Fighting the Boche Underground

by H. D. Trounce

Camouflets are employed to a large extent to destroy enemy galleries when they are met below ground. The infantry officers occupying the trenches are always informed of an impending "blow" from the enemy, and dispositions are made to withdraw any troops occupying dangerous positions, such as outlying bombers' posts or automatic-rifle detachments, etc.

All ranks in the mining companies are warned not to create an alarm among the infantry occupying the trenches when enemy "blows" are anticipated. Mining officers, at their discretion, advise the infantry of the state of affairs when there is very active fighting underground and there is danger of casualties among the infantry from enemy "blows." Only in the latter event is it wise to inform them. Under ordinary circumstances, no information should be given. Considerable success in warning infantry of impending mines by the enemy has been reached by the British and French miners. They often estimate the time of enemy mines being blown to within a few hours. On the other hand, the enemy often prepare charges and hold them for long periods before firing.

It is most important to ascertain, by underground listening, the nature of the work done. Determination of the nature of the sounds in listening is of equal importance to their location.

The practice of blowing craters on every occasion in "No Man's Land" is discouraged, generally on account of the fact that it will prove an obstacle in the assault when the next infantry attack takes place.

Many craters are blown for tactical reasons, such as the obtaining of good observation-posts and, in other cases, to obtain enfilade fire from the rim of the craters blown. Previous to blowing these craters, plans will have been made with the infantry to consolidate them as soon as blown. The exact diameter of the crater will have been calculated and the position located in "No Man's Land," and a trench constructed, probably the previous night, which will intersect the rim of the proposed crater. As soon as the mine is blown, the infantry will consolidate their positions on the rims of the craters. Many craters are used to good advantage in the disposal of spoil from near-by mine-shafts. Considerable difficulty is found in obtaining new places in which to dump the spoil, especially on active mining sectors.

Many devices are employed to deceive the enemy when firing. Dummy picks are often suspended in the face of the gallery and operated regularly to imitate picking, etc. Other sounds indicating progress of ordinary work may be simulated in the gallery being charged, or perhaps rather noisy work going on in an adjacent tunnel. A little ingenuity here is advisable. Quite a large number of mines are fired at "stand-to" at dawn or dusk, average time, 4 a.m. or 7 p.m., depending on the time of year. Naturally, it is not wise to make these times regular. The "stand-to" times are common because of the fact that the enemy infantry also occupies his fire steps at these times. Care must be taken to withdraw troops occupying dangerous positions.

In the event of blowing a series of mines under the enemy trenches, plans are devised with the infantry in an endeavor to induce the enemy to occupy his threatened trenches in force. This may be effected by a "false" infantry attack, and other means.

The mine is an irresistible means of launching an attack. In a mined sector, the best troops completely lose their bearings for several seconds after an explosion. These several seconds prevent the machine-guns from firing, and the assailant gains a foothold in the first line, and often in the second. The extent of the underground operations in launching an attack naturally depends upon the size of the offensive, whether it be a battalion, brigade, division, or army offensive. The date has been set for the general attack. Mining units, in consultation with the staff of the forces employed, will elaborate their plans for the mining operations. (The battle of Messines furnished an excellent illustration of the value and use of extensive mining in launching an attack. In these operations, the British miners fired a large number of mines from galleries under the enemy front line, and in some cases below their supports. The charges in these mines varied from 15 to 50 tons each, and were all fired at "zero" hour, the minute at which the infantry goes over the top. Nine hundred and fifty thousand pounds of ammonal were used. Some mines had been charged for fourteen months and others for a year. One charge of 95,000 pounds formed a crater 125 feet deep with 186 feet diameter. The largest crater formed was from a charge of 70,000 pounds, depth of crater 86 feet, diameter 260 feet. These mines were in chalk and clay. The result was a complete demoralization of the enemy, and the first objectives were obtained with very few casualties.) The Germans deserted their lines for half a mile to the rear. These mines were fired on a front of several kilometres. The scheme of the offensive having been planned, galleries are driven under the enemy trenches and all charges laid ready for firing.

Throughout the brigade or unit attacking, all watches carried by officers are synchronized so that at "zero" time all mines are fired simultaneously. Frequently mining units are detailed to go over with the infantry in raids, or follow them over in attacks, for special demolition work, in which event they will usually carry portable charges of high explosives, and destroy enemy mine-shafts, dugouts, etc.