.com.au/very-special-ships-abdiel-class-fast-minelayers-of-wwii-2/ |publisher=Seaforth Publishing |date=2015 |page=11 |isbn=9781848322356 |access-date=31 January 2016 |quote=While nosing about the defences off Kronstadt on 9 June 1855, the British paddle steamer ''Merlin'' struck first one and then another mine, giving her the dubious distinction of being the first warship damaged by enemy mines. HMS ''Firefly'' came to her assistance after the first explosion, only to strike a mine herself. [...] When HMS ''Vulcan'' struck a mine on 20 June, the Royal Navy had had enough, and the next day began carrying out the first minesweeping operation in history, recovering thirty-three 'infernal machines,' the standard British term of the day for sea mines.}}</ref><ref>{{cite book |last1=Lambert |first1=Andrew D. |author-link1=Andrew Lambert |year=1990 |title=The Crimean War: British Grand Strategy Against Russia, 1853–56 |url=https://books.google.com/books?id=GCVyIZEdc6kC |publisher=Ashgate Publishing, Ltd. |publication-date=2011 |pages=288–289 |isbn=9781409410119 |access-date=31 January 2016 |quote=On 9 June ''Merlin'', ''Dragon'', ''Firefly'' and ''D'Assas'' took Penaud and several British captains to examine Cronstadt. While still 2 miles out the two surveying ships were struck by 'infernals'. [...] The fleet left [[Seskar]] on the 20th. ''Vulture'', almost the last to arrive, was struck by an infernal. The following day the boats fished up several of the primitive mines, and both Dundas and Seymour inspected them aboard their flagships.}}</ref> During the next 72 hours, 33 mines were swept.<ref>Brown. D.K., Before the Ironclad, London (1990), pp. 152–154</ref>

The [[Jacobi mine]] was designed by German-born, Russian engineer Jacobi, in 1853. The mine was tied to the sea bottom by an anchor. A cable connected it to a [[galvanic cell]] which powered it from the shore, the power of its explosive charge was equal to {{cvt|14|kg}} of [[black powder]]. In the summer of 1853, the production of the mine was approved by the Committee for Mines of the [[Ministry of War of the Russian Empire]]. In 1854, 60 Jacobi mines were laid in the vicinity of the Forts Pavel and [[Fort Alexander (Saint Petersburg)|Alexander]] ([[Kronstadt]]), to deter the [[Baltic Fleet (United Kingdom)|British Baltic Fleet]] from attacking them. It gradually phased out its direct competitor the Nobel mine on the insistence of Admiral [[Fyodor Litke]]. The Nobel mines were bought from Swedish industrialist [[Immanuel Nobel]] who had entered into [[collusion]] with the Russian head of navy [[Alexander Sergeyevich Menshikov]]. Despite their high cost (100 [[Russian ruble]]s) the Nobel mines proved to be faulty, exploding while being laid, failing to explode or detaching from their wires, and drifting uncontrollably, at least 70 of them were subsequently disarmed by the British. In 1855, 301 more Jacobi mines were laid around Krostadt and [[Lisy Nos]]. British ships did not dare to approach them.{{sfn|Tarle|1944|pp=44–45}}

In the 19th century, mines were called [[torpedo]]es, a name probably conferred by [[Robert Fulton]] after the [[torpedo fish]], which gives powerful [[electric shock]]s. A [[spar torpedo]] was a mine attached to a long pole and detonated when the ship carrying it rammed another one and withdrew a safe distance. The submarine {{ship||H. L. Hunley|submarine|2}} used one to sink {{USS|Housatonic|1861|6}} on 17 February 1864. A Harvey torpedo was a type of floating mine towed alongside a ship and was briefly in service in the [[Royal Navy]] in the 1870s. Other "torpedoes" were attached to ships or propelled themselves. One such weapon called the [[Whitehead torpedo]] after its inventor, caused the word "torpedo" to apply to self-propelled underwater missiles as well as to static devices. These mobile devices were also known as "fish torpedoes".

The [[American Civil War]] of 1861–1865 also saw the successful use of mines. The first ship sunk by a mine, {{USS|Cairo}}, foundered in 1862 in the [[Yazoo River]]. [[Rear Admiral]] [[David Farragut]]'s famous command during the [[Battle of Mobile Bay]] in 1864, "[[Damn the torpedoes, full speed ahead!]]"{{refn|Farragut's actual wording has been recorded as, "Damn the torpedoes. Four bells, Captain Drayton, go ahead. Jouett, full speed."|group="note"}} refers to a minefield laid at [[Mobile, Alabama|Mobile]], Alabama.

After 1865 the United States adopted the mine as its primary weapon for [[Seacoast defense in the United States|coastal defense]]. In the decade following 1868, Major [[Henry Larcom Abbot]] carried out a lengthy set of experiments to design and test moored mines that could be exploded on contact or be detonated at will as enemy shipping passed near them. This initial development of mines in the United States took place under the purview of the [[United States Army Corps of Engineers|U.S. Army Corps of Engineers]], which trained officers and men in their use at the [[U.S. Army Engineer School|Engineer School of Application]] at Willets Point, New York (later named [[Fort Totten (Queens)|Fort Totten]]). In 1901 underwater minefields became the responsibility of the US Army's Artillery Corps, and in 1907 this was a founding responsibility of the [[United States Army Coast Artillery Corps]].<ref>{{cite web|url=http://cdsg.org/coast-artillery-submarine-mine-defenses/|title=Coast Artillery: Submarine Mine Defenses|date=25 May 2016|access-date=11 September 2017|archive-date=11 September 2017|archive-url=https://web.archive.org/web/20170911161715/http://cdsg.org/coast-artillery-submarine-mine-defenses/|url-status=live}}</ref>

The [[Imperial Russian Navy]], a pioneer in mine warfare, successfully deployed mines against the [[Ottoman Navy]] during both the Crimean War and the [[Russo-Turkish War (1877-1878)]].<ref name= Kowner>{{cite book |last=Kowner |first=Rotem |author-link=Rotem Kowner |year=2006 |title=Historical Dictionary of the Russo-Japanese War |publisher=The Scarecrow Press |page=238 |isbn=0-8108-4927-5}}</ref>

During the [[War of the Pacific]] (1879-1883), the [[Peruvian Navy]], at a time when the Chilean squadron was blockading the Peruvian ports, formed a brigade of torpedo boats under the command of the frigate captain Leopoldo Sánchez Calderón and the Peruvian engineer [[:es: Manuel Cuadros|Manuel Cuadros]], who perfected the naval torpedo or mine system to be electrically activated when the cargo weight was lifted. This is how, on 3 July 1880, in front of the port of [[Callao]], the gunned transport ''[[:es: Vapor Loa|Loa]]'' flies when capturing a sloop mined by the Peruvians. A similar fate occurred with the gunboat schooner ''[[:es: Goleta Covadonga|Covadonga]]'' in front of the port of [[Chancay]], on 13 September 1880, which having captured and checked a beautiful boat, it exploded when hoisting it on its side.<ref>{{cite web|url=https://www.usmcu.edu/Outreach/Marine-Corps-University-Press/MCU-Journal/JAMS-vol-13-no-2/The-Port-Hopping-War/|title=The Port-Hopping War|access-date=15 October 2022|archive-date=15 October 2022|archive-url=https://web.archive.org/web/20221015000323/https://www.usmcu.edu/Outreach/Marine-Corps-University-Press/MCU-Journal/JAMS-vol-13-no-2/The-Port-Hopping-War/|url-status=live}}</ref>

During the [[Battle of Tamsui]] (1884), in the [[Keelung Campaign]] of the [[Sino-French War]], Chinese forces in Taiwan under [[Liu Mingchuan]] took measures to reinforce [[Tamsui]] against the French; they planted nine torpedo mines in the river and blocked the entrance.<ref>{{cite book |title=Maritime Taiwan: Historical Encounters with the East and the West |last=Tsai |first=Shih-shan Henry |edition=illustrated |year=2009 |publisher=M.E. Sharpe |url=https://books.google.com/books?id=hlnKRaZ0f4QC&q=taiwan+matchlocks+stones&pg=PA97 |archive-url=https://books.google.com/books?id=abMMAQAAMAAJ&q=taiwan+matchlocks+stones&dq=taiwan+matchlocks+stones&hl=en&sa=X&ei=ZHBJVMP8HKz-sATi64HADQ&ved=0CE0Q6AEwBw |archive-date=13 July 2010 |page=97 |isbn=978-0765623287 |access-date=24 April 2014}}</ref>

=== Early 20th century ===
During the [[Boxer Rebellion]], Imperial Chinese forces deployed a command-detonated<!--described as "electric", this makes sense--> mine field at the mouth of the [[Hai River]] before the [[Battle of Dagu Forts (1900)|Dagu forts]], to prevent the western [[Eight-Nation Alliance|Allied forces]] from sending ships to attack.<ref>{{cite book |last=MacCloskey |first=Monro |url=https://books.google.com/books?id=UHbxAAAAMAAJ&q=electric+mines |title=Reilly's Battery: a story of the Boxer Rebellion |year=1969 |publisher=R. Rosen Press |page=95 |isbn=9780823901456 |access-date=19 February 2011}}(Original from the University of Wisconsin – Madison)</ref><ref>{{cite book |last1=Slocum |first1=Stephan L'H. |last2=Reichmann |first2=Carl |last3=Chaffee |first3=Adna Romanza |url=https://archive.org/details/reportsonmilita02divigoog |quote=15 June, it was learned that the mouth of the river was protected by electric mines, that the forts at Taku were. |title=Reports on military operations in South Africa and China |year=1901 |publisher=[[United States Government Printing Office|GPO]] |location=Adjutant-General's Office, Military Information Division, Washington, D.C., United States |page=[https://archive.org/details/reportsonmilita02divigoog/page/n584 533] |access-date=19 February 2011}}(Issue 143 of Document (United States. War Dept.))(Original from the New York Public Library)</ref>

The next major use of mines was during the [[Russo-Japanese War]] of 1904–1905. Two mines blew up when the {{ship|Russian battleship|Petropavlovsk|1894|2}} struck them near [[Port Arthur naval base|Port Arthur]], sending the holed vessel to the bottom and killing the fleet commander, Admiral [[Stepan Makarov]], and most of his crew in the process. The toll inflicted by mines was not confined to the Russians, however. The [[Imperial Japanese Navy|Japanese Navy]] lost two battleships, four cruisers, two destroyers and a torpedo-boat to offensively laid mines during the war. Most famously, on 15 May 1904, the Russian [[minelayer]] [[Amur-class minelayer (1898)|''Amur'']] planted a 50-mine minefield off [[Lüshunkou District|Port Arthur]] and succeeded in sinking the Japanese battleships {{ship|Japanese battleship|Hatsuse||2}} and {{ship|Japanese battleship|Yashima||2}}.

Following the end of the Russo-Japanese War, several nations attempted to have mines banned as weapons of war at the [[Hague Peace Conference (1907)]].<ref name= Kowner/>

Many early mines were fragile and dangerous to handle, as they contained glass containers filled with [[nitroglycerin]] or mechanical devices that activated a blast upon tipping. Several mine-laying ships were destroyed when their cargo exploded.<ref>{{cite web |url=http://www.worldwideinvention.com/articles/details/312/naval-mine-contained-explosive-device-placed-in-water-to-destroy-ships-or-submarines.html |title=Naval mine - contained explosive device placed in water to destroy ships or submarines |date=Nov 24, 2009 |website=World Wide Inventions |access-date=2012-08-12 |url-status=dead |archive-url=https://web.archive.org/web/20131103144718/http://www.worldwideinvention.com/articles/details/312/Naval-mine-contained-explosive-device-placed-in-water-to-destroy-ships-or-submarines.html |archive-date=2013-11-03 }}</ref>

Beginning around the start of the 20th century, submarine mines played a major role in the defense of U.S. harbours against enemy attacks as part of the [[Board of Fortifications|Endicott and Taft Programs]]. The mines employed were controlled mines, anchored to the bottoms of the harbours, and detonated under control from large mine [[casemate]]s onshore.

[[File:Women testing a mine with air presssure (15146368860).jpg|thumb|British war workers using air pressure to test naval mines during World War&nbsp;I]]
During [[World War I]], mines were used extensively to defend coasts, coastal shipping, ports and naval bases around the globe. The Germans laid mines in shipping lanes to sink merchant and naval vessels serving Britain. The Allies targeted the German U-boats in the Strait of Dover and the Hebrides. In an attempt to seal up the northern exits of the North Sea, the Allies developed the [[North Sea Mine Barrage]]. During a period of five months from June 1918, almost 70,000 mines were laid spanning the North Sea's northern exits. The total number of mines laid in the North Sea, the British East Coast, Straits of Dover, and Heligoland Bight is estimated at 190,000 and the total number during the whole of WWI was 235,000 sea mines.<ref>{{cite web|url=http://www.seaclimate.com/5/pdf/5_14.pdf|title=Climate Change & Naval War—A Scientific Assessment 2005—Trafford on demand publishing, Canada/UK|url-status=dead|archive-url=https://web.archive.org/web/20080908115540/https://www.seaclimate.com/5/pdf/5_14.pdf|archive-date=2008-09-08|access-date=10 October 2009}}</ref> Clearing the barrage after the war took 82 ships and five months, working around the clock.<ref>Gilbert, p. 4.</ref> It was also during World War I, that the British [[hospital ship]], {{HMHS|Britannic}}, became the largest vessel ever sunk by a naval mine{{citation needed|date=January 2022}}. The ''Britannic'' was [[Olympic-class ocean liner|the sister ship]] of the [[Titanic|RMS ''Titanic'']], and the {{RMS|Olympic}}.<ref>{{cite web |url=http://www.markchirnside.co.uk/MARK_CHIRNSIDE_INTERVIEW_JANUARY_2005.htm |title=Mark Chirnside's Reception Room: Olympic, Titanic & Britannic: Olympic Interview, January 2005 |publisher=Markchirnside.co.uk |access-date=16 January 2022 |archive-date=29 January 2021 |archive-url=https://web.archive.org/web/20210129150626/http://www.markchirnside.co.uk/MARK_CHIRNSIDE_INTERVIEW_JANUARY_2005.htm |url-status=live }}{{Self-published source|date=January 2022}}</ref>

=== World War II ===
[[File:Bundesarchiv Bild 101II-MN-1559-33, Auf See, beim Minen legen.jpg|thumb|upright|A contact mine being deployed from the German minelayer {{ship|German minelayer|Hansestadt Danzig||2}}]]
During [[World War II]], the [[U-boat]] fleet, which dominated much of the battle of the Atlantic, was small at the beginning of the war and much of the early action by German forces involved mining [[convoy]] routes and ports around Britain. German submarines also operated in the [[Mediterranean Sea]], in the [[Caribbean Sea]], and along the U.S. coast.

Initially, contact mines (requiring a ship to physically strike a mine to detonate it) were employed, usually tethered at the end of a cable just below the surface of the water. Contact mines usually blew a hole in ships' hulls. By the beginning of World War II, most nations had developed mines that could be dropped from aircraft, some of which floated on the surface, making it possible to lay them in enemy harbours. The use of dredging and nets was effective against this type of mine, but this consumed valuable time and resources and required harbours to be closed.

Later, some ships survived mine blasts, limping into port with buckled plates and broken backs. This appeared to be due to a new type of mine, detecting ships by their proximity to the mine (an influence mine) and detonating at a distance, causing damage with the shock wave of the explosion. Ships that had successfully run the gantlet<!-- properly gantlet, not gauntlet --> of the Atlantic crossing were sometimes destroyed entering freshly cleared British harbours. More shipping was being lost than could be replaced, and [[Winston Churchill|Churchill]] ordered the intact recovery of one of these new mines to be of the highest priority.

[[File:L L sweeping gear.jpg|thumb|The towed, electric cables of ''Double-L'', magnetic–minesweeping gear being deployed behind a Royal Navy minesweeper]]
The British experienced a stroke of luck in November 1939, when a German mine was dropped from an aircraft onto the mudflats off [[Shoeburyness]] during low tide. Additionally, the land belonged to the army and a base with men and workshops was at hand. Experts were dispatched from {{HMS|Vernon}} to investigate the mine. The Royal Navy knew that mines could use magnetic sensors, Britain having developed magnetic mines in World War I, so everyone removed all metal, including their buttons, and made tools of non-magnetic [[brass]].<ref>Campbell, John, "Naval Weapons of World War Two" (London: Conway Maritime Press, 1985)</ref> They disarmed the mine and rushed it to the labs at HMS Vernon, where scientists discovered that the mine had a magnetic arming mechanism. A large ferrous object passing through the Earth's [[magnetic field]] will concentrate the field through it, due to its magnetic permeability; the mine's detector was designed to trigger as a ship passed over when the Earth's magnetic field was concentrated in the ship and away from the mine. The mine detected this loss of the magnetic field which caused it to detonate. The mechanism had an adjustable sensitivity, calibrated in [[Gauss (unit)|milligauss]].

[[File:Dwi wellington front.jpg|thumb|A [[Vickers Wellington]] fitted with a ''DWI'', magnetic mine exploder, [[Ismailia]], Egypt]]
From this data, known methods were used to clear these mines. Early methods included the use of large electromagnets dragged behind ships or below low-flying aircraft (a number of older bombers like the [[Vickers Wellington]] were used for this). Both of these methods had the disadvantage of "sweeping" only a small strip. A better solution was found in the "Double-L Sweep"<ref>{{cite web|url=http://www.goodeveca.net/CFGoodeve/cfg_bio.html#sweep|title=The Double-L Sweep – Biography of Sir Charles Goodeve|access-date=9 July 2008|archive-date=18 October 2008|archive-url=https://web.archive.org/web/20081018181128/http://www.goodeveca.net/CFGoodeve/cfg_bio.html#sweep|url-status=live}}</ref> using electrical cables dragged behind ships that passed large pulses of current through the seawater. This created a large magnetic field and swept the entire area between the two ships. The older methods continued to be used in smaller areas. The [[Suez Canal]] continued to be swept by aircraft, for instance.

While these methods were useful for clearing mines from local ports, they were of little or no use for enemy-controlled areas. These were typically visited by warships, and the majority of the fleet then underwent a massive [[Degaussing#Ships.27 hulls|degaussing]] process, where their hulls had a slight "south" bias induced into them which offset the concentration-effect almost to zero.

Initially, major warships and large troopships had a copper ''degaussing coil'' fitted around the perimeter of the hull, energized by the ship's electrical system whenever in suspected magnetic-mined waters. Some of the first to be so fitted were the [[aircraft carrier|carrier]] {{HMS|Ark Royal|91|6}} and the liners {{RMS|Queen Mary}} and {{RMS|Queen Elizabeth}}. It was a photo of one of these liners in New York harbour, showing the degaussing coil, which revealed to German Naval Intelligence the fact that the British were using degaussing methods to combat their magnetic mines.<ref>Piekalkiewicz, Janusz, "Sea War: 1939–1945" (Poole, UK: Blandford Press, 1987)</ref> This was felt to be impractical for smaller warships and merchant vessels, mainly because the ships lacked the generating capacity to energise such a coil. It was found that "wiping" a current-carrying cable up and down a ship's hull<ref>{{cite web|url=http://www.goodeveca.net/CFGoodeve/cfg_bio.html#wipe|title=Wiping – Biography of Sir Charles Goodeve|access-date=10 July 2008|archive-date=18 October 2008|archive-url=https://web.archive.org/web/20081018181128/http://www.goodeveca.net/CFGoodeve/cfg_bio.html#wipe|url-status=live}}</ref> temporarily canceled the ships' magnetic signature sufficiently to nullify the threat. This started in late 1939, and by 1940 merchant vessels and the smaller British warships were largely immune for a few months at a time until they once again built up a field.

The cruiser {{HMS|Belfast}} is just one example of a ship that was struck by a magnetic mine during this time. On 21 November 1939, a mine broke her keel, which damaged her engine and boiler rooms, as well as injuring 46 men, one later died from his injuries.  She was towed to [[Rosyth Dockyard|Rosyth]] for repairs.  Incidents like this resulted in many of the boats that sailed to [[Dunkirk evacuation|Dunkirk]] being degaussed in a marathon four-day effort by degaussing stations.{{sfn |Wingate|2004|pp=34–35}}

[[File:Laying mines aboard Finnish minelayer Ruotsinsalmi May 1942 (SA-kuva 88630).jpg|thumb|The Finnish minelayer ''[[Finnish minelayer Ruotsinsalmi|Ruotsinsalmi]]'' lays naval mines in the [[Gulf of Finland]] during the [[Continuation War]]]]
The Allies and Germany deployed acoustic mines in World War II, against which even wooden-[[hull (watercraft)|hull]]ed ships (in particular [[Minesweeper (ship)|minesweeper]]s) remained vulnerable.<ref name="Parillo, p.200">Parillo, p. 200.{{Incomplete short citation|date=May 2020}}</ref> Japan developed sonic generators to sweep these; the gear was not ready by war's end.<ref name="Parillo, p.200"/> The primary method Japan used was small air-delivered bombs. This was profligate and ineffectual; used against acoustic mines at [[Penang]], 200 bombs were needed to detonate just 13 mines.<ref name="Parillo, p.200"/>

The Germans developed a pressure-activated mine and planned to deploy it as well, but they saved it for later use when it became clear the British had defeated the magnetic system. The U.S. also deployed these, adding "counters" which would allow a variable number of ships to pass unharmed before detonating.<ref name="Parillo, p.200"/> This made them a great deal harder to sweep.<ref name="Parillo, p.200"/>

Mining campaigns could have devastating consequences. The U.S. effort against Japan, for instance, closed major ports, such as [[Hiroshima]], for days,<ref name="Parillo, p.201">Parillo, p. 201.{{Incomplete short citation|date=May 2020}}</ref> and by the end of the Pacific War had cut the amount of freight passing through [[Kobe]]–[[Yokohama]] by 90%.<ref name="Parillo, p.201"/>

When the war ended, more than 25,000 U.S.-laid mines were still in place, and the Navy proved unable to sweep them all, limiting efforts to critical areas.<ref name="Gilbert, p.5">Gilbert, p. 5.</ref> After sweeping for almost a year, in May 1946, the Navy abandoned the effort with 13,000 mines still unswept.<ref name="Gilbert, p.5"/> Over the next thirty years, more than 500 minesweepers (of a variety of types) were damaged or sunk clearing them.<ref name="Gilbert, p.5"/>

The U.S. began adding delay counters to their magnetic mines in June 1945.<ref>Parillo, Mark P. ''Japanese Merchant Marine in World War Two'' (Annapolis, Md. : Naval Institute Press, 1993), p. 200.</ref>

=== Cold War era ===
[[File:Ffg58minedamage2.jpg|thumb|In 1988, an Iranian M-08 mine made a {{convert|25|ft|m|0|adj=on}} hole in the hull of the frigate {{USS|Samuel B. Roberts|FFG-58|6}}, forcing the ship to seek temporary repairs in a [[dry dock]] in [[Dubai|Dubai, UAE]].]]
Since [[World War II]], mines have damaged 14 [[United States Navy]] ships, whereas air and missile attacks have damaged four. During the [[Korean War]], mines laid by North Korean forces caused 70% of the casualties suffered by U.S. naval vessels and caused 4 sinkings.<ref>{{cite web |url=https://www.history.navy.mil/research/library/online-reading-room/title-list-alphabetically/m/mine-warfare.html |title=Mine Warfare |first=Edward J. |last=Marolda |publisher=U.S. Naval History & Heritage Command |date=2003-08-26 |access-date=2011-12-31 |archive-date=1 May 2015 |archive-url=https://web.archive.org/web/20150501125344/http://www.history.navy.mil/research/library/online-reading-room/title-list-alphabetically/m/mine-warfare.html |url-status=live }}</ref>

During the [[Iran–Iraq War]] from 1980 to 1988, the belligerents mined several areas of the [[Persian Gulf]] and nearby waters. On 24 July 1987, the supertanker [[Bridgeton incident|''SS'' Bridgeton was mined]] by Iran near Farsi Island. On 14 April 1988, {{USS|Samuel B. Roberts|FFG-58|6}} struck an Iranian mine in the central [[Persian Gulf]] [[shipping lane]], wounding 10 sailors.

In the summer of 1984, magnetic sea mines damaged at least 19 ships in the [[Red Sea]]. The U.S. concluded [[Libya]] was probably responsible for the minelaying.<ref>{{cite web |last=Smith |first=William E. |url=http://www.time.com/time/magazine/article/0,9171,926817,00.html |archive-url=https://web.archive.org/web/20101029151644/http://www.time.com/time/magazine/article/0,9171,926817,00.html |url-status=dead |archive-date=29 October 2010 |title=Terrorism: Scouring the Red Sea Floor |publisher=[[Time (magazine)|Time]] |date=1984-08-27 |access-date=2013-07-07 }}</ref> In response the U.S., Britain, France, and three other nations<ref name="Gilbert, p.8">Gilbert, p. 8.</ref> launched ''Operation Intense Look'', a minesweeping operation in the Red Sea involving more than 46 ships.<ref>Gilbert, p.v5.</ref>

On the orders of the [[Reagan administration]], the [[CIA]] mined [[Nicaragua]]'s [[Puerto Sandino|Sandino]] port in 1984 in support of the [[Contras]].<ref>{{cite web |url=http://www.ontheissues.org/Celeb/Ronald_Reagan_Foreign_Policy.htm |title=Reagan foreign policy |publisher=Ontheissues.org |access-date=2013-07-07 |archive-date=4 January 2010 |archive-url=https://web.archive.org/web/20100104080331/http://www.ontheissues.org/Celeb/Ronald_Reagan_Foreign_Policy.htm |url-status=live }}</ref> A Soviet tanker was among the ships damaged by these mines.<ref>{{cite web |url=http://homepage.ntlworld.com/jksonc/docs/US-mining-nicaragua-harbors.html |title=U.S. Mining Nicaragua's harbours (February–March 1984) |publisher=Homepage.ntlworld.com |access-date=2013-07-07 |url-status=dead |archive-url=https://web.archive.org/web/20130313101103/https://homepage.ntlworld.com/jksonc/docs/US-mining-nicaragua-harbors.html |archive-date=2013-03-13 }}</ref> In 1986, in the case of ''[[Nicaragua v. United States]]'', the [[International Court of Justice]] ruled that this mining was a violation of international law.

=== Post Cold War ===
During the [[Gulf War]], [[Iraq]]i naval mines severely damaged {{USS|Princeton|CG-59|6}} and {{USS|Tripoli|LPH-10|6}}.<ref>{{cite web |url=http://www.navysite.de/cg/cg59.html |title=USS ''Princeton'' (CG 59) |publisher=Unofficial US Navy Site |first=Thoralf |last=Doehring |access-date=2011-12-31 |archive-date=30 April 2011 |archive-url=https://web.archive.org/web/20110430025644/http://navysite.de/cg/cg59.html |url-status=live }}</ref> When the war concluded, eight countries conducted clearance operations.<ref name="Gilbert, p.8"/>

Houthi forces in the [[Yemeni Civil War (2014–present)|Yemeni Civil War]] have made frequent use of naval mines, laying over 150 in the Red Sea throughout the conflict.<ref>{{Cite web|url=https://www.longwarjournal.org/archives/2020/03/houthis-increase-use-of-suicide-drone-boats-in-recent-weeks.php|title=Houthis increase use of suicide drone boats in recent weeks &#124; FDD's Long War Journal|date=11 March 2020|access-date=12 March 2020|archive-date=24 March 2020|archive-url=https://web.archive.org/web/20200324142002/https://www.longwarjournal.org/archives/2020/03/houthis-increase-use-of-suicide-drone-boats-in-recent-weeks.php|url-status=live}}</ref>

In the first month of the [[2022 Russian invasion of Ukraine]], Ukraine accused Russia of deliberately employing drifting mines in the Black Sea area. Around the same time, Turkish and Romanian military diving teams were involved in defusing operations, when stray mines were spotted near the coasts of these countries. [[London P&I Club]] issued a warning to freight ships in the area, advising them to "maintain lookouts for mines and pay careful attention to local navigation warnings".<ref>{{Cite news |last=Saul |first=Jonathan |date=2022-03-30 |title=Ukraine says Russia planting mines in Black Sea as shipping perils grow |language=en |work=Reuters |url=https://www.reuters.com/world/europe/ukraine-says-russia-planting-mines-black-sea-shipping-perils-grow-2022-03-30/ |access-date=2022-04-08 |archive-date=8 April 2022 |archive-url=https://web.archive.org/web/20220408191718/https://www.reuters.com/world/europe/ukraine-says-russia-planting-mines-black-sea-shipping-perils-grow-2022-03-30/ |url-status=live }}</ref> Ukrainian forces have mined "from the Sea of Azov to the Black Sea which banks the critical city of Odesa."<ref>{{Cite news |date=2022-05-05 |title=Here's what makes sea mines Russia's biggest challenge in Ukraine's Mariupol port |language=en |work=India Today |url=https://www.indiatoday.in/world/story/russia-ukraine-war-mariupol-port-sea-mines-azov-sea-1945555-2022-05-05 |access-date=2022-05-18 |archive-date=18 May 2022 |archive-url=https://web.archive.org/web/20220518061835/https://www.indiatoday.in/world/story/russia-ukraine-war-mariupol-port-sea-mines-azov-sea-1945555-2022-05-05 |url-status=live }}</ref>