Possibly the first water mine in the world with a target-fired trigger (as opposed to earlier ones which had simple, slow-burning fuzes) was invented by David Bushnell, the man who is most famous for inventing a one-man submersible, the Turtle. Like the Turtle, these sea mines were unsuccessful when they were used against the British fleet in Philadelphia during January 1778, although the resulting "Battle of the Kegs" did cause a few casualties and inspired a well-known Revolutionary War poem.
For most of the 19th century the US Army was responsible for the development and use of mines, as mines were considered to be defensive weapons that were useful for protecting harbors and coastal waters. The Confederate Navy used mines, or torpedoes, as they were then called, quite extensively during the American Civil War, and sank approximately 27 Federal vessels and damaged many more. By comparison, only nine Federal vessels were sunk by gunfire. Many different kinds of mines were used by the Confederates, with one of the most effective being the frame torpedo, which was a large nose-fuzed artillery shell that was mounted on a wooden frame and located where a ship might strike it.
Not until late in the 19th century did the Navy start to take any interest in these weapons, but none were used during the Spanish-American War of 1898 and it was not until the Russo-Japanese War of 1905 that this interest became serious. During that war, both Imperial Russia and Japan had some success with their naval mines, which prompted the US Navy to ask Congress for funds for a mine depot ship. The old cruiser USS San Francisco (C-5) was converted in 1912 and she became the first mine warfare ship in the US Navy.
The first mines procured by the Navy were originally called "Naval Defense Mines" and were either purchased from European powers or were copies of European designs. Progress on mines was considered satisfactory prior to the start of World War I, but with the US entry into the war it was discovered that British mines of the same general types had proved unreliable. Bureau of Ordnance reports of 1917 declared that the status of mining in the USN with these Naval Defense Mines was "very unsatisfactory" and recommended development of new types, which led to the Mark 5 contact mine and the Mark 6 antenna mine.
These Naval Defense Mines were all declared obsolete in 1930 and removed from inventory. None of these designs were very successful, so perhaps it is surprising that it took so long to take them out of service.
The first USA designed mine, the Mark 5, was of the "Horned" type. Horns were made of soft metal such as lead and held a glass ampoule containing battery acid, usually potassium-bichromate. The lower end of the horn contained an electric battery minus the electrolyte. Contact with the horn broke open the acid container, energizing the battery which then heated a platinum wire in a mercury fulminate detonator, thus exploding the mine. By definition, this was a weapon with limited range and fields needed to be densely packed in order for it to be effective against shipping. However, such close-laid fields ran the risk of one mine setting off adjacent mines as fraternal kills.
The "K-pistol" of the Mark 6 used a copper antenna which extended upwards to just below the surface. This was connected by a relay to a copper plate on the outside of the mine. Seawater acted as the electrolyte of a battery which would be formed when a ship with a steel hull approached and touched the antenna. The current running down the antenna operated the relay and exploded the mine. This method allowed each mine to cover a wider area, meaning that fewer mines could be used to cover a given area than with the horn type. In modern terms, the "K" device exploited the Underwater Electric Potential (UEP) effect.
Magnetic triggers were originally only used on ground (bottom) mines. This is because, if they were moored, the changing of the magnetic field as they rose and fell with the tide would set them off. Near the end of World War II, a trigger that measured the total field around the mine was developed. This device added up the fields in such a way that the tides did not affect it.
Acoustic mines measure sound of certain frequencies, usually those of propeller, engine and sonar noises.
Pressure detector fuzes measure the pressure wave created by a ship moving through the water. These were simultaneously developed by both Germany and the USA during World War II, but both held off deploying them for fear that the technology would be captured by the other side. They were first used in combat off the Normandy beaches and were heavily used against the Japanese home islands near the end of the war.
|USS Terror CM-5||800 mines|
|USS Gamble DM-15 class (ex-flush deckers)||80 mines|
|USS Robert H. Smith DM-23 class (ex-Allen Sumners)||100 mines|
|USS Argonaut SS-166||80 mines|
The table shows mine outfits as given in "US Warships of World War II" by Paul Silverman. Other sources differ, but I believe that these are the "official" numbers.
There were also some ex-mercantiles and former Army "mine-planters" listed, but no mine outfit numbers are given for these ships. However, USS Salem CM-11 is recorded as having laid 202 mines off Casablanca on 27 and 28 December 1942. USS Argonaut SS-166 was converted to a transport submarine immediately following the attack on Pearl Harbor and apparently never laid a mine under combat conditions.
The widely used and long-lived (1917 to ca. 1985) Mark 6 "K-pistol" mine was relatively easy to deploy and did not require specialized minelayers. See the picture below of USS Ute ATF-6 (a tug) being used to launch one of these mines. This ease of use by non-specialized mine ships is one of the reasons that there were so few dedicated mine-layers in the USN and why many of the smaller coastal minelayers were converted for other duties.
Conventional submarines were also used as minelayers. In 1943, they could carry eleven Mark 10 or Mark 12 mines in place of three torpedoes and many mini-minefields were laid as a result, some quite effectively. But the most common mine-layers during World War II were aircraft.
After World War II, aircraft have been the predominant US minelayers, as shown in the tables below. There are a few submarine-launched mines in the inventory, with at least one new one, ISLMM (see below) currently under development.
United States ships planted 56,611 mines and the British laid an additional 16,300 as part of the North Sea Mine Barrage. These sank at least six U-boats and damaged another half-dozen seriously enough that they were forced to return to base. It has been suggested that the cost / benefit ratio of the Barrage was grossly in favor of the Germans.
As far as is known, no enemy ship was sunk by the approximately 20,000 mines used in defensive minefields placed in US waters.
US submarines planted a total of 576 Mark 12 mines and 82 Mark 10 mines in 36 fields. Of these, 421 mines planted in 21 of the fields sank 27 ships of about 63,000 tons and damaged 27 more of approximately 120,000 tons. See US Submarine Mining Success for other information.
Avenger and Ventura aircraft could carry a single mine and in 1944 Avengers closed Palau harbor by mining the entrances. They then sank all 32 ships in the harbor with conventional bombs and torpedoes. A total of approximately 100 ships were sunk or badly damaged in the Pacific during the war by mines laid by Navy aircraft.
By 1945, the Army Air Force was devoting considerable resources to the mining role, with 80 to 100 B-29s based at Tinian being used to mine the home waters around Japan. These B-29s could carry seven 2,000 lbs. (907 kg). or twelve 1,000 lbs. (454 kg) mines. Starting in March 1945 and continuing until early August, 4,900 magnetic, 3,500 acoustic, 2,900 pressure and 700 low-frequency mines were laid. These mines sank 294 ships outright, damaged another 137 beyond repair and damaged a further 239 that could be repaired. In cargo tonnage, the total was 1.4 million tons which was about 75% of the shipping available in March 1945.
Between January and March 1945, B-29s also closed the approaches to Singapore, Saigon and Camranh Bay harbors by magnetic mining.
|Army Controlled Mine
for Harbor Defense
|Navy Mark 5||Moored Hertz Horn||2,000|
|Navy Mark 6||Moored Antenna||59,000|
|Navy Mark 10||Moored Hertz Horn
(planted from 21-inch torpedo tube)
|Navy Mark 11||Moored Antenna
(planted from 40-inch tube - USS Argonaut)
|Navy Mark 12||Ground Magnetic
(planted from 21-inch tube)
|Navy Mark 12||Ground Magnetic
(planted by aircraft)
|Planting Craft||Make of Mine||Type of Mine|
|US Navy, Defensive||18,884||---||18,884||---||---||---||18,884|
|US Navy, Offensive||2,871||---||2,859||---||---||12||2,871|
|US Navy, Aircraft||662||---||---||575||54||33||662|
|US Army, Outer Zone||1,665||182||268||1,397||182||---||1,847|
|AAF, Inner Zone||12,135||---||---||4,921||4,255||2,959||12,135|
British Vickers design. Spherical mine about 30 inches (76 cm) in diameter with a 120 lbs. (54 kg) TNT burster. Used a protruding float made of cork, 3 feet (0.91 m) long, for inertia ignition - contact with a ship made the mine rotate relative to the float. Launched from trolley rails. Production started around 1915 and by 1917 the Portsmouth Navy Yard was manufacturing 140 of these per week with plans to ramp up production to 500 per week.
Spherical antenna type using a K-type pistol, 34 inches (87 cm) in diameter. This mine was designed specifically for the North Sea Mine Barrage of World War I. However, as shown above, it was still being used operationally as late as 1978. On 17 October 1917, the Secretary of the Navy authorized the construction of 100,000 mines of this type at a cost of $40,000,000 (40 million dollars). By the early summer, these were being produced at a rate of 1,000 a day with a peak of 1,500 being produced in one 24 hour period. In order to support this rate of manufacture, the Navy built its own TNT factory at St. Julien's Creek, Virginia, capable of producing 300,000 lbs. (136,000 kg) of TNT per day.
The Mark 6 was very successful and remained in US inventories until about 1985, making it the USA's longest-lived mine. 1,400 lbs. (635 kg) total, charge of 300 lbs. (136 kg) TNT. Could be moored in waters up to 3,000 feet (914 m) deep. Three safety devices were employed, one a time delay, one a hydrostatic which held a switch open until the mine had sunk several feet underwater and the third to keep the explosive steps open until the mine had reached a considerable depth. Mod 2 was a rising type, Mod 3 had a Mark 9 case with a 100 foot (30 m) lower antenna. Mod 4 had a Mark 6 case with a 50 foot (15 m) lower antenna. All of these had a few Hertz (acid) horns as a backup firing mechanism. Early units used in the North Sea Barrage had reliability problems, with 4 to 8 percent firing shortly after being planted.
Moored contact mine for firing from 21 inch (53.3 cm) torpedo tubes. This project was started in 1921, halted for a time, and then resumed. 1,760 lbs. (798 kg) total, charge of 300 lbs. (136 kg). Mod 1 was contact fired, Mod 2 was cancelled, Mod 3 was magnetic and weighed 1,800 lbs. (816 kg) with a charge of 420 lbs. (190 kg) of TNT. Mod 5 was an aircraft dropped version of Mod 2, cancelled. Mod 6 and 8 were parachute versions of Mod 3 and were replaced by Mod 9, all of these weighed 1,850 lbs. (839 kg) with a charge of 420 lbs. (190 kg) of TNT. Mod 7 was Mod 3 modified for PT boat launch. Mod 11 was a moored contact mine specifically developed for the USS Argonaut SS-475 and weighed 1,900 lbs. (862 kg) with a charge of 500 lbs. (227 kg) TNT.
K-type pistol mine specifically developed for the USS Argonaut SS-475 and weighed 1,875 lbs. (850 kg) with a charge of 500 lbs. (227 kg) TNT. Argonaut had special 40 inch (102 cm) tubes for launching these mines and could carry 65 to 70. However, she never laid any of these during the war, as she was redesigned early in 1942 as a cargo carrier and was sunk in 1943 by the Japanese.
Submarine launched mine. Cylindrical with an aluminum case, this mine was developed in the 1920s from German S-type mines. Dimensions were 20.8D x 94.25L inches (52.8 x 239.4 cm). Weighed 1,445 lbs. (655 kg) with a 1,100 lbs. (499 kg) TNT charge or 1,595 lbs. (723 kg) with a 1,250 lbs. (567 kg) Torpex charge. Mod 1 was parachute mine, Mod 3 was a submarine type and Mod 4 was a replacement for Mod 1. Some of these mines were delivered to Manila just before the start of World War II. They were dropped into deep water to prevent capture.
Anti-sweep mine. Anchored with a moored float and a small explosive charge. Total 1,125 lbs. (510 kg) with a 2 lbs. (0.9 kg) charge (not a misprint). In service 1944.
Note: Anti-sweep mines are usually scattered in a mine field along with normal moored mines. Anti-sweep mines are designed to have a very small positive buoyancy. When the wire of a mine sweeper hits the mooring wire of the anti-sweep mine, the anti-sweep mine will sink down until it hits the sweep wire. The anti-sweep mine will then detonate and cut the sweeping wire, thus ending the sweeping operation.
Aircraft laid magnetic mine. Mod 1 had A5 acoustic trigger, Mod 2 had A6 pressure trigger and Mod 3 also had an acoustic trigger. Depending upon the flight gear, these were 22.4D x 87.2-93L inches (56.9D x 221.5-236L cm) and weighed 1,950-2,000 lbs. (885-907 kg) with a charge of 1,274 lbs. (578 kg) Torpex, HBX or TNT.
An improved Mark 26 Mod 1 with a larger explosive charge and a slanted nose for improved underwater trajectories. Total 1,024 lbs. (464.5 kg) with TNT charge of 570 lbs. (258.5 kg) or 1,082 lbs. (490.8 kg) with Torpex charge of 638 lbs. (289.4 kg). Magnetic fuzed using a MM2 exploder. Basic version was acoustic, Mods 2 was a low-frequency acoustic and Mod 3 was pressure activated.
1,000 lbs. (454 kg) ground mine of new design series. Mod 1 acoustic fuzed, Mod 2 magnetic, Mod 3 combined pressure and magnetic, Mod 4 was not issued, Mod 5 combined acoustic and magnetic, Mod 6 combined acoustic, magnetic and pressure. All variants are 18.8D x 70.2L inches (48 x 178 cm). Weights are respectively 1,130 lbs. (513 kg), 1,170 lbs. (531 kg), 1,190 lbs. (540 kg), 1,200 lbs. (544 kg) and 1,235 lbs. (560 kg). Charge for all was 625 lbs. (284 kg) HBX-1. All Mods use identical mine cases and removable instrument racks so that the firing assemblies can be stored apart from the explosives.
Air launched 2,000 lbs. (907 kg) class bottom mine. 23.4D x 89.9L inches (59D x 228L cm). Mods 1 through 6 correspond to Mark 52 Mods 1 through 6 except for the weight. Mod 7 is unique to the Mark 55 and used an improved dual-channel magnetic firing mechanism. Weights were respectively 2,039 lbs. (925 kg), 2,110 lbs. (957 kg), 2,120 lbs. (962 kg), 2,119 lbs. (961 kg), 2,128 lbs. (965 kg) and 2,118 lbs. (961 kg).
Air launched 2,000 lbs. (907 kg) class moored mine. 22.4D x 114.3L inches (56D x 290L cm). Actual weight 2,135 lbs. (968 kg) with a charge of 360 lbs. (163 kg) HBX-3. First deployed in 1966 and still active as of 2001. Similar to the submarine launched Mark 57. Uses a "Total Field" magnetic exploder.
CAPTOR (encapsulated torpedo mine). Uses Mark 46 Mod 4 torpedo with aluminum case. Can be launched by aircraft, surface ships or submarines. Uses Reliable Acoustic Path (RAP) sound propagation method to detect target ships and designed to be used in deep water. First deployed in 1979 and still active as of 2001.
Aircraft / Ship laid: 21 x 145 inches (53 x 368 cm) (includes length of parachute).
Submarine laid: 21 inches x 132 inches (53 x 335 cm).
Weight: Air / Ship laid: 2,370 lbs. (1,077 kg); Submarine laid: 2,056 lbs. (935 kg).
Conversion of Mark 82 [500 lbs. (227 kg)] bomb. Superseded Destructor EX-52. Marks 62, 63 and 64 are known as the "Quickstrike" series and have a variable influence target designation system that can be used against either land or sea targets. Quickstrike was conceived as a new series of ground mines, replacing the ones that had become compromised as a result of the Vietnam War. These new mines use the same design concept as do "smart" bombs, that is, they are simple bolt-on additions to a standard air-dropped bomb. Quickstrike's design emphasizes ease of maintenance and ease of mine preparation for use. For example, the older mines required refrigeration of their batteries to prolong life, the Quickstrikes do not.
The latest in the "Quickstrike" series, but this weapon is not a bomb conversion and was first deployed in 1983. Magnetic/seismic/pressure target detection devices (TDDs) are used on various models.
Dimensions: 29 inches (across the fins) x 128 inches (74 x 325 cm)").
Weight: 2,390 pounds (1,086 kg)
Submarine Launched Mobile Mine (SLMM) with magnetic/seismic or magnetic/seismic/pressure triggers. Converted from Mark 37 torpedo. Introduced into service in 1987.
Dimensions: 19 x 161 inches (48.5 x 409 cm).
Weight: 1,658 lbs. (754 kg).
Explosives: 510 lbs. (230 kg) of high explosive.
This is a joint effort between the United States Navy and the Royal Australian Navy intended to replace the obsolescent Mark 67 SLMM (see above). The program would convert Mark 48 torpedoes into dual warhead mobile mines.
Each dual warhead would be equipped with the Target Detection Device (TDD) Mark 71. The TDD Mark 71 provides advanced mine algorithms for ship detection, classification and localization against some of the emerging threats (i.e., quiet diesel-electric submarines, mini-subs, fast patrol boats, air cushioned vehicles) that are likely to be encountered in future conflicts.
The ISLMM would retain the propulsion and wire-guidance of the Mark 48, thus allowing this torpedo/mine to be launched from a remote location and then guided to its destination. Each warhead may be dropped in a separate location, allowing ISLMM to attack two separate targets. ISLMM fits into any standard 21 inch (53.3 cm) torpedo tube and may be launched from any submarine so equipped.
Drifting Mines were intended to be launched by surface ships or submarines against a pursuing enemy ship. Mark 1 through Mark 6 were designed between 1915 and 1925. Mark 7 was designed in 1942.
Destructor mines (DST) were developed during the Vietnam War. These were Mark 80-series GP bombs converted to mines by the addition of mine-type arming, detection and filling systems. They differ from conventional sea mines in that they can be used against land targets as well as sea targets. The Mark 36, 40 and 41 Destructors were respectively the Mark 82 [500 lbs. (227 kg)], Mark 83 [1,000 lbs. (454 kg)] and Mark 84 [2,000 lbs. (907 kg)] bombs. Arming, detection and firing were common to all three types.
Other Destructor Mark numbers were assigned to self-destruction charges. The Destructor designation for these bomb conversions were probably intended as a security cover for what was a secret program during the war.
- "America's Use of Sea Mines" by Robert C. Duncan, Ph.D.
- "US Naval Weapons" and "The Naval Institute Guide to World Naval Weapon Systems 1991/92" both by Norman Friedman
- "Damn the Torpedoes: A Short History of U.S. Naval Mine Countermeasures, 1777 - 1991" by Tamara Mosere Melia
- "US Warships of World War II" by Paul Silverstone