Now, the word munitions means war materials of every kind—except, of course, men and money; but on a submarine the munitions are limited to (1) the automobile torpedo, which we have described in the last chapter; (2) rapid-fire machine guns, and (3) submarine mines.
In the present war Germany has undertaken the gigantic task of sinking all the merchantmen, not only of the Allies but of the neutral countries as well, and it is this U-boat policy which has brought her into a state of war with nearly every civilized country on the face of the earth.
As the torpedo is such a costly weapon, it would not do to waste it on sinking any but the largest ships, or those carrying valuable cargoes; but the same policy of Germany, which is to starve out the Allies, also calls for sinking the smaller craft, such as trawlers and unarmed merchantmen, and this is done by means of rapid-fire machine guns.
These guns are mounted fore and aft on the deck of the submarine, and they are used to bring down small ships and also to enable the undersea craft to defend herself against submarine chasers, airplanes, or occasionally when she is surprised by a destroyer or other armed ship which may get within firing range and attack her before she has time to dive.
The submarine mine is as old as, or older than, the submarine boat itself; and it was probably the idea of fixing a bomb onto or planting a mine under a ship that led to the actual building of the first underwater craft.
The mine is not, however, an explosive destroyer which is used by the submarine boat; for she could never get close enough to an enemy ship in these days of electric eyes and ears to make use of one. What the submarine does do is to play the peaceful rôle of planting the mines—not with the idea of making two grow where only one grew before but of making one ship less where there was one ship more, and this is done by blowing up the enemy ships which may chance to pass over them.
Arming the Submarine with Guns.—From what has been said above, you will see that by the use of rapid-fire guns poor prizes can be easily and cheaply sunk; further, a small craft always makes a bad target for a torpedo and thus the odds of making a miss and losing a torpedo are very considerable. The use of rapid-fire guns is, then, a very good stroke of business, everything considered.
Again, when a submarine is chased and has no time to dive, she is in a bad way, for she is not fast enough to escape, nor can she stop long enough to aim a torpedo at her foe. It is easy to see, then, why her armament[23] should and does include a couple of rapid-fire guns.
The Need of a Quick-Action Gun.—With these conditions staring them in the face, the designers of submarines have worked hard to equip their craft with not only rapid-firing but, what is equally as important, quick-action guns.
To get a rapid-fire machine gun was easy, for this type had been built by the Maxims these many years; but to get one that could be swung or lowered under the deck so that it would not offer resistance to the water when the submarine was running submerged, and then brought up and into action quickly, was quite a different thing, and inventors are still at work on it.