About the actual achievements of the airplane as a foe to submarines there hangs a haze of mystery. It has been the policy of the Allied governments to keep secret the record of submarines destroyed and particularly the methods of destruction. But we know that a few have met their fate from bolts dropped from the blue. In The Outlook Lawrence La Tourette Driggs, himself a flying man of no contemptible record, describes the method and result of such an attack. After recounting the steps by which a brother airman attained a position directly above a submerged submarine preparatory to dropping his bomb, he says:
Down shot his plummet of steel and neatly parted the waters ahead of the labouring submarine. But it did not explode. I could see a whirling metal propeller on the torpedo revolve as it sank. It must have missed the craft by twenty feet.
Suddenly a column of water higher than my position in the air stood straight up over the sea, then slipped noiselessly back. By all that is wonderful how did that happen?
As we covered the spot again and again in our circling machines, we were joined by two more pilots, and finally by a fast clipper steam yacht. The surface of the water was literally covered with oil, breaking up the ripple of the waves, and smoothing a huge area into gleaming bronze. Here and there floated a cork belt, odd bunches of cotton waste, a strip of carpet, and a wooden three-legged stool. These fragments alone remained to testify to the corpus delicti.
"Philip," I said half an hour later, as the hot coffee was thawing out our insides, "what kind of a civilized bomb do you call that?"
"That bears the simple little title of trinitrotoluol; call it T. N. T. for short," replied Sergeant Pieron.
"But what made it hang fire so long?" I demanded.
"It's made to work that way. When the bomb begins sinking the little propeller is turned as it is pulled down through the water. It continues turning until it screws to the end. There it touches the fuse-pin and that sets off the high explosive--at any depth you arrange it for."
I regarded him steadfastly. Then I remarked, "But it did not touch the submarine. I saw it miss."
"Yes, you can miss it fifty yards and still crush the submarine." He took up an empty egg shell. "The submarine is hollow like this. She is held rigidly on all her sides by the water. Water is non-compressible like steel. Now when the T. N. T. explodes, even some distance away, the violent expending concussion is communicated to this hollow shell just as though a battering ram struck it. The submarine can't give any because the surrounding water holds her in place. So she crumples up--like this."
Pieron opened his hand and the flakes of egg shell fluttered down until they struck the floor.
Gunfire undoubtedly is still the most reliable preventive against submarine attacks. Comparatively small calibred guns can cause serious damage to submarines even by one well directed shot. Submarines have been sunk both by warships and merchantmen in this way and many more have been forced to desist from attacks. Not every merchantman, of course, can be equipped with the necessary guns and gunners. Neither equipment nor men can be spared in sufficient quantities. But the efficiency of gun protection has been proved beyond all doubt by many authentic reports of successful encounters between armed merchantmen and submarines in which the latter were defeated.
Ramming, too, has been advocated and tried. It is, however, a procedure involving considerable danger to the attacking boat. For one thing all the submarine has to do is to dive quick and deep enough and it is out of harm's way. Then, too, the chances are that the submarine can launch a torpedo in time to reach the ramming vessel before the latter can do any damage.
[Illustration: A Critical Moment.
Painting by John E. Whiting.]
There have been reports of submarine duels between Austrian and Italian submarines in the Adriatic in which it was claimed that in each at least one submarine was destroyed, and, at least, in one instance both the duellists were sunk. Generally speaking the fact has been established, however, that submarines cannot fight submarines with any degree of success, except in exceptional cases and under exceptional conditions.
