A report on British engineering methods of overcoming German antitank obstacles in WWII, from Tactical and Technical Trends, No. 31, August 12, 1943. [DISCLAIMER: The following text is taken from the U.S. War Department publication Tactical and Technical Trends. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]

BRITISH DEMOLITION AND GAPPING OF GERMAN ANTITANK OBSTACLES In the early phases of the present war the German successes were in no small part due to their offensive use of tanks and mechanized equipment. As they have gone on the defensive the Germans have paid equal attention to the development of antitank obstacles. The antitank ditch is one of the principal antitank obstacles, to which the Germans have devoted considerable study. German-designed antitank ditches normally have vertical faces on both sides and not only on the side farthest from the approaching tank. Both faces must be broken down, but the face which the tank must climb up presents the greatest difficulty. The pick and shovel is likely to be the simplest and quickest method of breaking down a vertical face. The shovels should be specially prepared beforehand by bending the heads at right angles to the handle, so that the men can work on a face from inside the trench and pull it down towards them. It will be necessary to use explosives where the soil is hard or the face is high. Various methods have been tried including the placing of charges against the vertical face or dug into the vertical face. Both of these methods have been unsuccessful as the resulting ramp has proved to be far too steep for the tank to climb. The only method that has been universally successful has been the placing of charges as shown in Fig. 1, though it has the disadvantage of exposing the men while placing the charge. In this method a minimum width of gap of 12 feet is required. The charge is placed on the original ground level, or dug in flush with the original ground level and tamped if time permits. Boxes containing 25 pounds of TNT, or equivalent explosive, are placed in a line across the gap desired. If the soil is not too compact, the charges can be placed 9 inches apart. If the soil is hard and compact the boxes containing the charges should be touching so as to increase the total charge. An alternative that has proved successful is the placing of double charges at the ends where the tank tracks will cross (see Fig. 2). The distance from the back of the charge to the edge of the trench should equal one-half of the depth of the face. If the trench is revetted with timber, the revettment must be cut. This is done by dropping the necessary cutting charges of TNT against the revettment in the form of an elongated pole charge. The charge will vary according to the type of revettment. It should be placed one-third of the way up the revettment from the bottom of the vertical face. (see Fig. 1). If the wall is revetted with concrete the sides as well as the bottom of the panel to be blown out will have to be cut with explosives (see Fig. 3). All these charges must be made up beforehand on planks. There should be no economy of struts as close contact with the wall or revettment throughout the charge is important. Unless the thickness of the concrete revettment is accurately known, a larger charge than might appear necessary should be used in order to insure destruction. The charges should be laid end to end in order to get complete cutting action. All charges must be detonated simultaneously including those on top of the trench, on both sides, and the revettment cutting charges. A detonating cap should be used in every 25-pound cratering charge of TNT and at suitable intervals along the revettment cutting charges. The entire demolition setup is interconnected by means of primacord and leads are brought out to a central junction where detonation can be safely initiated. In order to be on the safe side, all primacord mains should be in duplicate. The junction box should be placed so that the detonating waves go forward along the primacord with no undue bends. The explosion which breaks down the sides of the ditch leaves loose pulverized earth ramps on each face and loose earth in the bottom of the trench, which must be leveled off with pick and shovel. The spoil forming the ramps is likely to be very loose and soft, so that tanks will dig themselves in when climbing the ramp and get stuck. It is the rear of the tank's tracks which tend to dig in and belly the tank as it opens its throttle to climb out of the trench. To prevent this, brushwood fascines must be made ready to provide a good surface on the bottom of the ditch and resist the digging in by the rear end of the tank. The fascines are laid crosswise and must be carefully made or they will tend to provide a track that will be too steeply cambered and the tank will slip off sideways. To prevent such sliding the fascines must be made wider at the ends, than in the middle by placing the brushwood, of which the fascines are made, with the thick ends outwards and the thinner parts towards the center (see Fig. 4). To insure strength, the center of the fascines must be very securely and tightly bound with wire. A reserve of fascines must be kept ready in the ditch to strengthen the tank gap as it shows signs of breaking up. It is essential that there be continuous maintenance of the gap while it is in use.

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