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86-679: Operation Starvation was a naval mining operation conducted in World War II by the United States Army Air Forces (USAAF) to disrupt Japanese shipping. The mission was initiated at the insistence of Admiral Chester Nimitz who wanted his naval operations augmented by an extensive mining of Japan conducted by the USAAF. While General Henry H. Arnold felt this was strictly a naval priority, he assigned General Curtis LeMay to carry it out. LeMay assigned one group of about 160 aircraft of

172-449: A clockwork , electronic or chemical delay mechanism), or have some form of arming pin or plug removed. Only when these processes have occurred will the arming process of the series time fuze be complete. Mines often have a parallel time fuze to detonate and destroy the mine after a pre-determined period to minimize casualties after the anticipated duration of hostilities. Detonation of modern naval mines may require simultaneous detection of

258-400: A 4.5 second time fuze, so detonation should occur on impact, but otherwise takes place after 4.5 seconds. Military weapons containing explosives have fuzing systems including a series time fuze to ensure that they do not initiate (explode) prematurely within a danger distance of the munition launch platform. In general, the munition has to travel a certain distance, wait for a period of time (via

344-590: A blast upon tipping. Several mine-laying ships were destroyed when their cargo exploded. 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 Endicott and Taft Programs . The mines employed were controlled mines, anchored to the bottoms of the harbours, and detonated under control from large mine casemates onshore. During World War I , mines were used extensively to defend coasts, coastal shipping, ports and naval bases around

430-462: A certain pre-set distance of the target, or vice versa. Proximity fuzes utilize sensors incorporating one or more combinations of the following: radar , active sonar , passive acoustic, infrared , magnetic , photoelectric , seismic or even television cameras. These may take the form of an anti-handling device designed specifically to kill or severely injure anyone who tampers with the munition in some way e.g. lifting or tilting it. Regardless of

516-430: A fuze arming before it leaves the gun barrel. These safety features may include arming on "setback" or by centrifugal force, and often both operating together. Set-back arming uses the inertia of the accelerating artillery shell to remove a safety feature as the projectile accelerates from rest to its in-flight speed. Rotational arming requires that the artillery shell reach a certain rpm before centrifugal forces cause

602-413: A fuze may be identified by function as the exploder . The relative complexity of even the earliest fuze designs can be seen in cutaway diagrams . A fuze is a device that detonates a munition 's explosive material under specified conditions. In addition, a fuze will have safety and arming mechanisms that protect users from premature or accidental detonation. For example, an artillery fuze's battery

688-401: A harbour by hand. They can be inexpensive: some variants can cost as little as US $ 2,000, though more sophisticated mines can cost millions of dollars, be equipped with several kinds of sensors, and deliver a warhead by rocket or torpedo . Their flexibility and cost-effectiveness make mines attractive to the less powerful belligerent in asymmetric warfare . The cost of producing and laying

774-441: A hole filled with gunpowder leading from the surface to the centre of the projectile. The flame from the burning of the gunpowder propellant ignited this "fuze" on firing, and burned through to the centre during flight, then igniting or exploding whatever the projectile may have been filled with. By the 19th century devices more recognisable as modern artillery "fuzes" were being made of carefully selected wood and trimmed to burn for

860-915: A mine is usually between 0.5% and 10% of the cost of removing it, and it can take up to 200 times as long to clear a minefield as to lay it. Parts of some World War II naval minefields still exist because they are too extensive and expensive to clear. Some 1940s-era mines may remain dangerous for many years. Mines have been employed as offensive or defensive weapons in rivers, lakes, estuaries, seas, and oceans, but they can also be used as tools of psychological warfare . Offensive mines are placed in enemy waters, outside harbours, and across important shipping routes to sink both merchant and military vessels. Defensive minefields safeguard key stretches of coast from enemy ships and submarines, forcing them into more easily defended areas, or keeping them away from sensitive ones. Shipowners are reluctant to send their ships through known minefields. Port authorities may attempt to clear

946-524: A mined area, but those without effective minesweeping equipment may cease using the area. Transit of a mined area will be attempted only when strategic interests outweigh potential losses. The decision-makers' perception of the minefield is a critical factor. Minefields designed for psychological effect are usually placed on trade routes to stop ships from reaching an enemy nation. They are often spread thinly, to create an impression of minefields existing across large areas. A single mine inserted strategically on

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1032-472: A more extensive aerial mining campaign earlier in the war. This would have starved Japan, forcing an earlier end to the war. Naval mine A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines . Similar to anti-personnel and other land mines , and unlike purpose launched naval depth charges , they are deposited and left to wait until, depending on their fuzing , they are triggered by

1118-442: A predictable time after firing. These were still typically fired from smoothbore muzzle-loaders with a relatively large gap between the shell and barrel, and still relied on flame from the gunpowder propellant charge escaping past the shell on firing to ignite the wood fuze and hence initiate the timer. In the mid-to-late 19th century adjustable metal time fuzes, the fore-runners of today's time fuzes, containing burning gunpowder as

1204-417: A psychological weapon and as a method to sink enemy ships. Contact mines need to be touched by the target before they detonate, limiting the damage to the direct effects of the explosion and usually affecting only the vessel that triggers them. Fuze#Time In military munitions , a fuze (sometimes fuse ) is the part of the device that initiates its function. In some applications, such as torpedoes ,

1290-463: A resource-intensive and time-consuming minesweeping effort, accept the casualties of challenging the minefield, or use the unmined waters where the greatest concentration of enemy firepower will be encountered. Although international law requires signatory nations to declare mined areas, precise locations remain secret, and non-complying parties might not disclose minelaying. While mines threaten only those who choose to traverse waters that may be mined,

1376-684: A safe distance. The submarine H. L. Hunley used one to sink USS  Housatonic 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

1462-496: A safety factor previously absent. As late as World War I, some countries were still using hand-grenades with simple black match fuses much like those of modern fireworks: the infantryman lit the fuse before throwing the grenade and hoped the fuse burned for the several seconds intended. These were soon superseded in 1915 by the Mills bomb , the first modern hand grenade with a relatively safe and reliable time fuze initiated by pulling out

1548-414: A safety feature to disengage or move an arming mechanism to its armed position. Artillery shells are fired through a rifled barrel , which forces them to spin during flight. In other cases the bomb, mine or projectile has a fuze that prevents accidental initiation e.g. stopping the rotation of a small propeller (unless a lanyard pulls out a pin) so that the striker-pin cannot hit the detonator even if

1634-463: A safety pin and releasing an arming handle on throwing. Modern time fuzes often use an electronic delay system. Impact, percussion or contact fuzes detonate when their forward motion rapidly decreases, typically on physically striking an object such as the target. The detonation may be instantaneous or deliberately delayed to occur a preset fraction of a second after penetration of the target. An instantaneous "Superquick" fuze will detonate instantly on

1720-445: A series arrangement of acoustic , magnetic , and/or pressure sensors to complicate mine-sweeping efforts. The multiple safety/arming features in the M734 fuze used for mortars are representative of the sophistication of modern electronic fuzes. Safety/arming mechanisms can be as simple as the spring-loaded safety levers on M67 or RGD-5 grenade fuzes, which will not initiate

1806-567: A shipping route can stop maritime movements for days while the entire area is swept. A mine's capability to sink ships makes it a credible threat, but minefields work more on the mind than on ships. International law , specifically the Eighth Hague Convention of 1907 , requires nations to declare when they mine an area, to make it easier for civil shipping to avoid the mines. The warnings do not have to be specific; for example, during World War II, Britain declared simply that it had mined

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1892-694: A sloop mined by the Peruvians. A similar fate occurred with the gunboat schooner 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. 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

1978-604: 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 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 Loa flies when capturing

2064-503: A variable number of ships to pass unharmed before detonating. This made them a great deal harder to sweep. Mining campaigns could have devastating consequences. The U.S. effort against Japan, for instance, closed major ports, such as Hiroshima , for days, and by the end of the Pacific War had cut the amount of freight passing through Kobe – Yokohama by 90%. When the war ended, more than 25,000 U.S.-laid mines were still in place, and

2150-442: Is activated by the high acceleration of cannon launch, and the fuze must be spinning rapidly before it will function. "Complete bore safety" can be achieved with mechanical shutters that isolate the detonator from the main charge until the shell is fired. A fuze may contain only the electronic or mechanical elements necessary to signal or actuate the detonator , but some fuzes contain a small amount of primary explosive to initiate

2236-474: Is intended to activate affect the fuze design e.g. its safety and actuation mechanisms. Time fuzes detonate after a set period of time by using one or more combinations of mechanical, electronic, pyrotechnic or even chemical timers . Depending on the technology used, the device may self-destruct (or render itself safe without detonation ) some seconds, minutes, hours, days, or even months after being deployed. Early artillery time fuzes were nothing more than

2322-682: 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 for repairs. Incidents like this resulted in many of the boats that sailed to Dunkirk being degaussed in a marathon four-day effort by degaussing stations. The Allies and Germany deployed acoustic mines in World War II, against which even wooden- hulled ships (in particular minesweepers ) remained vulnerable. Japan developed sonic generators to sweep these;

2408-460: Is the practice of the removal of explosive naval mines, usually by a specially designed ship called a minesweeper using various measures to either capture or detonate the mines, but sometimes also with an aircraft made for that purpose. There are also mines that release a homing torpedo rather than explode themselves. Mines can be laid in many ways: by purpose-built minelayers , refitted ships, submarines, or aircraft —and even by dropping them into

2494-399: Is used to denote a sophisticated ignition device incorporating mechanical and/or electronic components (for example a proximity fuze for an artillery shell , magnetic / acoustic fuze on a sea mine , spring-loaded grenade fuze, pencil detonator or anti-handling device ) as opposed to a simple burning fuse . The situation of usage and the characteristics of the munition it

2580-528: The Petropavlovsk struck them near 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 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,

2666-575: The 313th Bombardment Wing to the task, with orders to plant 2,000 mines in April 1945. The mining runs were made by individual B-29 Superfortresses at night at moderately low altitudes. Radar provided mine release information. The 313th Bombardment Wing received preliminary training in aerial mining theory while their B-29 aircraft received bomb-bay modification to carry mines. Individual aircrew were then given four to eight training flights involving five radar approaches on each flight and dummy mine drops on

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2752-525: The Gulf of Finland during the Crimean War of 1853–1856. The mining of Vulcan led to the world's first minesweeping operation. During the next 72 hours, 33 mines were swept. 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

2838-584: The Korean War , mines laid by North Korean forces caused 70% of the casualties suffered by U.S. naval vessels and caused 4 sinkings. 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 SS Bridgeton was mined by Iran near Farsi Island. On 14 April 1988, USS  Samuel B. Roberts struck an Iranian mine in

2924-470: The British. In 1855, 301 more Jacobi mines were laid around Krostadt and Lisy Nos . British ships did not dare to approach them. In the 19th century, mines were called torpedoes , a name probably conferred by Robert Fulton after the torpedo fish , which gives powerful electric shocks . A spar torpedo was a mine attached to a long pole and detonated when the ship carrying it rammed another one and withdrew

3010-541: The English Channel, North Sea and French coast. Naval mines were first invented by Chinese innovators of 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 . Chinese records tell of naval explosives in the 16th century, used to fight against Japanese pirates ( wokou ). This kind of naval mine

3096-673: The French; they planted nine torpedo mines in the river and blocked the entrance. During the Boxer Rebellion , Imperial Chinese forces deployed a command-detonated mine field at the mouth of the Hai River before the Dagu forts , to prevent the western Allied forces from sending ships to attack. The next major use of mines was during the Russo-Japanese War of 1904–1905. Two mines blew up when

3182-608: The German ZUS40 anti-removal bomb fuze. A fuze must be designed to function appropriately considering relative movement of the munition with respect to its target. The target may move past stationary munitions like land mines or naval mines; or the target may be approached by a rocket, torpedo, artillery shell, or air-dropped bomb. Timing of fuze function may be described as optimum if detonation occurs when target damage will be maximized, early if detonation occurs prior to optimum, late if detonation occurs past optimum, or dud if

3268-655: The Navy proved unable to sweep them all, limiting efforts to critical areas. After sweeping for almost a year, in May 1946, the Navy abandoned the effort with 13,000 mines still unswept. Over the next thirty years, more than 500 minesweepers (of a variety of types) were damaged or sunk clearing them. The U.S. began adding delay counters to their magnetic mines in June 1945. Since World War II , mines have damaged 14 United States Navy ships, whereas air and missile attacks have damaged four. During

3354-536: 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. Clearing the barrage after the war took 82 ships and five months, working around the clock. It was also during World War I, that the British hospital ship , HMHS  Britannic , became the largest vessel ever sunk by a naval mine . The Britannic

3440-693: The Russian minelayer Amur planted a 50-mine minefield off Port Arthur and succeeded in sinking the Japanese battleships Hatsuse and Yashima . 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) . Many early mines were fragile and dangerous to handle, as they contained glass containers filled with nitroglycerin or mechanical devices that activated

3526-467: 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

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3612-579: The United States submarine campaign . Eventually most of the major ports and straits of Japan were repeatedly mined, severely disrupting Japanese logistics and troop movements for the remainder of the war with 35 of 47 essential convoy routes having to be abandoned. For instance, shipping through Kobe declined by 85%, from 320,000 tons in March to only 44,000 tons in July. Operation Starvation sank more ship tonnage in

3698-402: The approach of or contact with any vessel. Naval mines can be used offensively, to hamper enemy shipping movements or lock vessels into a harbour ; or defensively, to create "safe" zones protecting friendly sea lanes, harbours, and naval assets. Mines allow the minelaying force commander to concentrate warships or defensive assets in mine-free areas giving the adversary three choices: undertake

3784-499: 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. In response the U.S., Britain, France, and three other nations launched Operation Intense Look , a minesweeping operation in the Red Sea involving more than 46 ships. On

3870-676: 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". Ukrainian forces have mined "from the Sea of Azov to the Black Sea which banks the critical city of Odesa." Naval mines may be classified into three major groups; contact, remote and influence mines. The earliest mines were usually of this type. They are still used today, as they are extremely low cost compared to any other anti-ship weapon and are effective, both as

3956-556: The commander of Japan's mine sweeping operations noted that he thought this mining campaign could have directly led to the defeat of Japan on its own had it begun earlier. Similar conclusions were reached by American analysts who reported in July 1946 in the Strategic Bombing Survey that it would have been more efficient to combine the United States' effective anti-shipping submarine effort with land- and carrier-based air power to strike harder against merchant shipping and begin

4042-524: The correct order. As an additional safety precaution, most modern nuclear weapons utilize a timed two point detonation system such that ONLY a precisely firing of both detonators in sequence will result in the correct conditions to cause a fission reaction Note: some fuzes, e.g. those used in air-dropped bombs and landmines may contain anti-handling devices specifically designed to kill bomb disposal personnel. The technology to incorporate booby-trap mechanisms in fuzes has existed since at least 1940 e.g.

4128-563: The crew can choose which effect fuze will suit target conditions that may not have been known before the flight. The arming switch is set to one of safe , nose , or tail at the crew's choice. Base fuzes are also used by artillery and tanks for shells of the 'squash head' type. Some types of armour piercing shells have also used base fuzes, as have nuclear artillery shells. The most sophisticated fuze mechanisms of all are those fitted to nuclear weapons , and their safety/arming devices are correspondingly complex. In addition to PAL protection,

4214-577: 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 U.S. Army Corps of Engineers , which trained officers and men in their use at the Engineer School of Application at Willets Point, New York (later named Fort Totten ). In 1901 underwater minefields became

4300-407: The delay mechanism became common, in conjunction with the introduction of rifled artillery. Rifled guns introduced a tight fit between shell and barrel and hence could no longer rely on the flame from the propellant to initiate the timer. The new metal fuzes typically use the shock of firing ("setback") and/or the projectiles's rotation to "arm" the fuze and initiate the timer : hence introducing

4386-406: The detonation. Fuzes for large explosive charges may include an explosive booster . Some professional publications about explosives and munitions distinguish the "fuse" and "fuze" spelling. The UK Ministry of Defence states ( emphasis in original): Historically, it was spelled with either 's' or 'z', and both spellings can still be found. In the United States and some military forces, fuze

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4472-589: The disadvantage of "sweeping" only a small strip. A better solution was found in the "Double-L Sweep" 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

4558-521: The explosion. Ships that had successfully run the gantlet of the Atlantic crossing were sometimes destroyed entering freshly cleared British harbours. More shipping was being lost than could be replaced, and Churchill ordered the intact recovery of one of these new mines to be of the highest priority. The British experienced a stroke of luck in November 1939, when a German mine was dropped from an aircraft onto

4644-441: The explosive train so long as the pin is kept in the grenade, or the safety lever is held down on a pinless grenade. Alternatively, it can be as complex as the electronic timer-countdown on an influence sea mine, which gives the vessel laying it sufficient time to move out of the blast zone before the magnetic or acoustic sensors are fully activated. In modern artillery shells, most fuzes incorporate several safety features to prevent

4730-557: The failed "floating petard". Weapons of this type were apparently tried by the English at the Siege of La Rochelle in 1627. American David Bushnell developed the first American naval mine, for use against the British in the American War of Independence . 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

4816-502: The first to be so fitted were the carrier HMS  Ark Royal 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. This was felt to be impractical for smaller warships and merchant vessels, mainly because

4902-537: The force were several fireships , carrying 40 barrels of gunpowder and rigged to explode by a clockwork mechanism. 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

4988-535: The fuze of the naval mine. Although this is the rotating steel wheel's first use in naval mines, Jiao Yu described their use for land mines in the 14th century. 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. The Dutch inventor Cornelius Drebbel was employed in the Office of Ordnance by King Charles I of England to make weapons, including

5074-433: The fuzing used in nuclear weapons features multiple, highly sophisticated environmental sensors e.g. sensors requiring highly specific acceleration and deceleration profiles before the warhead can be fully armed. The intensity and duration of the acceleration/deceleration must match the environmental conditions which the bomb/missile warhead would actually experience when dropped or fired. Furthermore, these events must occur in

5160-475: The gear was not ready by war's end. 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. 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

5246-718: 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

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5332-500: 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 rubles ) 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

5418-399: The last flight. Beginning on 27 March 1,000 parachute-retarded influence mines with magnetic and acoustic detonators were initially dropped, followed by many more, including models with water pressure displacement detonators. This mining proved the most efficient means of destroying Japanese shipping during World War II. In terms of damage per unit of cost, it surpassed strategic bombing and

5504-460: The last six months of the war than the efforts of all other sources combined. The Twentieth Air Force flew 1,529  sorties and laid 12,135 mines in 26 fields on 46 separate missions. Mining demanded only 5.7% of the XXI Bomber Command's total sorties, and only 15 B-29s were lost in the effort. In return, mines sank or damaged 670 ships totaling more than 1,250,000 tons. After the war,

5590-442: The latest activation of the individual components. Series combinations are useful for safety arming devices, but increase the percentage of late and dud munitions. Parallel fuze combinations minimize duds by detonating at the earliest activation of individual components, but increase the possibility of premature early function of the munition. Sophisticated military munition fuzes typically contain an arming device in series with

5676-404: The majority of the fleet then underwent a massive 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

5762-454: 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

5848-494: The mine. The mine detected this loss of the magnetic field which caused it to detonate. The mechanism had an adjustable sensitivity, calibrated in milligauss . 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

5934-491: 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 . They disarmed

6020-583: The munition fails to detonate. Any given batch of a specific design may be tested to determine the anticipated percentage of early , optimum . late , and dud expected from that fuze installation. Combination fuze design attempts to maximize optimum detonation while recognizing dangers of early fuze function (and potential dangers of late function for subsequent occupation of the target zone by friendly forces or for gravity return of anti-aircraft munitions used in defense of surface positions.) Series fuze combinations minimize early function by detonating at

6106-710: The orders of the Reagan administration , the CIA mined Nicaragua 's Sandino port in 1984 in support of the Contras . A Soviet tanker was among the ships damaged by these mines. 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. During the Gulf War , Iraqi naval mines severely damaged USS  Princeton and USS  Tripoli . When

6192-711: The possibility of activating a mine is a powerful disincentive to shipping. In the absence of effective measures to limit each mine's lifespan, the hazard to shipping can remain long after the war in which the mines were laid is over. Unless detonated by a parallel time fuze at the end of their useful life, naval mines need to be found and dismantled after the end of hostilities; an often prolonged, costly, and hazardous task. Modern mines containing high explosives detonated by complex electronic fuze mechanisms are much more effective than early gunpowder mines requiring physical ignition. Mines may be placed by aircraft, ships, submarines, or individual swimmers and boatmen. Minesweeping

6278-677: The project as "not fair and honest warfare". In 1854, during the unsuccessful attempt of the Anglo-French (101 warships) fleet to seize the Kronstadt fortress, British steamships HMS  Merlin (9 June 1855, the first successful mining in Western history), HMS  Vulture 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 , in

6364-854: 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 . 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) . During the War of the Pacific (1879-1883), the Peruvian Navy , at

6450-596: The sensor used, the pre-set triggering distance is calculated such that the explosion will occur sufficiently close to the target that it is either destroyed or severely damaged. Remote detonators use wires or radio waves to remotely command the device to detonate. Barometric fuzes cause a bomb to detonate at a certain pre-set altitude above sea level by means of a radar , barometric altimeter or an infrared rangefinder . A fuze assembly may include more than one fuze in series or parallel arrangements. The RPG-7 usually has an impact (PIBD) fuze in parallel with

6536-440: 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 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

6622-455: The slightest physical contact with the target. A fuze with a graze action will also detonate on change of direction caused by a slight glancing blow on a physical obstruction such as the ground. Impact fuzes in artillery usage may be mounted in the shell nose ("point detonating") or shell base ("base detonating"). Proximity fuzes cause a missile warhead or other munition (e.g. air-dropped bomb or sea mine ) to detonate when it comes within

6708-462: 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/apocryphal command during the Battle of Mobile Bay in 1864, " Damn the torpedoes, full speed ahead! " refers to a minefield laid at Mobile , Alabama. After 1865 the United States adopted the mine as its primary weapon for coastal defense . In

6794-552: The war concluded, eight countries conducted clearance operations. Houthi forces in the Yemeni Civil War have made frequent use of naval mines, laying over 150 in the Red Sea throughout the conflict. 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

6880-521: The weapon is dropped on the ground. These types of fuze operate with aircraft weapons, where the weapon may have to be jettisoned over friendly territory to allow a damaged aircraft to continue to fly. The crew can choose to jettison the weapons safe by dropping the devices with safety pins still attached, or drop them live by removing the safety pins as the weapons leave the aircraft. Aerial bombs and depth charges can be nose and tail fuzed using different detonator/initiator characteristics so that

6966-674: Was the sister ship of the RMS Titanic , and the RMS ; Olympic . 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

7052-402: 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

7138-690: Was equal to 14 kg (31 lb) 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 Alexander ( Kronstadt ), to deter the British Baltic Fleet from attacking them. It gradually phased out its direct competitor the Nobel mine on

7224-459: Was further disguised by wearing dark clothes and a black cap. 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. 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. Also included in

7310-468: Was loaded in a wooden box, sealed with putty . General Qi Jiguang made several timed, drifting explosives, to harass Japanese pirate ships. 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

7396-462: Was used on the Delaware River as a drift mine, destroying a small boat near its intended target, a British warship. 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

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