When Submarines Attack in Pairs.—Another strategic scheme that is used to torpedo enemy craft is to work submarines in pairs.
This is not done, as a rule, except where the ships may, in virtue of their armament, prove dangerous to a single submarine and then they are sunk without warning.
Tactics of two different kinds are used in the actual stopping of the craft. The first is for the submarines to lay off from each other at a distance of from three to five miles (as shown at A in [Fig. 63]). Then when the submarine, with her periscope above water, spots an enemy ship, she signals to the other submarine, which is submerged, and gives her the exact speed and course of the armed vessel.
The submarine with her periscope above water cannot be seen by the ship because she is too far off, and the nearby submarine cannot be seen because she is totally submerged; so the first submarine directs the second submarine how to train her torpedo tubes on the enemy ship and when to shoot the torpedoes at her. By these tactics a ship can be sunk without either of the submarines being seen.
The other and second way by which an armed ship can be attacked is by having a pair of submarines travel together, one directly over and separated from the other by a distance of only twenty or thirty feet (as shown in [Fig. 63]).
FIG. 63. A, B, HOW THE SUBMARINES TRAVEL IN PAIRS.
Now, when a ship is sighted by the craft nearest the surface she comes up boldly and demands the hostile vessel to heave to. Should, instead, the enemy ship open fire and cripple or destroy the submarine, the submerged submarine takes up the fight and shoots a couple of torpedoes at the aggressive ship and so puts an end to her, if possible.
The tactics we have told you about are only a couple of the many used by present-day submarines; we should like to go on and write a book about them but if we did we’re afraid the Imperial German Government might not like it, so we’ll stop here.