1. TELLER MINES¹

a. Description

(1) The German Teller mine is constructed as follows (fig. 1):

(2) The igniter (fig. 2) is composed of:

The igniter operates when any pressure is put on it, as follows: the igniter presses on the washers in the hole, B, and the assembly, C', is pushed up. When sufficient pressure is exerted, the shearing pin, G', breaks, and the spring, D2, forces the striker down onto the detonator, thereby exploding the mine.

b. Neutralization

A German document captured in the Middle East, gives instructions for the neutralization of Teller mines. These instructions include turning the screwhead on the igniter to Sicher (safe) as well as pushing the safety pin F' home. Several Teller mines are now being examined by U.S. Engineers, however, and in a preliminary report they recommend that no attempt be made to turn the screwhead in either direction.

The igniter can, however, be locked by pushing home the safety pin, F', which will prevent the striker, D' from falling.

If the regular locking pin has been removed, an ordinary nail may be used as a substitute and inserted in the hole E'.

It should be remembered, however, that any mine may be made into a booby trap and in such a case normal methods of neutralization may serve only to detonate the mine.

The additional igniters which may have been inserted in the holes F and G may be neutralized in the same manner as the main igniter.

The mine should be carefully inspected, however, before attempting to neutralize any of the igniters, to see whether one or more of them is worked by a trip cord.

After the pin has been inserted in the hole, the whole igniter may be unscrewed and removed. This should be done only at some distance from the mine field so that in case of accidental explosion, the other mines will not detonate sympathetically.

Previous reports from the Middle East have stated that in a number of cases it has been found impossible to reinsert the safety pin. In this connection it has been suggested that the purpose of the molded rubber ring which lies between the main detonator-locking washer and the central sliding body in the igniter is to raise the latter slightly on removal of the safety pin so that the pin cannot be reinserted. However, tests on specimens which have recently arrived in Great Britain do not show any difficulty in replacing the pin. It appears, moreover, from the construction of the igniter, that when the safety pin is in position, the top of the striker is in contact with the small grub screw in the center of the igniter head, and cannot be further raised on withdrawal of the safety pin. The difficulty in replacing the safety pin, therefore, is probably due to distribution of the igniter head or to partial shearing of the pin, G'.

c. Use of Pressure Bar (fig. 3)

The above-mentioned German document describes this device as follows:

(1) "For hasty construction of road barriers, a pressure bar, 1.5 m. (4.92 feet) in length, resting on two Teller mines, is employed. The bar is fixed to the mines by two half-collars which are screwed together.

(2) "The barrier is to be anchored with ropes or chains to objects on either side of the road.

(3) "These barriers are most useful when a detour is not possible; for example, in roads running beside a river or canal, or in a cutting.

(4) "The number of mines recommended is two to six according to the length of the barrier desired, there being a pressure bar between each pair of mines."

(5) Comment.—(a) A provisional drawing of the pressure bar, based on the above description and on a photograph received from the Russian front, is given in figure 3. Dimensions, apart from the length, have been estimated from the photograph and are only approximate.

(b) The bar's "theoretical beam section," for maximum rigidity, implies a complicated method of construction, and the whole device seems an unnecessary addition to engineer stores.

(c) The purpose of the staples along the sides of the pressure bar is not clear. They may be intended for spiking the bar in position.

d. Laying of Mines

The following instructions for laying Teller mines (fig. 4)

are given in a translation of a German document just received:

(1) "Observe the correct depth and form of the trench.

(2) "The covering layer should not be of greater thickness than 20 to 40 mm. (3/4 to 1 1/2 inches).

(3) "Mines should not be laid in holes, as there is a definite chance that they may not detonate.²

(4) "An obvious mound over the site of a mine should be avoided.

(5) "When laid in roads, the surface should be repaired where possible with tar or cement.

(6) "It is important to lay Teller mines from 80 to 100 mm. (3 to 4 inches) below the surface; that is to say, the lid must not be less than 90 mm. (3 1/2 inches) below the surface; otherwise sympathetic detonation may occur when one mine is exploded. Mines should not be lower than 100 mm. (4 inches) below the surface; otherwise they may not function properly."

(7) Comment.—The figures given for depth of protective covering agree with a recent report received from Middle East, describing enemy mine fields at Tobruk. This report stated that the average depth of soil over the top of the igniter was 1 inch, and that the maximum depth was 2 inches. The figure of 100 mm. (4 inches) for maximum depth of a mine laid below the surface, taken in combination with an average of 30 mm. (1.2 inches) of loose covering above the igniter (height of igniter approximately 30 mm. (1.2 inches)), suggests that the site of the mine may be marked by a slight depression in the ground.

e. Use of Additional Igniters

No reports of additional igniters have been received, and officers of the British Middle East Force have always stated that Teller mines encountered are of normal type. It would be possible to use the normal igniter as a pull igniter by removing or shearing the shear wire and attaching a cord to the safety pin.

f. Sympathetic Detonation

Instances have been reported from Cyrenaica of Teller mines being spaced at 9-foot intervals. At this spacing, sympathetic detonation invariably occurs, and in one case the mines in a row 980 yards long went off simultaneously. Detonation at 15-foot intervals is uncertain, but British officers in the Middle East recommend special precautions when clearing mine fields at spacings closer than 20 feet.

g. Destruction

During the clearance of a Teller mine field at Tobruk it was found that the mines were over-sensitive, probably having been subjected to blast. It was therefore decided to destroy the mines in position. The field consisted of two rows at 15-foot spacing. One row was drawn towards the other by lengths of signal cable until the spacing was reduced to 7 feet 6 inches; and when one mine was fired, the whole field exploded.

h. Improvised Mines

German instructions for making improvised mines are as follows:

(1) "The improvised mines are to be made from prepared charges and standard igniters, and may be enclosed, partly or wholly, in wooden boxes.

(2) "High-explosive shells from which the fuze has been removed may be fitted with push igniters and used as antitank mines.

(3) "Hand grenades may also be used. Push igniters can be fitted to stick-grenade heads, either singly or in clusters of seven tied together with wire. In the latter case the center head should carry the igniter.

(4) "Improvised mines should be laid by observing the same general principles as for Teller mines. In booby traps (i.e., simple traps for the unwary to walk on) push igniters should generally be employed. Only in special cases will pull igniters be employed."

i. Layout of Mine Fields

German diagrams for the layout of antitank mine fields are given in figure 5.

The following instructions accompanied the diagrams:

(1) "Distance between the mines from center to center shall be 4 m. (5 paces) when laid on the ground, and 8 m. (10 paces) when laid on the surface.

(2) "The density of the mine field is 24 mines per rectangle of 32 by 12 m. (40 by 15 paces). One rectangle is laid by a squad of 12 men, and each squad is responsible for laying 3 rectangles.

(3) "A company consists of three squads, and lays nine rectangles. In laying mines in open spacing, there shall be four rectangles per mine field, and a distance of 40 paces between mine fields, measured as shown in the diagram. This distance applies also to mines laid in close spacing.

(4) "Mine fields are mapped on a scale of 1/2,500, and the complete scheme transferred to a 1/10,000 map. Mine fields are to be marked by poles, sticks, branches, or wire."

j. Antitank Mines

(1) In German and United Nations' experience with mobile desert warfare, it has been found essential for engineering and workshop units to carry a number of mines for emergencies.

(2) One report stated "200 mines at call are worth more than 1,000 available at 12 hours' notice."

k. Made-up Firing Devices

The German series of explosive blocks, detonators, igniters, and booby traps are screwed to match, whereas the British types of explosives and initiators are designed for sleeve fitting because of the greater variety of explosives in use.

2. MINE DEFENSES AT AGEDABIA

The following description of German defenses encountered at Agedabia³ has been received from the Middle East:

a. General Defense

The position was designed for all-around defense, with a perimeter at 3 to 5 miles from the center of the village. Wiring was scanty. On Italian sectors it consisted of a cattle fence, with three strands of wire on wooden pickets, whereas German sectors consisted of a box fence. Mines were laid about 20 yards inside the perimeter wire. At the date of the report, the depth and extent of these mine fields had not been determined.

b. Fire positions

Fire positions consisted of simple rifle pits, with gun pits at varying distances. These defenses bore every sign of improvisation, and were evidently incomplete. They appeared to have been only partially occupied. No overhead cover was observed. All tracks radiating from Agedabia were mined as shown in figure 6.

c. Mines

Teller mines were used exclusively on the tracks, holes having apparently been made with earth augers. In some cases two mines were placed one above the other 1 to 2 feet apart, the two being connected by a pull igniter. In Agedabia itself, open spaces and courtyards were freely mined, without any regular pattern, the mines being in some cases covered with cement.

(1) Traps.—Booby traps were set in many of the houses. These mostly consisted of a Teller mine, connected with a pull igniter either directly to a door or to a trip wire across the door. In some cases, hand grenades were fixed inside the door, in such a position that the man who set the trap must have gone out through a window.

(2) Wells.—No wells or cisterns were destroyed, but the principal ones were prepared with charges to be fired by booby traps. The main cistern contained a 40-pound charge and a Teller mine, connected with a pull igniter and cord to the manhole cover.

(3) Road.—The main road south of Agedabia had been heavily mined, mines being laid in real and artificial pot holes. In some cases a number of holes had been made, only a few of which contained mines. In sections where mines had been laid in the roadway, some were always laid indiscriminately in the shoulder of the road. A proportion of these mines contained bottom or side igniters. It was observed that the road was mined at each kilometer stone for the first 10 km. (6.25 miles) south of Agedabia. At approximately 24 km. (15 miles) south of Agedabia, two ditches (width, 8 feet; depth, 4 to 5 feet) had been cut across the 25-foot road. Both the ditches themselves, and the detour made by the enemy for his own use, were heavily mined with both antitank and armor-piercing mines of standard German pattern.

d. Comment

(1) The substitution of Teller mines for prepared demolition charges in the preparation of booby traps in buildings and cisterns is noteworthy, and affords a further instance of their increasing use with pull-igniters for anti-personnel effect.

(2) In general, the report illustrates the extreme variation in layout of German mine fields, in spite of standard patterns laid down in training pamphlets. In this case, the spacing of 10 feet shown in figure 6 is exceptionally close.