craft and at night lighted by the rays of many searchlights,
while the under-seas were almost impassable with mines.

If, however, notwithstanding these defensive systems, a submarine
succeeded in passing through and getting to work on the lines of
communication with the armies in France, there were hydrophone
organisations and patrols all down the Channel from the lighted barrage
to the Scilly Islands. By this means a U-boat would be seldom out of the
hearing of these instruments for more than an hour or so at a time.

The success which attended the perfecting of this vast system was such
that German submarines based on the Flanders coast gave up attempting to
pass down the English Channel. They tried to go to and from their
hunting grounds on the Atlantic trade routes round the north coast of
Scotland. Here the great northern systems took their toll.

During the first nine months of the year 1918 the German submarine
flotillas at Zeebrugge and Ostend lost thirty vessels, and no less than
fifteen of these had, at the time of the signing of the Armistice, been
discovered lying wrecked under the lighted barrage.

CHAPTER XIV

OFF TO THE ZONES OF WAR

HITHERTO I have dealt with the scientific training of the personnel, the
armament and the general organisation of the anti-submarine fleets,
leaving it to the imagination of readers to invest the bare recital of
facts with the due amount of romance. If, however, a true understanding
of this most modern form of naval war is to be obtained, the human
aspect must loom large in future pages.

War, whether it be _on_ the sea, _under_ the sea, on the land or in the
air, is a science in which the human element is of at least equal
importance with that of the purely mechanical. It is a science of both
"blood and iron."

The armed motor launches described in earlier pages, after being built
in Canada to the number of over 500, and engined by the United States,
were transported across the Atlantic on the decks of big ocean-going
steamships--more than one of which was torpedoed on the voyage. On their
arrival in Portsmouth dockyard the guns and depth charges were placed
aboard and the vessels thoroughly equipped and fitted out for active
service.

Officers and men were drafted from the training establishments of the
new navy at Southampton, Portsmouth, Chatham, Greenwich and elsewhere.
Each little vessel was given a number, and within a few weeks of their
arrival fr