September – December 1939 (2_14)
Sea mines and weather modification
mines, bombs planted at different levels under the sea surface, are an
excellent means for a magnificent experiment to study weather
modification. As oceans are huge, one certainly needs more than a few
mines for proper effect. But if the experiment is more confined, let us
say to the North Sea and Baltic Sea, any result may become visible and
be felt quickly. Something of this nature happened in late 1939. Within
a period of just four months after parties to the war had planted
thousands and thousands of mines in the North Sea between Scotland,
Dover and Skagerrak and in the Baltic Sea, Northern Europe experienced
an extremely cold winter. This is not the only surprise. In the
Netherlands and North Germany, immediately adjacent to the German Bight
and Southern Baltic Sea, where the bulk of the mines had been laid in
autumn 1939, the winter was the coldest in more than 100 years. About
100 to 300 years ago, Europe and the northern hemisphere had been
in the icy grip of the so-called ‘Little Ice Age’. Suddenly the
period before 1850 returned.
sea mines as a weapon
WWII Allies and Axis countries laid about 600,000 sea mines in European
and Atlantic waters. While comparing mining activities during the period
of four autumn months of 1939 and those 65 months that followed from
1940 to 1945, one may tend to think that this short period of four
months is hardly significant and can be summarily ignored. That would
be wrong for the following reasons:
During the first four months of war the ‘monthly-average’ of
mines laid was possibly 10 times higher than during the next five years
and could have been in the range of between 50,000 to 100,000 or more,
due to the fact, that
the countries could immediately use their accumulated stockpile,
sea mines were regarded as ‘cheap’ weapons and it was not
difficult to produce them in large numbers,
neutral countries also could and did use mines as a ‘defensive
At the time WWII started in September 1939, the oceans and seas
were in their “natural status”. But the exploding of sea mines and
other military activities as the war progressed through days, weeks and
months, interfered with the ‘common processes’. And within a month
of the start of the war, sea areas in question lost their ‘common
seasonal average’, as it had existed before.
reasons stated above, while discussing the issue of sea mines, only the
period from September to December 1939 will be covered here. However,
heavy impact of the war machinery on European waters will be dealt with
in two further chapters elsewhere. (A)
details: (A) Sea war events 1939, 2_13; and Depth charging 1939, 2_15.
the North Sea
- December 1939)
mined their East coast from Dover to the Orkneys successfully during the
first few months of war. In September 1939 alone, the British minelayers
Adventure and Plover planted 3,000 mines across Dover
Street (English Channel). In the second half of September the barrage
was completed by 3,636 U-boat mines, consequent to which Germany lost
three U-boats in October.
The British set up the East Coast Barrier, a mine barrage between twenty
and fifty miles wide from Scotland to the Thames, leaving a narrow space
between the barrage and the coast for navigation. In late 1939 the
British Admiralty intended laying a 500-mile minefield of unprecedented
size, a barrage in a strip of thirty to forty miles. That was a
“gigantic effort to check the German submarine campaign”. (NYT, 31
though it is difficult to verify the number of mines laid by the British
in the North Sea immediately after commencement of the war, the total
number of mines laid during autumn 1939 would certainly have crossed
10,000. Presumably the number was much higher, if one can rely on a
report by the NYT in early January 1940. : “British naval vessels are
sowing some of the last mines needed to complete Great Britain’s
30,000,000-pounds protective shield for east-coast shipping. The
minefield extending from Kinnairds Head, Scotland, almost to the mouth
of the Thames, is the most extensive field ever laid.” (NYT, 11
January 1940). If one assumes that the weight of those mines varied
between 300 and 1,200 pounds, the number of mines laid in autumn along
the east coast alone, would be between 25,000 and 100,000 mines.
Bight (Deutsche Bucht)
Navy engaged in planting contact mines probably much more actively from
Holland’s coastal waters (off Terschelling) northwards across the
Helgoland Bight up to the entrance of the Skagerrak, at a distance
between 50 and 100 km off the coast of Schleswig-Holstein and Denmark,
called “Westwall”. The most north-westerly point announced by the
Germans as ‘Dangerous zone’ was the position: 56° 30’ North and 4°
25’ East. That was about half the distance between Skagerrak and
Scotland. The first minefield locations were off Terschelling, Esbjerg,
near Helgoland and two places off Jutland. (NYT, 5 September 1939).
Specific warnings had been given to more than 100 Danish fishing cutters
from Esbjerg. (NYT, ditto). It was reported that one unidentified cutter
had been blown up seventy miles west of Wyl light ship. (NYT, ditto).
For about three weeks a flotilla of at least 25 naval vessels was
engaged in laying mines along the “Westwall”.
was difficult to verify how many mines the flotilla had planted within
the first few weeks, as it was not possible to get reliable figures
about the stockpile the Germans had on September 1st. The
number of mines laid during the period in question could be as few as
20,000 or as many as 200,000. But as the distance from Terschelling to
56° 30’ North is about 350 kilometres (170 sea miles) and as the
deployed 25 naval vessels were able to put in place several thousand
mines per day it seems reasonable to assume that, by the end of
September at least the first 10,000 mines and by the end of October
20,000 were in place and the “Westwall” was more or less completed
in the following months. According to a report by the NYT – Magazine,
as many as 300 mines an hour could be laid by one minelayer. (NYT, 18
February 1940). From the total of more than 200,000 sea mines the German
Navy used in WWII, presumably one-third of the total would have been
laid in the North Sea during the early days of the war.
a number of missions Home Fleet’s surface vessels laid mines close to
the Axis shipping lanes and channels, e.g. the British destroyers Esk
and Express laid mines at assumed ‘exit channels’ close to
the “Westwall” as early as mid September,
while the British East Coast was frequently supplemented with contact
mines laid by surface vessels and magnetic mines laid either by German
naval vessels, U-boats or air planes.
along the West coast of Britain, 1939
Home Fleet organised the laying of a number of mine fields on the
Atlantic coast of Great Britain and the English Channel, e.g. in the
Northern Channel (north entrance of the Irish Sea), at the entrance to
Liverpool, Cardiff, Plymouth, Southampton and the Eastern part of the
English Channel (Isle of Wight, Le Havre, Dover). (NYT, 17 December
1939, section 4).
the Baltic Sea, 1939
had just started when 1,555-ton Greek ship Kosti hit a German
mine two miles south of Falsterbo/Sweden on 4th September and
a “terrific explosion was reported in the minefield south of the Great
Belt, west of the Danish island of Zealand”. (NYT, 5 September 1939).
The Danish Government announced plans to plant mines in its waters. (NYT,
ditto). Actually, the Germans laid about 1,000 mines on September 4th
at the entrance to the Danish waters, the ‘Belts’. Mine laying
continued. The situation worsened day-by-day for six long years.
How many mines the Germans planted in the Southern Baltic is difficult
to verify. In the Western Baltic it would have been many thousands
before the winter of 1939/40 arrived and as a result the German Baltic
waters fell prey to a compact ice cover.
riparian countries planted mines as well. Even the hard pressed Poles
with the help of minesweepers Czajka, Jasolka and Rybitwa managed
to drop 60 mines south of Hela (Gdanska Bight) on September 12th.
The Soviet Navy started laying mines in the Gulf of Finland in late
September, which also saw a number of mining activities by Germans,
Finns and Russians during November and December 1939.
details: A fairly detailed account of what had happened in the Gulf of
Finland when the Soviet Union invaded Finland in December 1939 is given
in the paper: Russian-Finnish war, 2_41.
standard mine in WWI and at the start of WWII was the moored contact
mine, a buoyant material filled with explosives of up to 1,000 kg. To
nullify their effect special ships used distant means to cut the mooring
chain or wire attached to the mines to float them. Sometimes they
exploded before reaching the surface but if it surfaced it was blown up
by rifle shots.
used magnetic mines for the first time in November 1939. The NYT soon
reported that: “Some wild stories have appeared here suggesting
that the Germans have invented a so-called ‘magnetic mine”. (NYT, 22
November 1939). Actually, one magnetic mine was discovered on the shore
near Southend on November 22nd and was examined by the
Navy’s mining school.
Only two countermeasures were available against magnetic mines. One was
to explode the mine by towing a cable, which passed an electric current
through the water. From the point of view of climate, this was the worst
possible result. The mine exploded at its location, at a depth of 20,
50, 100 metres or more, producing the highest possible “stirring”
effect in the water column above. The other countermeasure was to
deactivate the ship’s ‘magnetism’ so that it could pass near the
mine without activating it. This may have saved the ships in a few cases,
but the mine remained a threat until it exploded later or until it was
same was the case with Oyster mines, which were equipped with pressure
mechanisms and were first used by Germans off Normandy and Cherbourg in
1944. Sweeping them in WWII meant exploding them by countermining.
Limiting the ship’s cruising speed to less than four knots gave them
Navy mostly used antenna mines, mines that can be planted at any depth
and from which long thin copper cables supported by small metal buoys
reach up to within a few feet of the surface. These exploded when a
submarine (or metallic body) touched the antenna, thus making it
unnecessary for the submarine to strike the mine itself. (NYT, 31
while exploding mix a column of water within seconds. Sweeping for mines
proved to be a tremendous round the clock operation travelling millions
and millions of miles in the sea for detecting and destroying the
‘weapon in waiting’. The efforts made during WWII had been
tremendous. German Defence machinery against Allied mining involved
46,000 personnel, 1,276 sweepers, 1,700 boats, and 400 planes, whereas
the British Defence against Axis mining involved 53,000 men and 698
When on November 19th , 1939 five ships were destroyed by
mines the urgent need for a huge mine sweeping operation became obvious.
(NYT, 20 November 1939). The discovery of a ‘sample mine’ on
November 22nd confirmed the effectiveness of countermeasures
significantly. The British Admiralty quickly put a pre-war plan into
action, whereby 800 commercial trawlers, drifters and whalers were
requisitioned, fitted out with wire sweeping gear and their crews
did the Mine Warfare do to the Weather?
this point one can skip explaining the principal threat: ‘stirring’
the sea by exploding mines as well as effects of either throwing or
eliminating mines by surface vessels. Such events coupled with the
sinking of vessels with resultant pollution caused by cargo of the
doomed ships, would have changed the ‘common status’ of the sea, and
thus the general ‘blueprint’ for the weather. The pre-winter months
are particularly sensitive in storing summer heat or losing it
prematurely by storm, wind or war activities. The mechanism of heat
storage and release seems obvious. The question is how many mine related
events have occurred during the pre-winter months, i.e., September to
December 1939 that affected the composition of the weather?
number of ships, sunk by mines until the end of 1939, was significantly
large, but the exploding mines involved in the sinking of about 200
ships alone would hardly have raised great concern. The number of mines
exploded due to mine sweeping operations (see previous paragraph) is
actually much higher. It is a fact that mines often tend not only to be
“weapons in waiting” but also a “weapon that dies lonely”,
either by mere erosion or explosion due to other reasons than war. In
both cases, actual numbers are not available. If mines exploded
prematurely during laying procedure, the information rarely left the
inner circles of the Navy concerned. If mines exploded due to stormy
seas, bombing or drifting ‘the matter’ will go totally unnoticed or
go on record only in a few cases. A few examples of such cases are
US Mormachawk sailed with pilot assistance through a German
minefield in early September 1939 when five loose mines blew up 500
to 800 yards away. (NYT, 20 September 1939).
were unexplained explosions around the East Coast of England, which
were later discovered to have been magnetic mines going off
prematurely. Casualties became so serious that at one stage Thames
at Southend was closed for 36 hours, and Humber for two days.
“Gales have loosened several hundred mines in the German mine
field… drifting mines exploded on the coast near the suburbs (of
Copenhagen)…. So many mines are floating around that it is impossible
to destroy all of them due to bad weather.” (NYT, 6 November 1939).
will be never known as to how many mines exploded during storms, bombing,
shelling or drifting cargo or wrecks in large mine fields like the
German North Sea “Westwall”, and along England’s East Coast
barrage with possibly several ten thousand mines. However, it will be
significantly higher than any data on ship-sinking and mine sweeping
the end of the war when great efforts had to be made to clear the sea of
mines, it was observed that about 85% of the mines laid had
“disappeared” due to various causes and only a small fraction could
be found and eliminated, either by explosion below surface or at sea
following List of Events, even though in no way comprehensive, gives a
brief account of how mine warfare was resorted to in the North and
Baltic Sea in late 1939. A full picture would possibly require the
reproduction of thousands of reports relating to stirring, shaking and
mixing of Northern European waters.
Mining Events during late 1939
purpose of the following list of events is to give a brief illustration
of what happened in the first few months of WW II, how they contributed
to changes in weather conditions of the North and Baltic Sea so much
that an extremely cold winter could grip Europe and provide Central
Northern Europe with the coldest winter in 110 years. It is a fact that
the use of a huge number of sea mines from the first day of war together
with other naval and military activities such as patrolling, shelling,
anti-aircraft fire, bombing, depth-charging, and such other measures
that turned the sea ‘upside-down’, has significantly contributed to
the break-in of arctic conditions.
September 1939: North Sea (Helgoland Bight); The German navy commences
laying contact mines from the Dutch island Terschelling 150 sm (ca 277
kilometres) north with 5 cruisers, 16 destroyers, 10 torpedo boats and 3
The mining field is
called the “Westwall” as an imaginary extension of the
“Westwall” stretching from Basel/Switzerland along the river Rhine
to the northern border of Holland with Germany. The first mining
activities lasted until 20 September. Other mining missions were
undertaken at the same time (e.g. laying of the ‘Martha mine barrage’,
as part of the North Sea ‘Westwall’). Exact figures of the
number of mines laid in the first three weeks or in subsequent missions
are not easy to establish. According to Elliot, the Germans were
thought to have started the war with a stock of 200,000 moored mines.
This figure seems a little bit too high. As the previously mentioned
flotilla was able to manage the laying of up to 3,000 mines per working
day, it seems possible to lay of 20,000 to 50,000 mines within a period
of three weeks’.
September 1939: “Danish Government has decided to place mines at the
entrance to Mongedybet, Hollaenderdyet and Drogden. The purpose is said
to be facilitating control of these waters”. (NYT, 5 September 1939).
September 1939: Four U-boats drop magnetic mines in the estuaries of
Orfordness, Flamborough, Hartlepool and the Downs drowning four vessels
with a total of 16,000-tons and damaging one ship of 11,000-tons.
September 1939:The British destroyers Esk and Express laid
an offensive mine barrage on assumed German shipping channels along the
September 1939: Baltic Sea; Several naval vessels prepared minefields,
with at least 1,000 mines in the Western Baltic to control the Danish
waterways to Kattegat and Skagerrak, in which the Greek ship Kosti hit
a mine and sank on 4 September.
September 1939:The Dutch Navyloses the minelayer Willem van
den Zaan (1,270-tons) and the minesweeper Willem van
Ewijk (460 tons) to its own mines.
September 1939: “The German Government has broadcast a warning to all
ships to stay out of three dangerous zones near the entrance to the
Baltic. …The announcer said that the second and third zones must not
be entered at all and the first only behind a pilot ship. Presumably
these zones have been mined.” (NYT, 11 Sept.39).
September 1939: Baltic Sea; Polish minesweeper Czajka, Jasolka
and Rybitwa throw 60 mines south of Hela, near Gdansk.
September 1939: British minelayers Adventure, Plover and
support vessels laid 3,000 mines across the Strait of Dover.
September 1939: Soviet Navy plants mines in Gulf of Finland to protect
Kronstadt and Leningrad. (NYT, 22 Sept. 1939).
September – 23 October 1939: U-boat sea mines barrage with 3,636 mines
is laid across the Strait of Dover (between Folkestone and Cap Gris Nez).
After three U-boats were lost in October 1939, no further attempts were
made by U-boats to reach the English Channel through the Strait of Dover.
1939; North Atlantic: Britain places 2,600 mines between Orkney, Faroe
Presumably, the actual number (for 1939) could have been much higher, as
Britain laid 110,000 Mk XX mines between Orkney and Iceland between
October 1939 „A report from Falsterbo, Sweden, today said that a
German pilot boat was blown up south of Oresund when it struck its own
mine.“ (NYT, 17 October 1939).
October 1939: Mine operation off Humber by German torpedo boats and
destroyers sank seven vessels.
October 1939: On 21st October and 25th November
own mines sank German Coast Guard ships south of the Great Belt. (NYT,
26 November 1939).
November 1939: Off Copenhagen shore: “Gales have loosened several
hundred mines in the German mine field… drifting mines exploded on the
coast near the suburbs (of Copenhagen), breaking windows and frightening
citizens with their terrific detonations. Naval crews have destroyed no
fewer than forty-three mines from Koege Bay up to Amager Island, where
100,000 Copenhagen residents live in a district comparable to Brooklyn.
Along the whole southern coast mine alarms often make it necessary to
evacuate villages while experts empty or explode the mines. So many
mines are floating around that it is impossible to destroy all of them
in the bad weather.” (NYT, 6 November 1939).
November 1939: North Sea; in two different missions a total of seven
German destroyers undertook mining operations off the central Thames
delta, resulting in the sinking of two destroyers, one trawler and about
20 cargo vessels, respectively ca. 60,000 tons.
November 1939: North Sea, Humber Estuary, the mines of three destroyers
sink seven ships with a tonnage of about 40,000.
November 1939: Magnetic mines are flown and dropped by German Navy
planes on British shores for the first time.
November 1939: Danes mine sea way; (NYT, 21 November 1939).
November 1939: Thirty-nine drifting mines seen near England (NYT, 23
November 1939: Mines sink 22 ships in six days. (NYT, 23 November 1939).
December 1939: England claimed to have mined an area of 300 square miles
midway between the Schelde and Thames estuary. The freighter Sheaf
Crest of 2,730 tons struck a mine and sank at a south coast town. (NYT,
1 December 1939).
1939: British East coast, numerous mining operations by U-boats sinking
ca. 7 vessels.
December 1939: “A British tanker was sunk by mines off the southeast
coast of England…. She (San Calisto, 8,010-tons) struck two
mines, which went off with such a force that the blast shook buildings
on shore”. (NYT, 3 December 1939).
December 1939: “More than thirty mines were washed ashore on the
Netherlands coast today, but were exploded by military patrols without
damage”. (NYT, 4 December 1939). ”Mines and wreckages washed ashore
on the Netherlands coast on weekend. Westerly storms were silent witness
to the naval war raging outside the three-mile limit. Many mines
exploded on shore, but strict precautions taken by the Netherlands
authorities prevented casualties”. (NYT, 5 December 1939).
December 1939: “A third German mine patrol ship was blown up this
afternoon north of the mine fields off Denmark. German ship sank in less
than two minutes, her entire bottom blown up”. (NYT, 5 December 1939).
December 1939: German cruiser Nürnberg lays mines off
December 1939: Sweden mined her waters opposite of Aland Islands. (NYT,
6 December 1939).
December 1939: Two destroyers drop mines off Comer, sinking two ships,
December 1939: German naval motor gliders drop 27 mines in the Humber
and Thames estuaries.
December 1939: Russians claim that they have cleared the Finnish port
Petsamo (Barents Sea) of Finnish mines. (Hamburger
Anzeiger, 11 December 1939).
December 1939: Two days of German mining missions off Newcastle by five
destroyers resulted in the sinking of 11 vessels with a total tonnage of
ca. 19,000 tons.
December 1939: “Seven crew members of the Swedish battleship Manligheten
were killed today in an explosion while investigating a floating object
in the vicinity of Goeteborg….A small boat was sent to retrieve the
object. Suddenly there was a terrific explosion.” (NYT, 14 December
December 1939: Four British destroyers laid 240 mines in the river Ems
December 1939: The small village of Huisduinen near Helder was severely
affected by a drifting mine, presumably of Netherlands, which exploded
on being washed ashore at 7 o’clock this morning”. (NYT, 31 December
a small record of mine operation events during a short time period of
the initial four months of war, viz. September – December 1939, would
give a strong indication of the enormous forces that began to interfere
with the marine environment. This happened thousands of times each day.
The sea was ‘turned upside-down’ at innumerable locations. In
September 1939, military activities either increased evaporation, or
forced warm surface water into depths. Later in autumn the war machinery
reversed the process, forcing cooled surface water down and warmer water
up. (A) However, due to their shallowness the Northern European seas
have only a limited heat storage capacity. Once the heat is taken out, a
maritime winter climate is lost as well. This happened in the first war
winter of 1939/40. Consequently, since the first week of January 1940,
Northern Europe had gone back into the ‘Little Ice Age’. (B)
details: (A) Cooling the North Sea; (B) Northern Europe plunged into
arctic conditions, 2_11.