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
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
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
Offensive by Major Vessels
Offensive by Coastal Forces and Submarine
Offensive by Aircraft
Offensive Minefields - Proportion of Effort
Type of Vessel
Mines Laid (%)
Coastal Forces Craft
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.
2. ANNUAL SUMMARY OF OPERATIONS
1 9 3 9
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
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
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
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.
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
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
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.
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.
1 9 4 0
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.
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
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 FaeroesIslands 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.
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
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
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
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 RathlinIsland 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.,
No surface minelaying was carried out in either the Mediterranean or Far
1 9 4 1
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
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
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
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 LiverpoolBay 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.
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
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 SeineBay, 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
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.
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 CorinthCanal on 21
May and claimed 2 escorts and 2 merchant ships in a military convoy later the
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 CapeCorse 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
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
18 ground mines in anchorages at the Kerguelen islands.
launched her attacks on Hong the only mining possible was in the entrance to
North Lantau Channel by THRACIAN on 10 December. At
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.
1 9 4 2
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
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
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.
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 SicilianNarrows 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
1 9 4 3
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
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 -
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
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.
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
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.
1 9 4
This period included very extensive and complicated minelaying
operations in support of the Normandy
(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
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.
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
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.
1 9 4 5
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 '0'
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.
All minelaying was carried out by submarines and aircraft on the
Far East Station.
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
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
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,
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
East Coast UK
Torpedo Boat T6.
Probable only (U-Boat)
Including coastal waters.
Plus two destroyers by misfortune
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)
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