A German engineering training manual contains the following account of
the preparation of obstacles, minefields and demolitions under winter conditions.
The depths of snow in which mines become unreliable is of particular interest in
view of the number of unverified reports that mines will detonate when deeply
buried. The load distribution (i.e., the spreading out of the load over a greater
area as the depth below the surface increases) through snow from wheeled and in
particular, semi-tracked vehicles is, no doubt, appreciable. There must,
therefore be a limiting depth at which a given mine may be set and still function under
the desired surface load.
Thus far, there has been no evidence of electrified fences on the Russian
front, but there have been unconfirmed reports of their use in western Europe.
The possibility of erecting obstacles is greatly affected by winter conditions.
Deep snow forms in itself a natural obstacle; it hinders troop movements on roads
and across country. Under conditions of deep snow, movement is in general
limited to roads and paths which have been previously tracked, or from which the
snow has been removed. For this reason particular significance is attached to
obstacles on roads. Tank movements are delayed by deep snow. According to
present experience, tanks can force a passage through snow up to a depth of two
feet; but snow considerably reduces their capacity for climbing.
b. Natural Obstacles
Natural obstacles in winter are considerably more effective than under
normal conditions. Frozen rivers can be transformed into obstacles by demolition
of the ice-covering.* As obstacles they will remain effective for a length of time
depending on the rate of flow and on the temperature, also on the possibility of
keeping them open in the face of enemy action. Slowly moving rivers and lakes
cannot be kept open. The method of demolishing the ice-cover is to blow holes
in it; through these holes the main demolition charges are placed under the ice
by means of poles. The effectiveness of steep banks and excavations as good
antitank obstacles is increased by deep snow.
c. Artificial Obstacles
The following are artificial obstacles: wire fences, wire snares, trip wires
and barbed wire rolls.
(1) Wire Obstacles
(a) Erection in frozen ground. In frozen ground iron pickets, which can
be hammered in, are more practicable than wooden pickets. Sockets for pickets
can be prepared by engineers using power drilling equipment and demolition charges.
(b) Erection of wire obstacles in anticipation of deep snow. If deep snow
conditions are to be expected, specially long pickets must be used in erecting
wire obstacles. Wire can easily be set at the necessary height in woods and forests
by attaching it to trees. If time is lacking, or there is uncertainty as to whether
snowfall will occur, the upper strands of wire can if conditions permit be added
later. A specially raised wire fence is illustrated in figure 1.
(c) Erection of wire obstacles on frozen snow. On a frozen snow surface
pickets can be erected with the aid of heavy nails and cross-timbers, as shown in
figure 2. Another method of erecting an obstacle on snow is shown in figure 3.
Obstacles erected on snow have the disadvantage that under certain conditions
they may easily sink.
(d) Simple warning devices, in the form of empty tin cans containing small
stones or nails should be attached to all wire obstacles.
(e) Wire obstacles must be provided, on the side facing the enemy, with
chevaux-de-trise, or rolls of plain or barbed wire.
(f) Construction of electrified wire obstacles on ice. Electrified wire
obstacles can only be erected on ice by specially trained personnel. Simple wire
fence, rolls of plain or barbed wire and multiple-fence obstacles in the form of
several single fences. can all be constructed. Owing to the non-conducting properties
of ice, a length of wire netting, eight feet in width, must be laid as a ground one
foot in front of the electrified obstacle, and must be well connected to the ice by
iron pickets every 30 feet. If possible, the ground should be carried right through
to the river bed. Its effect can be increased by heavy snowfall. The obstacle is
assembled as shown in figure 4, and erected on the ice.
(2) Antitank Obstacles
(a) Snow as an obstacle. A continuous snow cover more than 2 feet deep
forms a good obstacle against attack by tanks. The exact depth of snow which
forms a complete obstacle to attack by tanks is not yet known, and snow should
never be completely relied upon as an antitank obstacle.
(b) Construction of snow walls. An effective antitank obstacle is provided
by two snow walls built one behind the other, as shown in figure 5. The snow
should be lightly tamped down.
(c) Artificial formation of ice. Roads can be made difficult of passage for
enemy vehicles, armored cars, etc., by artificial icing. This is specially effective
on steep gradients and slopes. Construction of snow walls in combination with
the stretch that has been iced increases the effectiveness of the antitank obstacle.
Ice-concrete obstacles, can be made -- see Tactical and Technical Trends No. 22
The laying of minefields depends on snow conditions. Under a snow layer
of one foot or more, Tellermines are no longer certain of detonation. S-mines
(jumping mines) which have already been laid remain effective through frost and
thaw, but are not certain of functioning under a depth of snow of four inches or
more. Increasing depth of snow diminishes the capacity for detonation, and at a
depth of 10 inches detonation will no longer take place. Mines of any type which
have been frozen in should not be lifted, but must be demolished....
d. Handling of Demolition Stores
German explosives are unaffected by cold, and retain their properties
through all conditions of weather and storage. In general the following precautions
should be observed:
(1) Demolition stores should be kept dry in shelters, separated from each
other on wooden supports, and protected from extreme variations in temperature.
(2) Safety fuze, 1930 pattern (Zeitzündschmur 30) must be protected
against cold. Safety fuze which has been frozen should be gradually warmed before
use, otherwise it is liable to break.
(3) Demolition stores must be examined at frequent intervals; if in bulk,
they should not be opened, but the condition of the outer layers only should be
*See Tactical and Technical Trends, No. 21, page 8.