e of these will enable the reader to draw on his own
imagination for the remainder. A vessel was steaming in from the
Atlantic and was about a hundred miles from the Cornish coast when she
was attacked by a submarine above water. The surface ship was heavily
armed, but instead of using her weapons at once she sent out frantic
wireless signals for assistance. Every few minutes the call went far and
wide in plain Morse.

The shells from the submarine splashed into the sea around, but none
struck the target for some minutes. Had the surface ship desired, she
could in all probability have avoided the under-water craft by using her
superior speed, but instead she dropped back, allowing the submarine to
catch up to her, and the shells began to burst unpleasantly close.

Still the frantic wireless calls went forth. First the simple message:
"I am being attacked by a large German submarine." Then the vehemence
increased to: "I am being heavily shelled." A few minutes elapsed and
then the call: "Help. Submarine gaining on me." And finally: "Abandoning
ship."

At this point the submarine was close astern and the liner slowing down
preparatory to lowering her life-boats. The shells were damaging her
superstructure, but a heavy swell interfered with the German
marksmanship. Then came the surprise. A life-boat on the liner's poop
was hoisted clear of the deck and from under its cover there appeared
the lean grey muzzle of a 4.7-inch gun. A few sharp blasts of cordite
and the submarine sagged and disappeared.

The captain of the liner had noticed when first attacked that the
submarine was fitted with wireless and the calls sent out by him were in
_plain Morse code_. On the strength of these the German commander had
saved his torpedoes but lost his ship.

* * * * *

Another form of anti-submarine tactics was the employment of indicator
and mined nets around an apparently disabled ship, or in lines across
narrow channels known to be used by German submarines on their way to
and from their bases. This method has, however, received full mention
in other chapters.

* * * * *

What may be termed the third system of anti-submarine warfare was the
use of extensive mine barriers, specially laid to catch submarines
attempting to pass through them under water. The surface of the sea was
patrolled by shallow-draft vessels and the under-seas guarded by mines.
If a submarine w