1. SURFACE SHIP MINELAYING, 1939 to 1945

 

 

 

This Monograph outlines surface minelaying operations by Royal Navy warships during WW2. It was prepared for the Librarian of the Chatham Historic Dockyard Trust. Further details are available in the Naval Staff History (Mining) copies of which are held in the National Archives at Kew and in the Naval Historical Branch, HM Dockyard Portsmouth. Reference can also be made to the individual Chronologies of War Service for the warships listed in this Digest. These contain the identity and dates of the individual Operations concerned. 

 

Introduction

 

This digest of minelaying covers the activities of major war vessels, submarines and coastal forces craft and excludes the very extensive minelaying carried out by aircraft. Apart from the Naval Staff History "British Mining Operations 1939-45" which provides a comprehensive record of all these activities and some details in Roskill's "War at Sea”, very few details are available about this arduous and dangerous work.

 

British minelaying operations were carried out from the day that hostilities commenced until 10 May 1945 when the submarine RORQUAL laid 44 mines off Thousand Islands in the Pacific. They were carried out in all types of weather and ships deployed in coastal waters had the additional hazard of enemy mines apart from encounters with hostile warships and aircraft.

 

Three types of minelaying can easily be identified. Defensive minefields, as laid in the Dover Straits, along the East Coast of UK and in the North Atlantic, including the Denmark Strait. Anti-submarine traps as placed in both the NW and SW Approaches, the Irish Sea and English Channel.

 

The overall effect of the Defensive Barriers cannot be said to have been worth the very considerable expenditure of material and manpower. On the other hand, Offensive minelaying, particularly by aircraft was far more rewarding in terms of the ratio of mines laid to casualties inflicted. Minefields laid in shallow coastal waters, especially those with a high density of shipping, not only disrupted enemy shipping but also made necessary the deployment of significant numbers of mine countermeasures vessels.

 

At the beginning of the war a programme was in hand to convert a number of merchant ships for use in laying large numbers of mines to establish Defensive Barrier minefields. The only Offensive minelaying capability available was that provided by the cruiser ADVENTURE, the six "E" and "I" Class destroyers designed for this duty, six submarines with a minelaying capability and a Coastal Minelayers (PLOVER). Construction of new Fast Minelayers of the ABDIEL Class was not completed and the "T" Class submarines which were designed for minelaying had not yet joined the Fleet. (See Appendix I.)

 

The following Table shows the number of mines in the different types of minefield laid by surface warships.

 

 

Analysis of Mines Laid

 

Type of Minefield	No. of Mines	Effort (%)
Defensive	159,992	60
Deep Trap	26,546	10
Offensive by Major Vessels	11,223	2
Offensive by Coastal Forces and Submarine	10,443	7
Offensive by Aircraft	55,646	21
Total	263,850	100

 

 

Offensive Minefields - Proportion of Effort and Results

 

Type of Vessel	Mines Laid (%)	Casualties (%)
Fast Minelayers	54	19
Submarines	16	28
Coastal Forces Craft	30	53

 

 

Royal Navy minelaying amounted to 28% of total number of mines laid and 13% of total casualties. For mines laid by aircraft, the proportion was 72% for 87% of total casualties.

 

 

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2. ANNUAL SUMMARY OF OPERATIONS WORLDWIDE

 

 

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Home & NW European Waters

 

Plans to establish minefields in the Straits of Dover and in the Heligoland Bight had been prepared prior to the outbreak of hostilities. Conversion of mercantiles to supplement minelaying capabilities already available was in hand and deployments were made as a matter of urgency on 3rd September 1939. Apart from these two important requirements another small defensive minefield was laid in the entrance to the Firth of Forth and in late September a limited minelaying operation was undertaken in the North Sea off Flamborough Head followed by one in the Clyde estuary.

 

Dover Mine Barrage - Mining of the Straits of Dover in conjunction with the French Navy had been decided in January 1939 to prevent transit by submarines between the North Sea and Atlantic Ocean through the English Channel and to assist in control of shipping. Four minelayers were used for this task.

 

After the first Operation (GR) it was evident that ADVENTURE was difficult to manoeuvre within the confines of Dover harbour and she was withdrawn. The work was continued by the other three ships until November when SHEPPERTON was paid off to take up duty as a War Office Transport.

 

Heligoland Bight - Experience during WW1 had shown the advantage of offensive minelaying in the Heligoland Bight in order to restrict movements of coastal shipping and introduce a risk factor to naval operations in the area. At the same time due consideration of neutral shipping requirements was necessary. After two operations in September further minelaying in this area was abandoned because of lack of navigational aids and the presence of enemy minefields. In December after study of intelligence reports minelaying operations in this area were resumed.

 

East Coast - The provision of A/S minefields to protect shipping off the East Coast although attractive was not practicable because of lack of suitable ships, although their deterrent effect was recognised. When ADVENTURE became available she was deployed on this task. The minefield laid was far smaller than the declared area and 50 'dummy mines' were also laid. These were set to be visible at half tide so they would be easily seen by aircraft or shipping in order to create the impression of a far larger mined area.

 

ADVENTURE was mined off the Tongue Light Vessel when on passage south after this lay and sustained major damage. She was an early victim to a German magnetic mine with many casualties. Temporary repair at Chatham and refit at Plymouth kept her out of action till September 1940.

 

Thames Estuary - To counter extensive enemy minelaying which caused many shipping losses a series of deep small minefields were laid in positions likely to be crossed by minelaying U-Boats. The decision to establish a mine barrier along the length of the East coast was made in late December and work began off the Fame Islands on 30th in Operation LA.

 

Miscellaneous Minefields - Defensive minefields were laid by the coastal minelayers PLOVER, the first being an important addition to the existing protection at the entrance to the Firth of Forth. When the Home Fleet ceased to use Scapa Flow after the sinking of ROYAL OAK it was decided to provide a new deep minefield in the Clyde estuary. This proved unsatisfactory due to mooring problems and had to be swept clear on completion of lay. The Firth of Forth defences were again strengthened by an additional minefield in December. The Boon Defence Vessel BAYONET sank in this field on 22 December and some adjustment had to be made by sweeping.

 

Foreign Stations

 

Local minefields at Singapore and Hong Kong had been planned before outbreak of war. Four destroyers in the Local Flotilla were converted to their minelaying role and deployed to lay defensive fields at Singapore and Hong Kong immediately war on Germany was declared. The Hong Kong Ferry MAN YEUNG was requisitioned and also fitted for minelaying to assist in the provision of these defences.

 

 

 

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Home & NW European Waters

 

Most of the minelaying effort was deployed on defensive fields which assumed even greater importance after the German occupation of much of the European coastline as anti-invasion measures. The Dover Barrage was completed by February, after delays due to weather and shortage of minesweepers and the East Coast Barrier was reinforced and extended. Implementation of the revised plan for the Northern Barrage did not start until July when ships and adequate stocks of mines were available for this tremendous task. Offensive minelaying was restricted to Norwegian waters and near French ports due to the limited availability of ships.

 

Dover Barrage - The minefield west of Folkestone was completed but further work was delayed when HAMPTON refitted in February and the proposed minefield extending to Vame Ridge was cancelled after the German attack on France and the Low Countries. HAMPTON was transferred for War Office service in July but the availability of a French and a Dutch minelayer allowed the swept channel available for Belgian and Dutch shipping to be mined after the Dunkirk evacuation. Anti-invasion fields in Dover Straits were laid by destroyers as their higher speed and better AA armament made them more suitable. When work finished on the Dover Barrage 9897 mines had been laid.

 

Heligoland Bight - Only three more fields were completed in the Ems estuary due to weather and defects and in March the destroyers were redeployed on other duties. The occupation of western Europe made necessary the provision of defensive fields (CBX Series) to protect naval forces operating off the Dutch, Belgian and French coasts, and as an anti- invasion measure. Following reports of German surface ships being deployed in the North Sea in May, further minelaying was carried out by destroyers. The first of these operations was successful but the next carried out in August was a total disaster. The ships engaged ran into an enemy minefield and ESK and IVANHOE were sunk with EXPRESS sustaining major damage.

 

East Coast Barrier - The function of this Barrier changed after May 1940 when it became an anti-invasion measure instead of a safeguard to shipping and an independent minefield was laid in The Wash during July for this purpose. Special arrangements were made to inform ships using the East Coast route of changes to the boundaries of the danger area. A number of shallow fields were added until July when lack of escorts prevented further work for two months. More 'Dummy mines' were also laid to deter enemy minelaying incursions (See 1939 details). Deep A/S minefields were added in the Moray Firth and Thames Estuary. The Operations on the Barrier were in the "BS" Series except those carried out in the Northern Section by ships from the 1st Minelaying Squadron which had an "SN" Series identity. The loss of PRINCESS VICTORIA which detonated a magnetic mine off the Humber on 18 May reduced the available minelaying capability. A total of 17,789 mines were laid in 1940.

 

Northern Barrage - The creation of a mine barrage across the sea area between the Orkneys and tine Norwegian Coast had been investigated in July 1939, but could not be implemented until ships and mines were available. However after the occupation of Norway it was decided to position minefields between the Orkneys, Faeroes and Iceland to restrict enemy access to Atlantic shipping. Five merchant ships had already been requisitioned for conversion to minelayers.

 

Detailed planning of a series of Operations ("SN") and the establishment of support facilities had been delegated to a new Flag Officer (RA(ML)). Gaps were to be left in this minefield to allow passage for the fleet and for convoys. In addition to sections of the Barrier on either side of the Faeroes, mines were to be laid in the Denmark Strait, north of Iceland to narrow the navigable part of that passage to the Atlantic. Antenna mines (See Appendix 2) were to be used in the Northern Barrier as fewer would be needed to achieve the same effect.

 

The 1st Minelaying Squadron, based at Kyle of Lochalsh was formed on 1?th June but the requisitioned ships were not available for minelaying until October. Lack of escorts and support problems also restricted use of these ships during 1940 but five operations were carried out and 10,300 mines laid at the southern end of the Faeroes - Iceland section. In addition 541 mines were laid by TEVIOT BANK during September in the Fjords between the Faeroes Islands to restrict neutral shipping movements ("ZMD" Series). RA(ML) Operations in the "SN" Series were also used to identify minelaying in SW Approaches and in the Moray Firth. On 27 November the 1st Minelaying Squadron sustained a major loss when PORT NAPIER caught fire at Port ZA and sank after several explosions on board. Fortunately some of the mines were jettisoned and so a major disaster was avoided. This ship had proved to be an excellent minelayer.

 

Norwegian Coast - In March, before the German invasion of Norway, minelaying destroyers from D20 Flotilla and TEVIOT BANK were detached for duty with Home Fleet ships in March to carry out a minelaying operation (WILFRED), intended to deny use of coastal waters off Norway by German iron ore ships. Two minefields were to be laid with a 'simulated' minelaying operation to provide a diversion. The minelayers were on passage when the German invasion commenced and one operation, off Stadtlandet by TEVIOT BANK was immediately cancelled to release her escort for Fleet duty. The other lay off Vest Fjord and the diversion went ahead as planned. Although other minelaying was projected to close shipping channels off Norway only one was implemented ("2MA"), off Trondheim on 25 April.

 

Channel Coasts - A series of destroyer minelaying operations off the French coast commenced in November to threaten enemy coastal traffic and U-Boat movements. These deployments were also intended to increase the work-load on German minesweeping requirements.

 

Western Approaches - No minefields were laid in either NW or SW Approaches before 1940 because of lack of resources and the extensive use of these areas by merchant shipping. However after the German occupation of France merchant ships using St, George's Channel were diverted and had to enter the Irish Sea through North Channel.

 

As a result it was decided to lay mines in SW approaches as an anti-invasion measure and to deter U-Boat activity. This field was provided between Cornwall and the coast of Eire and suitable gaps were made to allow use by allied and neutral coastal shipping. Two operations were carried out by RA(ML) ships in July and early August with reinforcement at the end of the year bringing the total number of mines laid in SW Approaches to over 6,000.

 

The higher concentration of shipping in NW Approaches due to the diversion made necessary additional protection against U-Boats and a series of deep fields were laid by RA(ML) ships near Rathlin Island for this purpose. There were many delays in completion of these 'zig-zag' fields due to lack of escorts since the four "TOWN" Class (Ex USN Destroyers attached to ML1 were not ready for escort duty until November. After a series of premature explosions of MarkXX/XVn (Antenna) mines a special trial was carried out off Kyle of Lochalsh. The resultant field also provided additional protection for the Base. By the time the task was complete U-Boats had been driven farther west by the increasing use of aircraft patrols.,

 

Foreign Waters

 

No surface minelaying was carried out in either the Mediterranean or Far East.

 

 

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HMS Welshman, compare with photograph below (David Downey)

 

 

General - During this year minelaying activity increased and work was progressed both on the East Coast Barrier and the Northern Barrage. In addition fields were laid off the French coast, both as A/S measures and against movements of enemy warships and mercantile traffic. Significant changes were the commencement of minelaying by Coastal Forces craft and the availability of the first ABDIEL Class Fast Minelayer

 

Minelaying in the Mediterranean was restricted because of the extensive losses of warships during the evacuations from Greece and Crete. The fast minelayers in particular were required for other duties. Nevertheless some losses were inflicted on enemy shipping. Existing Defensive minefields at Singapore and Hong Kong were reinforced and a new Defensive field was laid of the east coast of Malaya. Additionally a minelaying operation was carried out to prevent use of anchorages in the Kerguelen Islands in the Indian Ocean.

 

Home & NW European Waters

 

More offensive minelaying was undertaken and the East Coast Barrier was reinforced to better suit anti-invasion requirements. Offensive fields were laid off the French Channel coast and another off Norway. Use of MTB's and ML's for limited offensive minelaying in shallow coastal waters increased very considerable by the end of 1942. It proved very successful and resulted in a significant decrease in enemy coastal traffic and losses of minesweepers.

 

East Coast - Changes were made to existing Gaps off Flamborough Head and Orfordness and radio beacons were used to assist in safe navigation. A 'Test lay' of a new A/S mine (MkXIX) was carried out in January. During February TEVIOT BANK was damaged by a near miss whilst on passage and was withdrawn for repair lasting 4 weeks. Improvements were made in AA protection and the availability suitable escorts. Work on the northern section by ships from ML1 continued (See 1940). TEVIOT BANK was transferred to RA(ML) command to reinforce the ships employed on the Northern Barrage in July and replaced by PLOVER.

 

Northern Barrage - The immense minelaying task begun in 1940 by ships of ML1 continued throughout the year with new fields laid north and south of the Faeroes as well as in the Denmark Strait. A new Deep A/S Field was also provided NW of the Butt of Lewis. Cover for operations in the "SN" Series was given by ships of the Home Fleet which also detached additional escorts to supplement the TOWN Class attached to ML1. In February the Title of RA(ML) was changed to RA(M) to avoid confusion with Coastal Forces Motor Launch Flotillas. The existing minefield in Denmark Strait was extended to provide an additional hazard should BISMARCK attempt a break-out north of Iceland. It facilitated the task of cruisers watching this passage and may have assisted in the detection by SUFFOLK in May.

 

A refitting programme in US ports was implemented during the year and ships were withdrawn in turn for this purpose. Work on the Northern Barrage was delayed by fog and gales which caused collisions. After MENESTHEUS was damaged a drifting Mark XX (Antenna) Mine special instructions were issued to immunize this type until a safety device had been fitted.

 

Intelligence reports in July that U-Boats were using the Faeroes - Iceland passage made necessary a policy change and a series of Deep A/S fields were laid NW of Sulisker. Torpedo damage to SOUTHERN PRINCE and machinery problems in ADVENTURE, together with the US refit programme reduced RA(M)'s capability but did not delay work on the Deep Fields.

 

Western Approaches - Reinforcement of the minefield in the SW Approaches (ZME) was completed by PLOVER after ADVENTURE was mined in Liverpool Bay when on passage to act as AA Guardship at Liverpool on 14 January. As PLOVER was under refit in a Humber shipyard there was a delay of a month before this work could be continued. Despite delays by weather the 16 remaining operations in the St. George's Channel field, carried out at night and unescorted, were completed on 21 April without any other problems. A variant of the smaller Mark XIX A/S mine was used for the first time and allowed more to be embarked compared with the Mark XV previously used. ADVENTURE was under repair until 1942.

 

Norwegian Coast - In early January an offensive minefield was laid NE of Egersund because of an increase in coastal traffic due to blockage of the railway between Oslo and Bergen. Another operation ("EA"), by destroyers, to lay mines off Fro Havet, near Trondheim was abandoned later that month during passage because of appalling weather conditions. Another Offensive minefield was laid close inshore near Stadtlandet by MANXMAN, escorted by KENYA and LIGHTNING.

 

Channel Coasts - Surface ship Offensive minelaying increased considerably during this year with the use of Coastal Forces craft and deployment of the remaining destroyers of the 20th Flotilla as well as ABDIEL Class fast minelayers. Seventeen minefields were laid to endanger coastal traffic, including blockade runners, between Brest and Seine Bay, off Brittany, and NE of Cap D'Antifer. Moored magnetic mines (M Mark 1) were used for the first time off Le Havre in February. After the SCHARNHORST and GNEISENAU arrived at Brest in March the newly commissioned ABDIEL laid additional fields on Little Sole Bank and west of Brest to threaten their possible transit via the English Channel. A total of 3,052 mines were laid by destroyers and fast minelayers which operated from south coast ports for these operations.

 

The three destroyers were withdrawn from minelaying service in April after which surface minelaying was carried out by fast minelayers and Coastal Forces craft with escorts from local Destroyer Flotillas. From September onwards MANXMAN and WELSHMAN were also deployed on the coastal route until December when MANXMAN was required to embark stores for Gibraltar and WELSHMAN alone laid three A/S fields off Lorient.

 

Foreign Waters

 

Mediterranean - Only limited minelaying took place because of the other more essential demands. A planned lay during May by the newly arrived ABDIEL in the Sicilian Channel proved impracticable but later that month she was deployed on what proved to be a most profitable operation. A minefield was laid to the west of the entrance to Corinth Canal on 21 May and claimed 2 escorts and 2 merchant ships in a military convoy later the same day.

 

MANXMAN was temporarily detached from RA(M) to lay a minefield off Leghorn on the west coast of Italy. This operation ("MINCEMEAT") gained much renown since it required the ship to adopt disguise when passing close to enemy occupied territory. A false bow and stern structure and other features were altered to provide a silhouette similar to that of a French LEOPARD Class cruiser. French colours and pennants were hoisted and members of the ships company wore simulated French uniform when near land. 140 mines were laid without any detection and the ship returned at 37 knots until clear of the Gulf of Genoa. 'Fancy Dress ' was assumed when passing Cape Corse and discarded when off the Spanish coast.

 

An unusual feature of mining activities in the Mediterranean during 1941 was the use of APHIS, a River Gunboat, to lay some aircraft mines (Type A Mk 1) off the North African coast at Bomba.

 

Far East - Reinforcement of minefields at Singapore and Hong Kong was undertaken early in the year. A British merchant ship (KUNG WO) was requisitioned at Singapore to assist in this work. Between February and July a Defensive minefield was laid off the east coast of Malaya. Before TEVIOT BANK arrived to supplement the minelaying capability available, three additional defensive minefields were laid in the approaches to Singapore by KUNG WO and STRONGHOLD. In order to prevent use by raiders the Australian cruiser AUSTRALIA laid 18 ground mines in anchorages at the Kerguelen islands.

 

When Japan launched her attacks on Hong the only mining possible was in the entrance to North Lantau Channel by THRACIAN on 10 December. At Singapore a minelaying plan agreed with the Netherlands Navy was implemented and an extensive A/S minefield also laid across the eastern entrance by TEVIOT BANK and KUNG WO.

 

 

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General - Minelaying activities were considerably enhanced by the availability of coastal forces craft and more aircraft sorties. No further work was carried out on the East coast Barrier after November and the value of the Northern Barrage was beginning to be questioned, without however any final decision being made about the future deployment of ML1 ships. Deployment of the Fast Minelayers for reinforcement of existing A/S fields in SW Approaches was frequently prevented by their use for the transport of supplies in the Mediterranean.

 

Two new types of mine were used in the Northern Barrage for the first time in 1942. One was a modified variant of the MkXX Antenna mine. This type (Mark XXU) had an additional floating lower antenna which would be more effective against U-Boats. The other was the M Mark 1 moored magnetic mine laid by ADVENTURE in May.

 

Several minefields were laid to cover the possible transit eastwards of SCHARNHORST, GNEISENAU and PRINCE EUGEN from Brest. No surface Offensive laying operations could be carried out off Norway and only one in the Mediterranean because of lack of ships. An A/S field was laid off Aden in December by TEVIOT BANK on detachment fron the Eastern Fleet. Minelaying in the East Indies was restricted because of the volatile situation on that area.

 

Home & NW European Waters

 

East Coast Barrier - Both the northern section and the longer stretch south from the Tay to Thames estuaries were reinforced. Ships of ML1 continued to be employed for the extension north of Rattray Head, with additional escorts provided from the Home Fleet. Reshaping of the northern gap was assisted by use of a radio beacon at Red Head north of Dundee. In the southern section PLOVER closed Gap "E" and reinforced existing fields.

 

Northern Barrage - Work on minefields in the Butt of Lewis was continued and two lines were laid across the Skuo and Dimon Fjords in the Faeroes before the planned strengthening of the Barrier was undertaken. Fran mid-February maximum effort was deployed to provide new fields south of Iceland before starting new deep fields on the Faeroes Bank. As soon as weather conditions were suitable, moored magnetic mines were laid in the Denmark Strait to replace earlier losses due to ice. Home Fleet cover was provided during operations off Iceland. Minelaying on the Faeroes Bank was interrupted to complete the Denmark Strait requirement and also to lay the last field off Butt of Lewis. Delays due to weather and other factors prevented completion of 1942 programme before ships of the squadron went for refit.

 

English Channel - A series of offensive fields using magnetic mines was laid off the Dutch coast to deter movement of coastal shipping and to extend enemy minesweeping capacity during January. Six operations by the Fast minelayers during February to counter transit of the German warships from Brest were unsuccessful largely due to efficient minesweeping. They were used when available to lay A/S minefields in the Bay of Biscay. The bulk of surface minelaying was done by coastal craft

 

Foreign Stations

 

Little surface minelaying was carried out in the Mediterranean and Far East. ABDIEL was detached from the Mediterranean in December to lay a series of Offensive minefields in the Indian Ocean. By the time she arrived the military situation had significantly changed and Defensive minefields were required in the Andaman Islands which were vulnerable to Japanese attack. ABDIEL carried out two minelays but then grounded at Port Anson and damaged a propeller shaft which could not be repaired on Station. She was not available for further service until November after repair in UK. The Andamans task was completed with a lay in South Prepais Channel by TEVIOT BANK during March. MANXMAN arrived as relief in April, but carried out no minelaying because of Japanese air superiority, and was deployed on a series of visits determine future mining policy in the theatre. She was redeployed in the Mediterranean but after one Offensive minelay in the Sicilian Narrows was damaged by a U-Boat torpedo and was under repair in UK till May 1945- Work on a deep A/S field at the southern entry to the Red Sea in December by TEVIOT BANK which was detached from the Mediterranean for this operation.

 

 

 

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General - The tempo of surface minelaying was considerably less during this year. Work on the East Coast Barrier and Northern Barrage was discontinued and mining in the Mediterranean was limited.

 

Home & NW European Waters

 

East Coast Barrier - In order to provide additional protection against E- Boat attacks on convoys off The Wash, three fields were laid in the Haddock Bank area using modified assemblies in MkXVII mines. During the lay of the first field several premature explosions occured and after trials (BS87), it was decided to stop production pending further investigation but continued to be used by ML's. No further mines were laid in the East Coast Barrier in which 38,045 mines had been used. Oily one enemy warship had been sunk and it had failed to meet its intended purpose to safeguard shipping. Tne diminishing threat of invasion made any reinforcement even less justifiable.

 

Northern Barrage - The future of this extensive set of minefields and of the ships of ML1 was considered by the Admiralty at meetings in January and July. The overall policy was revised since this field had proved very difficult to maintain as an effective barrier. Another factor was the large expenditure of steel required for a project which had already required over 80,000 mines. Apart from provision of an additional field at tine entrance to Denmark Strait, the only future minelays approved were a series of Deep A/S fields at the northern end of the Faeroes - Iceland gap. On completion of the programme the First Minelaying Squadron was disbanded and the Base at Kyle of Lochalsh was run down although retained as a mine embarkation port. In all a total of 92,083 mines had been laid (35% of all British minelaying effort but the passage of U-Boats was not being prevented.

 

Both the large Defensive minefields had failed to justify their existence and been more dangerous to our own forces than to the enemy.

 

Western Approaches, Norway and Channel Coasts - No surface minelaying was carried out in Western Approaches or off Norway but coastal forces craft and submarines were deployed for extensive offensive minelaying in coastal waters off France and the Low Countries.

 

Foreign Stations

 

Mediterranean - Other than the completion of the A/S field in the entrance to the Red Sea started in 1942 the only surface ship mining activity during 1943 comprised ten offensive fields in the Sicilian Channel against enemy convoys supporting military operations in North Africa. Special arrangements were needed to ensure that sufficient mines were available for these operations and ADVENTURE was used to carry mines from UK to a storage depot at Mers el Kebir. Both ABDIEL and WELSHMAN were lost although not actually engaged in minelaying at the time of their sinking.

 

 

 

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This period included very extensive and complicated minelaying operations in support of the Normandy landings (Operation NEPTUNE). These were carried out by surface craft, including many by Light Coastal Forces and aircraft. In addition a series of minelays by carrier borne aircraft were carried out off Norway. As military activity was on the Italian mainland the only minelaying in the Mediterranean was in defence of ships involved in landing operations.

 

Home & NW European Waters

 

General - Minelaying support for NEPTUNE was part of an overall plan called Operation MAPLE for which surface minelayers were used mainly in Phases II and m. Responsibility for implementation lay with the CinC's at Plymouth (HOSTILE Series), Portsmouth ("KN" Series), and Nore ("QU" Series) together with the Flag Officer at Dover ("NL" Series).

 

These operations were intended to provide protection for cross Channel convoys against attacks by E-Boats and R-Boats and amounted to 39% of the total number of mines laid. Surface ships, other than Coastal Craft laid 1,420 mines out of the total naval contribution of 2,891. The newly commissioned Fast Minelayer APOLLO carried out lays off Brittany to deter use of the western approaches to the Channel from the Bay of Biscay (1,170) and PLOVER was deployed to lay mines in the eastern approaches (250).

 

Anti-submarine Minefields - In August increased U-Boat activity had caused losses of shipping on passage to the beachheads and a series of deep A/S fields were laid by PLOVER under these routes (Operation PASTURE). When the Bay of Biscay submarine bases were occupied this series was discontinued. Considerable effort was also expended to provide additional deep A/S fields in the SW Approaches to the Irish Sea and later during November in the NW Approaches off Malin Head. During December, increased U-Boat activity was anticipated in inshore waters off the north Cornish coast and deep A/S fields were laid by PLOVER and APOLLO.

 

Norwegian Coast - minelaying intensified very considerably after the threat posed by major German warships was relieved. Seven Offensive mining operations were carried out in coastal waters by aircraft from Home Fleet aircraft carriers and three by a French submarine

 

Foreign Stations

 

Minelaying was very limited. A projected minelay by TEVIOT BANK off Anzio was cancelled after she had been diverted whilst on passage from the East Indies. She was later deployed to lay a defensive field off Capri.

 

 

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No surface minelaying by major warships was carried out except in Home Waters where deployments were concentrated on A/S fields.

 

Home & NW European Waters

 

General - The significant attention being paid by ‘Schnorkel’ fitted U-Boats in SW Approaches and in the English Channel made necessary the provision of additional protection around focal points used by shipping. A series of minelays was started in January by Coastal Forces craft and PLOVER (Operation BRAZIER) around the vicinity of buoys marking the entry to swept channels. On completion of this work further Deep fields were laid in Portsmouth Command (BUTTERMILK) and Plymouth Command (ARTIZAN) all intended to endanger U-Boat operations against Channel shipping. PLOVER and VAN DER ZANN were used for most of these '2 Line' fields with NIGHTINGALE and Coastal Craft for the rest.

 

Western Approaches - Work on anti-submarine traps around the north Cornish coast was completed and a new field was laid across St. Georges Channel. In NW Approaches an additional field was laid by APOLLO and three 'O' Class Destroyer minelayers when a projected lay off Russia was cancelled. The second lay in NW Approaches, started on 5th May, was completed on VE Day and was the last minelaying operation in European waters.

 

Irish Sea - The policy of concentrating minelaying effort on anti-submarine protection was extended into the Irish Sea when work in the SW entrance had been covered. Deep fields were laid by APOLLO off Anglesea, and the Isle of Man. Another off Strumbles Head was laid by ARIADNE.

 

Foreign Stations

 

All minelaying was carried out by submarines and aircraft on the Far East Station.

 

 

 

CONCLUSIONS

 

More effort was deployed on Offensive minelaying after 1942 because of the total failure of Defensive minelaying. With the possible exception of the Dover Barrage, Defensive minefields had proved to have little effect on enemy strategy or deployments and had resulted in allied casualties. Equally important this work had diverted badly needed ships from Fleet and convoy defence in order to provide escorts for the minelayers at a time of significant shortages.

 

The Northern Barrage in particular was described by CinC Home Fleet as "the least profitable voluntary major undertaking of the war". A/S minelaying in the Heligoland Bight, which the Germans recognised as an area vital to their naval activities, had been too infrequent and when carried out had been insufficient in quantity. Defensive minefields placed after 1940 can now be seen to have been an unnecessary drain on materials and manpower which involved considerable effort.

 

In order to be most effective, Deep Trap minefields needed to be placed in focal points where convoys with adequate A/S escorts were in transit. The St. George's Channel Field reinforced in 1942 - 43 had been placed in an area not being used for convoys and presented many dangers to our own forces.

 

Offensive minelaying, particularly that carried out by Coastal Forces ML's and MTB's as well as by aircraft had proved far more rewarding. Coastal Forces craft were easily converted for this duty and could lay accurately in restricted waters. In the Mediterranean, despite the limited choice of suitable areas, this type of mining was well rewarded, especially that carried out by submarines. Experience showed that submarines by their very nature could observe shipping movements with comparative safety and select suitable areas based on this knowledge. As shown in the following Table, aircraft minelaying was the most successful of all agents used. It is perhaps relevant to note that events since 1945 have shown that Offensive minelaying has been used in the Middle East and required deployment of considerable mine counter measures effort.

 

Minelaying by both the Fast Minelayers and Destroyers was generally unsuccessful and in the final analysis can be seen to have been of little value especially if used on Defensive minefields or to lay A/S Traps in unsuitable or unnecessary locations. Geographic factors play an important part in determining the outcome of a mining campaign, and when carried out in shallow coastal waters with a high density of traffic, enable achievement of a high ratio of mines laid to shipping casualties. Another important aspect is that any sustained minelaying in such areas, apart from its disruptive effects on shipping will place a continual drain on mine countermeasures operations with high risk of casualties being incurred

 

In 1939 although the only types of British mine available for immediate use were of the moored contact type, research and development had been carried out into the future use of influence mines. These could be detonated by changes in the local magnetic field due to passage of a ship (or submarine). Influence mines detonated by acoustic signals had not been developed by the RN at the outbreak of war. Surface minelaying therefore used the existing stock of moored contact mine (Mark XVH) mines. In order to reduce the number needed to cover any given area a new variant (Mk XX) was introduced in 1941 for use in the Northern Barrage. It embodied a floating antenna contact with which would cause detonation instead of with the Hertz Horn fitted on the mine casing of earlier types. The Mark XX was not satisfactory and was replaced in late 1941 by a new more reliable type (Mark XXII) which had an upper and lower antenna to increased its lethal range.

 

The moored magnetic mine (M Mark 1), in production by September 1939, was first laid in February 1941. A magnetic ground mine (A Mark 1), developed as an air drop weapon, became available early in 1940 and a variant suitable for minelaying by ML's and MTB's was first used in September 1941. Moored acoustic mines were developed after the outbreak of war and laid by ML's in October 1942. Combinations of magnetic and acoustic influence ground mines were in general use by 1945 and greatly added to the problems faced by enemy defence forces. The addition of time delay mechanisms, mixing of moored and ground mines in the same field and use of obstructors to compound minesweeping difficulties all served to further stretch German mine countermeasures resources. It must however be acknowledged.that the enemy invariably found a solution to these complications before the situation became irrecoverable.

 

Apart from the casualties due to mining the operations shown in the Table, considerable disruption was caused to enemy seaborne traffic. British mining imposed a severe load on repair facilities and a continual need to deploy resources on extensive mine countermeasures.

 

British losses included one fast minelayer (WELSHMAN), and two minelaying Destroyers (ESK and IVANHOE) apart from coastal craft and submarines, with extensive damage to ABDIEL, MANXMAN, ADVENTURE and EXPRESS. Total naval personnel casualties were 461 killed and 49 wounded with 108 prisoners of war.

 

History alone can judge whether this very hazardous and complex series of operations was completely justifiable.

 

Table of Results of Surface Ship Minelaying Operations 

 

Type	Location	Mines laid	Casualties	Remarks
Defensive	East Coast UK	38,045	1	Torpedo Boat T6.
Defensive	Northern Barrage	92,083	1	Probable only (U-Boat)
Deep Trap	Western Approaches	30,154	2	U-Boats
Offensive	Home Waters	8,898	15	Including coastal waters.
Offensive	Norway	841	4	Ratio 1:210
Offensive	Heligoland Bight	2,240	4	Plus two destroyers by misfortune
Offensive	Mediterranean	2,038	28	Ratio 1:72
Offensive	Far East	18	Nil	-

 

In contrast:

 Coastal Forces laid 6,642 mines and claimed 134 casualties (Ratio: 1:48)

 Aircraft laid 55,646 mines and claimed 1,666 casualties (Ratio: 1:33)

 

Sources:

British Minelaying Operations (Naval Staff History (BR1736 (56) (1) and (2) )

War at Sea 1939 - 45 by Stephen Roskill

HMS ELECTRA by T. J Cain, by HMS INTREPID by Mack.

The Torpedomen by E. N. Poland.

 

 

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3. SURFACE SHIPS USED FOR MINELAYING 1939 TO 1945

 

(for more ship information, go to Naval History Homepage and type name in Site Search)

Click here for Service histories of the Destroyers listed.

 

 

HMS Welshman (Bob Hanley)

 

 

Ship	Type	Displacement (Tons)	Speed (Knots)	Mines Carried	Remarks
Purpose Built Warships
ADVENTURE	Cruiser	6,740	28	280	Completed 1936
ABDIEL	Cruiser	2,850	40	160	Commissioned 3/41. Lost 9/43 (not laying)
LATONA	Cruiser	2,650	40	160	Commissioned 4/41 Lost 10/41 (not laying)
MANXMAN	Cruiser	2,650	40	160	Commissioned 6/41
WELSHMAN	Cruiser	2,650	40	160	Commissioned 9/41. Lost 3/43
ARIADNE	Cruiser	2,650	40	160	Commissioned 3/43
APOLLO	Cruiser	2,650	40	160	Commissioned 3/44
ESK	Destroyer	1,375	36	60	Completed 1935. Lost 8/40
EXPRESS	Destroyer	1,375	36	60	Completed 1935. Lost 8/40
ICARUS	Destroyer	1,375	36	60	Completed 1937
IMPULSIVE	Destroyer	1,370	36	60	Completed 1937
INTREPID	Destroyer	1,375	36	60	Completed 1937
IVANHOE	Destroyer	1,375	36	60	Completed 1937
OBEDIENT	Destroyer	1,540	37	60	Completed 1943
OPPORTUNE	Destroyer	1,540	37	60	Completed 1943
ORWELL	Destroyer	1,540	37	60	Completed 1942
SCOUT	Destroyer	905	31	40	Completed 1919
STRONGHOLD	Destroyer	905	31	40	Completed 1919. Lost 3/42 (not laying)
TENEDOS	Destroyer	905	31	40	Completed 1919. Lost 4/42 (not laying)
THANET	Destroyer	905	31	40	Completed 1919. Lost 4/42 (not laying)
THRACIAN	Destroyer	905	31	40	Completed 1920. Lost 12/41 (not laying)
PLOVER	Coastal Mlyr	805	14.75	100	Completed 1938
NIGHTINGALE	Tender	298	10	16	Completed 1932
Auxiliary Minelayers (Requisitioned from Trade)
AGAMEMNON	mv	7.593	16	542	Completed 1929. Blue Funnel
HAMPTON	ss	2,839	16.5	270	Completed 1934. Channel Ferry
KING WO	ss	4,.636	10	248	Requisitioned 1/41
MENESTHEUS	mv	7,494	16	438	Completed 1929. Blue Funnel
MAN YEUNG	ss	371		100	Requisitioned 8/39
PRINCESS VICTORIA	ss	3,167	16	244	As HAMPTON
PORT NAPIER	ss	9,.600	16	574	Completed 1940
PORT QUEBEC	ss	5,936	14.5	550	Completed 1940
SHEPPERTON	ss	2,839	16.5	270	As HAMPTON
SOUTHERN PRINCE	mv	10,917	17	556	Completed 1929. Prince Line
TEVIOT BANK	ss	5.087	12	280	Completed 1938. Bank Line
Foreign Minelayers
WILLEM VAN DER ZAAN	Coastal Mlyr	1.300	15.5	100	Dutch
POLLUX	Coastal Mlyr	2,461	14	236	French. Only in 1939.

 

 

 

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4. CHRONOLOGICAL SEQUENCE OF SUBMARINE MINELAYING OPERATIONS 1939-45

 

(for more ship information, go to Naval History Homepage and type name in Site Search)

Click here for Service histories of some of the Submarines listed.

 

 

HMS Seal (NP) 

 

 

Operation	Date		Submarine	Mines Laid	Geographic Area
1 9 4 0
FD 1	4 Apl 1940		NARWHAL	50 MkXVI	Heligoland Bight.
FD 5	13 Apl 1940		NARWHAL	50 MkXVI	Laeso Channel, Norway.
FD 6	1 May 1940		NARWHAL	50 MkXVI	Hirsholm, Norway.
FD 7	4 May 1940		SEAL +	50 MkXVI	Vinga, Kattegat, Norway.
			+ SEAL subsequently captured.
FD 14	10 May 1940		RUBIS (FS)	32 SH4 (French)	Egersund, Norway.
FD 12	11 May 1940		NARWHAL	50 MkXVI	North of Bud, Norway.
FD 11	15 May 1940		PORPOISE	48 Mk XVI	Hovden Island, Norway.
FD 15	27 May 1940		RUBIS (FS)	32 SH4 (French)	North of Haugesund, Norway.
FD 16	3 Jun 1940		NARWHAL	50 MkXVI	Jaerens Rev, Norway.
FD 17	9 Jun 1940		RUBIS (FS)	32 SH4 (French)	North of Bergen, Norway.
FD 19	12 Jun 1940		NARWHAL	50 MkXVI	North of Haugesund, Norway.
None	13 Jun 1940		GRAMPUS +	50 MkXVI	Off Augusta, Sicily
			+ GRAMPUS subsequently lost on 16 June.
FD 18	14 Jun 1940		PORPOISE	50 MkXVI	Ramsey Fjord, Trondheim.
None	14 Jun 1940		RORQUAL	50 MkXVI	Off Brindisi, Italy.
FD 20	26 Jun 1940		RUBIS (FS)	32 SH4 (French)	Yetr Fjord, Trondheim.
FD 21	4 Jul 1940		NARWHAL	50 MkXVI	Grip Holen, Trondheim.
FD 22	Jul 1940		NARWHAL +	50 MkXVI 4-4-	Griptarene, Trondheim
			+ NARWHAL was presumed lost on 31 July
None	21 Jul 1940		RORQUAL	50 MkXVI	Off Tolmieta, Cyrenaica.
FD 23	29 Jul 1940		PORPOISE	50 MkXVI	Heligoland Bight.
None	17 Aug 1940		RORQUAL	50 MkXVI	Off Taukra, Cyrenaica.
FD 24	19 Aug 1940		CACHALOT	50 MkXVI	West of Gironde
FD 26	13 Sep 1940		PORPOISE	48 MkXVI	North of La Rochelle
FD 27	23 Sep 1940		CACHALOT	50 MkXVI	Point Penmarch area.
None	4 Oct 1940		RORQUAL	50 MkXVI	Off Taukra, Cyrenaica.
None	5 Nov 1940		RORQUAL	50 MkXVI	Off Misurata, Tripolitania.
None	9 Nov 1940		RORQUAL	50 MkXVI	Off Misurata, Tripolitania.
1 9 4 1
FD 28	26 Jan 1941		CACHALOT	50 MkXVI	Off Bud, Norway.
None	28 Jan 1941		RORQUAL	50 MkXVI	Two fields in Adriatic -Sansegolsland, and off Ancona.
FD 30	15 Feb 1941		CACHALOT	50 MkXVI	Vest Fjord, Narvik area.
None	25 Mar 1941		RORQUAL	10 MkXVI	Palermo Approaches.
None	26 Mar 1941		RORQUAL	40 MkXVI	Trapani Approaches.
FD 32	28 Mar 1941		CACHALOT	50 MkXVI	Gironde area.
None	11 May 1941		RORQUAL	50 MkXVI	Off Salonika, Greece.
FD 33	21 Aug 1941		RUBIS (FS)	18 Vickers TIII 4 ***	Egersund., Norway.
			*** 14 mines not laid due to battery damage after attack on two merchant ships.
None	26 Aug 1941		RORQUAL	50 MkXVI	Off Zante Island, Corinth.
None	8 Oct 1941		RORQUAL	50 MkXVI	Gulf of Athens.
None	21 Oct 1941		RORQUAL	10 MkXVI	Off Cavioli Is. , Sardinia
None	22 Oct 1941		RORQUAL	40 MkXVI	Off Cape Ferrate, Sardinia.
FD 34	19 Nov 1941		RORQUAL	50 MkXVI	Off La Rochelle.
1 9 4 2
None	11 Jan 1942		PORPOISE	46 MkXVI	Suda Bay, Crete.
FD 36	16 Jan 1942		RUBIS (FS)	32 Vickers TIII	Off St. Jean de Luz.
FD 37	21 Mar 1942		RUBIS (FS)	32 Vickers TIII	Heligoland Bight.
FD 38	12 Apl 1942		RUBIS (FS)	32 Vickers TIII	Grip Holen, Norway.
FD39	5 Jun 1942		RUBIS (FS)	32 Vickers TIII	Bayonne - Bordeaux area.
FD 40	7 Jul 1942		RUBIS (FS)	31 Vickers TIII	Bayone-Bordeaux area.
None	12 Aug 1942		PORPOISE	46 MkVI	Ras-el-Tin, Cyrenaica
FD41	14 Aug 1942		RUBIS (FS)	32 Vickers TIII ***	Arachon Point
			*** 30 mines not laid because of defect in mine rails
None	30 Aug 1942		RORQUAL	15 MkVI	SE of Corfu
FD42	19 Sept 1942		RUBIS (FS)	32 Vickers TIII	Malangan Fjord, Tromso
None	3 Oct 1942		PORPOISE	46 MkXVI	West of Tobruk
None	8 Dec 1942		RORQUAL	36 MkVI ***	Cani Rocks, off Bizerta
			*** 3 mines not laid and discarded later in deep water
None	13 Dec 1942		RORQUAL	11 Mk XVI	Off Ischia, Naples
1 9 4 3
None	18 January 1943		RORQUAL	48 Mk XVI ***	Cani Rocks off Bizerta
			*** Mine doors jammed initially – 2 mines not laid.
None	24 Feb 1942		RORQUAL	50 MKXVI	SE Marettimo Is, Sicily
None	22 Mar 1942		RORQUAL	50 MKXVI	Off Tranpani, Sicily
None	22 April 1942		RORQUAL	50 MKXVI	Off Favignana, Sicily
None	30 April 1943		RORQUAL	50 MkXVI	Off Marettimo, Sicily
None	15 May 1943		RORQUAL	50 MkVI	Off Punta Stilo
None	2 July 1943		RORQUAL	29 MkXVI	Gulf of Kassandra, Greece
	3 July 1943		RORQUAL	21 Mk XVI	Skiathos Channel Greece
FD43	5 July1943		RUBIS (FS)	32 MkXVI	Arachon Point
FD44	5 Aug 1943		RUBIS (FS)	32 MkXVI	Brest
None	5 Aug 1943		RORQUAL	29 MkXVI	Gulf of Salonika, Greece
None	6 Aug 1943		RORQUAL	21 MkXVI	Lemnos, N Aegean Sea
FD45	30 Aug 1943		RUBIS (FS)	32 MkXVI	Bayonne area
None	9 Sept 1943		RORQUAL	15 MkXVI	Trikirich. N Aegean
None	10 Sept 1943		RORQUAL	15 MkXVI	Skiathos Channel, Greece
None	11 Sept 1943		RORQUAL	20 MkXVI	Lemnos,N Aegean Sea
FD46	2 Oct 1943		RUBIS (FS)	32 MkXVI	Pointe de Penmarch area
1 9 4 4
FD47	24 Feb 1944		RUBIS (FS)	32 Vickers TIII	Arachon Point area
ML02	14 Mar 1944		TRESPASSER	12 M MkII	Mati Bank Malacca Str,
ML01	19 Mar 1944		TAURUS	12 M MK II	Arca Is. Malacca Str.
FD48	25 Mar 1944		RUBIS (FS)	31 Vickers TIII	West of La Rodhelle
ML03	18 Apl 1944		TAURUS	12 M Mk II	South of Penang
MLO4	13 May 1944		SURF	8 M MK II	Off Pulo Terutan, Malaya
ML05	14 May 1944		TALLY HO	12 M MK II	Buja Shoal Malacca Str
ML06	16 May 1944		TACTICIAN	12 M Mk II	Langkawi Snd, Malaya
ML07	18 May 1944		SEA ROVER	8 M Mk II	Sembilan Is. Malacca Str
ML09	2 June 1944		TANTALUS	12 M Mk II	Dindings, Malaya
ML10	3 June 1944		STOIC	8 M Mk II	North of Penang, Malaya
ML08	4 June1944		TEMPLAR	12 M Mk II	Dindings, Malaya
ML011	7 June 1944		TANTIVY	12 M Mk II	Sembilang Is., Malacca Str.
ML012	14 June 1944		SURF	8 M Mk II	Off Pulo Terutan, Malaya
ML013	24 June1944		TRUCULENT	12 M MkII	Klang Strait, Malay
ML014	6 July 1944		PORPOISE	30 Mk XVI	Off Deli River, Sumatra
None	8 July 1944		PORPOISE	10 M Mk II	Malacca Straits
				16 MkXVI	Off Deli River, Sunatra
ML015	16 Sept 1944		TRENCHANT	12 M MkII	Sembilang Ch. Sumatra
ML016	24 Sept 1944		TUDOR	10 M Mk II	Off Pulo Lantar, Malaya
FD 49	24 Sep 1944		RUBIS (FS)	31 Vickers TIII	Jaerens Rev, Norway.
FD50	8 Oct 1944		RUBIS (FS)	31Vickers TIII	North of Bergen, Norway.
ML017	30 Oct 1944		TRADEWIND	12 M MkII	Off Mergui, Siam.
ML018	19 Nov 1944		THOROUGH	12 M MkII	Outer Mati Bank, Sumatra
FD 51	24 Nov 1944		RUBIS (FS)	32 Vickers TIII	Off Egersund, Norway
ML019	9 Dec 1944		PORPOISE	50MKXVI	Off Penang.
ML020	16 Dec 194		THULE	12 M MkII	Off Terutan, Malaya.
FD 52	4 to 19 Dec 1944		RUBIS (FS)	30 Vickers TIII	Jaerens Rev, Norway.
ML021	23 Dec 1944		THOROUGH	12M MkII	Off Terutan, Malay
1 9 4 5
ML022	3 Jan 1945		RORQUAL	50 MkXVI	Off Pukhet Is. Malaya
None	3 Jan 1945		O19 (Neth)	40 Vickers TIII	Off Bataviua
ML023	4 Jan 1945		RORQUAL	12 M Mk1I	Off Pukhet Is. Malaya
ML024	+ Jan 1945		PORPOISE	12 M MkII	Off Penang
ML025	+ Jan 1945		PORPOISE +	49 M MkII	Off Penang
			+ Lay completed before loss of PORPOISE
ML026	22 Jan 1945		RORQUAL	50M MkII	Ritchies Archipelago
ML027	23 Jan 1945		RORQUAL	12M Mk II	Andaman Is.
None	10 May 1945		RORQUAL	12 M MK II)	Sea of 1,000 Islands.
				50 M MkII	Off Java

  

Statistics and Notes:

 

The ratio of mines laid to casualties for all submarine minelaying was 1:49

The figure for the coast of Norway alone was 1:29.

Submarine minelaying accounted for 28% of all casualties due to naval minelaying.

Submarines laid 3,429 mines which was 16% of all mines laid by naval forces.

Casualties due to submarine minelaying:

 62 Vessels sunk totalling 71,797 GRT

 8 Vessels damaged totalling 20,904 GRT.