Minesweeping, Mines, and Malta: Contact

In January of 1940 Churchill stated: 

The magnetic mine, and all the other mines with which the narrow waters, the approaches to this Island [Britain], are strewn, do not present us with any problem which we deem insoluble. It must be remembered that in the last war we suffered very grievous losses from mines, and that at the climax more than six hundred British vessels were engaged solely upon the task of mine-sweeping. We must remember that

The sea was not any safer than land during the war. Mines: large metal spheres packed with explosives, rested beneath the waves. They could be air-dropped using parachutes, launched from ships, or smaller and faster mine-laying boats. As early as 1940, Italian torpedo boats and destroyers laid mines off Malta. By the war’s end, the axis laid thousands of mines around Malta, with one source putting the total at over 50,000. This rendered the passage in and out of the island a near suicidal affair were it not for minesweepers.

Italian torpedo boat ALTAIR, one of the first to lay mines off Malta in 1940. © Archivio Aldo Cherini

Minesweepers were used wherever the Royal Navy was. The first boats to spearhead Operation Neptune, the landings in Normandy (D-day) were British and American minesweepers. Clearing no less than 10 channels through which landing craft could push through, they led the way for the allies into Europe. In Malta, using Bangor, Halcyon, Hunt, and Algerine class minesweepers, paddle tugs, floats, the American BYMS-class and a whole host of converted ships, between 1940 and 1946, the 3rd, 12th, and 14th/17th, Minesweeping flotillas and auxiliaries swept thousands of mines. Some, such as HMS Speedy and HMS Eddy were almost lost or sunk after hitting a mine themselves during operations. 

The Germans would use a series of mines each fit for a specific purpose. They were designated as follows:

BM – Airborne mines laid without parachutes

EM – Moored Contact mines.  Mostly Hertz Horns.

FM – Shallow water contact mines, mostly moored types.

KM – Anti-invasion coastal mines

LM – Airborne parachute mines

MT – Ground mine torpedoes laid from torpedo tubes

OM – Surface mines

RM – Shore-controlled or independent ground mines

SM – Moored magnetic mines laid from mine tubes on U-Boats

TM – Magnetic (influence) mines laid from torpedo tubes

UM – ASW contact mines

The more simple versions were the EM series (A-U) contact mines. Using chemical or ‘Hertz’ horns, a passing ship would hit and break them off triggering an explosive chemical reaction (completing a circuit using an electrolyte/acid). These mines could also be used with switch horns that would trigger the booster charge on contact with a ship’s hull. This would detonate the main charge, usually made out of gun-cotton explosive, but cast TNT was also used at sea. These mines could be found anywhere underneath the waves and almost always tethered to an anchor on the bottom.

Dragging a buoy off the side of a ship, a cable with special cutters would slash through the sea cutting off the mooring lines of enemy mines, hence, ‘sweep’ them. The cable would keep its ‘J’ shape and structure using kites and otters, much like those used on deep sea trawlers to center their fishing nets. Minesweepers could also work in several stepped formations to clear and mark larger areas/corridors as safe with ‘dan’ buoys more efficiently. They could even sweep using a single cable tied to two or more ships at once. However, to counter this ‘aropesa’ method outrightly, the upper portions of German mines were later moored with increasingly longer metal chains instead of rope. Spearheaded by HMS Vernon: the Royal navy stone frigate tasked with torpedo and mine-warfare training and research, British minesweepers constantly adapted to such developments.

In 1942, the 14/17th minesweeping flotilla arrived in Malta as part of Operation Harpoon. Until then, Ploughboy, HMS Fermoy and HMS Abingdon worked relentlessly to keep the approaches to Malta and its harbours clear of mines. During the worst of the siege, enemy mine laying operations were so threatening that even drifters and small motor launches (ML) were converted into minesweepers. Gordon W. Stead commanded ML126 when it was instructed to equip and train itself for minesweeping operations in May of 1942. Up until then, they were tasked with coastal patrols, rendezvous and escorting submarines to harbour, and other pertinent duties. On one occasion they were ordered to tow in a damaged Italian e-boat outside the grand-harbour, promptly sunk by the Germans just after.  

The nimble motor launches were taught adequate for the job given they displaced roughly the same amount of water as the enemy mine-laying e-boats. At first they had some trouble figuring out how to use their outdated equipment dating back to the first world war. During their first sea-trial, the manoeuvring kite flew out of the sea. However, they soon adjusted to their unexpectedly assigned role. They would sweep behind one another, side by side, covering ground ahead of HMS Beryl, Malta’s last converted trawler at the time. She was sunk during the illustrious attack and refloated later the same year. 

This equipment that had lain in stores unused since World War I was now being expended at a prodigious rate, and I was asked to salvage what I could. Damaged items were repaired and new gear manufactured. Throughout this hectic period I had the most superb support from the crippled dockyard. (Stead, p. 80)

Paravane in use on HMS Bentinck, WW2. IWM A 19606

Stead recounts how some enemy mines were fitted with cutters for the minesweepers’ cables. This was unprecedented and caused constant repairs and replacements. Nevertheless, the ML carried on, even after being strafed by enemy fighters, painting mines on their funnel every time they cut one off a mooring. Despite being self-trained minesweepers, they were relatively highly successful. When a specially trained commanding officer later replaced Stead at the helm of the motor launches’ minesweeping operations, he asked where he was educted in minesweeping, receiving the prompt reply: “Right out there in the bloody minefield, sir” (Stead, p. 95).  

With other ML and trawlers, motor-launch 126 cleared the way for vital convoys to reach Malta and Submarines to return to island for offensive operations. However, the sheer amount of minefields and the coordination needed to traverse the cleared paths meant that things didn’t always work so smoothly:

About midnight the calm was shattered by the cry from aft, “BATTLESHIP approaching, sir!” This brought us up all standing. The only battleships for hundreds of miles could only be Italian. I put my glasses on it. It was the anti-aircraft cruiser HMS Cairo, leading the convoy towards the centre of the secretly promulgated swept channel, which was in fact now full of mines. No minesweepers were in sight. There was nothing I could do nor advice that I could give, so I watched in helpless awe as the ships plodded by, the cruiser followed by two deeply laden merchant ships with destroyers and MLs arrayed on either beam. Miraculously, they passed in measured sequence until, inevitably, there was a shower of sparks on the far side of the convoy as a “Hunt” class destroyer, the Polish-manned Kujawiak, hit a mine. (Stead, p. 87)


Cowie, J. S. (1949). Mines, Minelayers and Minelaying. London: Oxford University Press.

Melvin, Michael J. (1992). Minesweeper, The Role of the Motor Minesweepers in World War II. Worcester, UK: Square One Publishing.

Stead, Gordon W. (1988).  Leaf upon the Sea : A Small Ship in the Mediterranean, 1941-1943, UBC Press.

(Additional sources hyperlinked where relevant in text)


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