mine warfare.

1. Land mines

Until 1939 mine warfare on land meant mining and counter-mining under the walls of fortresses or fortified fronts to blow breaches in them. The advent of the tank, which restored mobility to armies by neutralizing the lethal combination of barbed wire and machine-guns, gave the term a new dimension. Anti-tank mines and guns were introduced, bringing naval-style mine warfare into the land environment. But anti-tank mines laid on land could be detected and lifted more easily than at sea, unless they were covered by fire or protected by some other means. Consequently, anti-personnel mines were developed to make mine-lifting hazardous, particularly at night when covering fire was less effective.

The Germans had used a primitive form of anti-tank mine in 1918, consisting of an artillery shell fitted with a pressure fuze, and all armies developed their own versions in the inter-war years. The first anti-tank mines to be used operationally were the Italian bar-mines laid in 1940 during the Western Desert campaigns. These were 91 cm. (36 in.) long and 12.7 cm. (5 in.) square in cross-section, contained 3 kg. (7 lb.) of explosive, and were actuated by pressure on the lid. Their anti-personnel mines were stick grenades, triggered by either trip-wires or pressure fuzes.

The British developed a small circular and over-complex anti-tank mine to exacting ammunition safety standards, but they had not produced it in quantity before the fall of France in June 1940. Faced with imminent invasion by German panzer forces, they abandoned stringent safety requirements and adapted a commercial cake tin, filled it with 3.6 kg. (8 lb.) of TNT (see explosives), and fitted it with a simple pressure fuze. The Mark IV, as it was called, was later found to be over-susceptible to blast. It was replaced by the Mark V with redesigned fuzing to make it less vulnerable to explosive clearance devices. The British did not produce an anti-personnel mine, preferring to depend upon covering their minefields by fire.

The Germans developed their excellent circular Tellermine, weighing 8.6 kg. (19 lb.), filled with 5 kg. (11 lb.) of TNT and fitted with a pressure fuze. They also provided themselves with jumping anti-personnel mines, the S-Mine (Springenmine), which was buried with only the small prongs of the trigger mechanism visible. When actuated, a shrapnel-filled canister was blown upwards from the mine's casing, rising to about chest height before exploding with lethal effect. The Teller and S-Mines were first brought into service in the Western Desert campaigns around Tobruk in 1941.

At the start of the German–Soviet war the USSR suffered a critical shortage of mines as the Main Military Engineering Administration had been neglected during the 1930s. Also, because mines were defensive weapons, they were not politically acceptable and were thought to be the weapon of the ‘weak’. This policy was eventually reversed but in early 1941 the Red Army had only one million anti-tank mines—just over a third of what was required for half a year's operations—and no other types at all. This shortage, exacerbated by having to defend terrain void of any natural defences against tanks, meant that improvised mines had to be made. These often had hardly any metal content, being mainly constructed of wood, glass, or even tarred cardboard, and infantrymen often had to resort to using the Molotov cocktail against German armour. But once the Red Army had more mines of different types its engineers employed them cleverly and used them in massive quantities. It has been claimed that by the end of the war the Red Army had laid 200 million mines.

Mines were laid in their millions during the war, mostly in the Western Desert campaigns and on the Eastern Front. The density for laying them varied; the British laid their anti-tank mines one for every yard of front. There was less call for them in the Pacific and South-East Asian theatres where jungle conditions inhibited armoured warfare, but the American and Japanese had mines similar to the German versions available. On Okinawa Japanese minefields held up one US division for a week.

Mines were far easier to lay than to detect and clear. Laying was largely a problem of logistics, transport, and manpower. All mines had to be dug in by hand as neither side managed to develop a successful mechanical minelayer during the war. They were usually laid in fields some 460 m. (500 yd.) deep in staggered rows, which both reduced a tank's chances of driving through unscathed and made detection and clearance as protracted as possible.

But mines proved two-edged weapons. If minefields were not clearly marked with perimeter wire and warning signs, and their location and layouts accurately recorded, one's own side could blunder into them, and lifting them later could become a dangerous task. Marking minefields, in fact, increased their deterrent value, and made laying dummy minefields an effective ploy (see also deception).

A struggle between detection and counter-detection, and between clearance and counter-clearance, soon began, just as it did at sea. At first, mines could only be found by laborious prodding with bayonets or metal probes, and they had to be lifted by hand, usually by stealth at night or behind an artillery barrage. By 1942, hand-held electronic mine detectors had been developed, but they were far from reliable.

The bulk of mine-laying, breaching, and clearance was carried out by engineers. All arms were trained in the rudiments of mine warfare to help them to look after themselves and to reduce calls on engineers. But on the Eastern Front the Red Army—which, especially early on, had rudimentary mine-clearing equipment and a shortage of engineers—was ruthless in using untrained infantrymen to clear a path through a minefield; and it has been said—though it is probably apocryphal—that it was the specific task of penal battalions to do so by simply walking across them.

The British developed a number of mine clearance devices fitted to tanks such as indestructible rollers and mine ploughs, which were later adopted and adapted by the Americans who called them ‘Earthworms’ and ‘Aunt Jemimas’. The most successful were the flail tanks called ‘Crabs’ and ‘Scorpions’. They were standard gun-tanks fitted with rotating drums driven off their engines, from which weighted chains flailed paths through minefields. The early marks were mechanically unreliable, but they played a useful part in Allied operations from the second battle of El Alamein onwards (see also engineers, Figures 1–4).

Blast clearance devices were also developed by the Allies such as explosive-filled steel pipes, called Snakes (see alsoBangalore torpedo), pushed through minefields by tanks. Most anti-personnel mines could be cleared by the blast, but some anti-tank mines were left unscathed. Later versions of the German Tellermine were blast resistant, a precaution the British had developed as early as 1941. To combat this the Americans developed a bomb-firing tank (T12) whose missiles exploded above the mines which were detonated by the pressure caused by the explosions.

By 1943 the Axis were beginning to use non-metallic mines to defeat the Allied mine-detectors. They were mostly cheap and easy to produce wooden box mines with plastic pressure fuzes for anti-tank and anti-personnel purposes. The German wooden anti-personnel Schuh-mine proved highly successful. It was a wooden box with just enough explosive to take a man's foot off, and yet small enough to be difficult to spot. It maimed many a senior officer looking for an observation point, as well as taking a toll of attacking infantry. The Germans also made greater use of anti-handling devices. For instance, their Tellermine was fitted with screw sockets on the side and underneath to take various types of anti-lifting device, and anti-handling fuzes were issued.

As the pace of German withdrawals quickened in 1944, and their commanders saw less likelihood of returning to an area, they discontinued marking minefields, and mines were sown at random to harass the Allied advance.

While the mine never managed to reverse the success of the tank in restoring mobility to land battlefields, it did reduce the dominance which armoured formations had enjoyed in the early phases of the Second World War. Between 20% and 30% of all tank casualties were caused by mines. See also limpet mines.

William Jackson

2. Sea mines

In use since the 1840s, sea mines were employed by both sides, minefields being laid both defensively for protection and offensively to inflict shipping casualties. About 500,000 mines were laid during the course of the war. They did not sink nearly as many warships, or merchantmen, as did aircraft or submarines—only 6.5% of all Allied merchant shipping was sunk by mines—but their influence on the conduct of the war at sea was great. German mines closed British and US ports for days at a time, and played a major role in imposing the Axis siege of Malta; a Finnish minefield in the Baltic Sea crippled the Soviet Red Banner Fleet in August 1941; British mines damaged German surface raiders in February 1942 (see CERBERUS); and, though it was US submarines which enforced the blockade of Japan, it was minefields laid from the air that finally severed its supply routes.

The moored contact mine was the one most commonly employed by both sides and, despite the introduction of the magnetic, acoustic (sonic), and pressure mines, known generically as influence mines (see below), it remained the biggest hazard because of the huge quantities laid. A spherical ball, it was fitted with horns and filled with 272 kg. (600 lb.) of explosives. When one of the horns was fractured by contact with a ship's hull a chemical was released which activated the firing mechanism. It was usually laid in waters not exceeding 180 m. (600 ft.) in depth—though the Japanese had ones that could be laid in depths up to 1,100 m. (3,500 ft.)—and was moored by a cable attached to a heavy weight on the sea bottom. It was laid by specialist minelaying vessels but also by a variety of warships, including auxiliary cruisers.

Influence mines, cylindrical in shape, containing as much as 350 kg. (775 lb.) of explosives, were usually dropped by parachute from aircraft. This meant flying vulnerably low to obtain accuracy, but from January 1944radar enabled Allied aircraft to lay them accurately from altitudes of up to 4,600 m. (15,000 ft.). The Soviet Union did not possess influence mines before 1943—which delayed its development of the means with which to sweep them—and Japan never had any of its own though it laid a few captured ones.

From September 1940 onwards the Luftwaffe dropped sea mines by parachute on to British cities with devastating effect. The 1,000 kg. (2,200 lb.) Luftmine, which the British called a land mine, was an ordinary B magnetic mine with a dual fuze; the 1,000 kg. Bombenmine was known to the British Bomb Disposal Service as the ‘G’ mine.

The Germans and the British had developed the magnetic mine, which was normally detonated on the sea-bed by the magnetic field of a ship's steel hull, during the First World War. The Germans kept working on its development between the wars but the British only continued to investigate possible counter-measures. The Germans therefore scored a tactical success when they started laying them in September 1939, causing heavy losses. However, for various reasons, their mine-laying operations were halted from early December 1939 until the end of March 1940, and when they were resumed not enough mines were laid to neutralize British shipping.

Churchill's attempts to retaliate against German mine-laying, with an operation (ROYAL MARINE) to float small air-dropped magnetic mines down the Rhine, was initially blocked by the French (see phoney war). When it was finally implemented, after the start of the German offensive in the west in May 1940 (see FALL GELB), it suspended nearly all river traffic between Karlsruhe and Mainz, but had no effect on the German campaign.

In November 1939 the British Minesweeping Service had found a German magnetic mine intact and by mid- 1940 had developed a magnetic sweep. Once this had been introduced, the Germans began to use acoustic mines which were detonated by the sound of a ship's propeller acting on a diaphragm within them. But they repeated their error of introducing them prematurely and by November 1940 the first British acoustic sweeps—which magnified sound—were operational.

Mines were swept by specially-built minesweepers, or by converted civilian craft such as trawlers and paddle steamers. The most common equipment for sweeping contact mines in the Allied navies was the Oropesa sweep, so-called after the first ship to use it in 1919. Towed behind the minesweeper this severed the mine's mooring cable with a specially-weighted wire equipped with sharp cutters and a small explosive charge. Once on the surface the mine was destroyed by gunfire. The principal method of destroying magnetic mines was the LL, or magnetic sweep. Two long, insulated, buoyant cables were towed astern of a wooden sweeper and an electric current was run through them to create a magnetic field which detonated the mines. Magnetic coils on wooden barges towed by a tug were also used, as were low-flying aircraft fitted with circular magnetic coils. Less successful were mine destructor ships with large electro-magnets in their bows. The most effective counter-measure was degaussing which obliterated the magnetic field of a steel hull.

Mine warfare at sea was a constant battle of wits between those laying the mines and those sweeping them. Both sides laid minefields of different types; manufactured mines that were both magnetic and acoustic; and introduced delaying devices which meant sweeping a minefield several times before the mines could be induced to detonate. In 1940 the Germans introduced sweep obstructors which were subsequently copied by the Allies. One was an explosive conical float, which severed the sweep wire before it reached the mine's mooring cable; another used static cutters to perform the same task. But perhaps the simplest and most effective was the introduction of heavy chain moorings which the sweep wires could not sever.

Refinements were continually being made, but the next operational use of a major advance in mine technology did not come until the Normandy landings in June 1944 (see OVERLORD) when the Germans introduced the pressure mine, codenamed OYSTER by the Allies. This device had been conceived by a German naval officer early in the war, but as the Germans could find no antidote they refrained from using it in case the British might find one, learn how it worked, and use it against them, especially in the Baltic's shallow waters. The British, who knew the principle on which it worked—a ship passing above altered the water pressure on the mine, which triggered the firing device—did not deploy it for the same reason.

The Germans were careful not to use the pressure mine operationally until they had plenty of them, and more than 400 were laid off Normandy. They caused considerable losses until one was found and dismantled. This enabled the British to compute the maximum speed at which a vessel could move in different depths without triggering the device, but no other antidote was ever found for it.

Some devices were called mines when they were not. ‘Mk24 mine’ was the cover name for a US-built acoustic torpedo (see guided weapons). The Long Aerial Mine, a British invention, was a bomb which was dangled in the flight path of German bombers by a wire suspended from a parachute. The Japanese invented a similar gadget. Neither was effective.

I. C. B. Dear

Bibliography

Achkasov, V., and and Pavlovich, H. , Soviet Naval Operations in the Great Patriotic War, 1941–45 (Annapolis, Md., 1981).
Elliott, P. , Allied Minesweeping in World War II (London, 1979).
Lott, A. , Dangerous Sea (New York, 1960).