f assembly a matter of great
importance, owing to the very large number of vessels that were
collected in them. Some of the ports were already in possession of these
defences, but amongst those for which net protection was prepared and
laid during 1917 were Halifax, Sydney (Cape Breton), Falmouth, Lamlash,
Rosslare (on the south-east coast of Ireland), Milford Haven, Sierra
Leone and Dakar. This involved extensive work, and was undertaken and
carried out with great rapidity by Captain F.C. Learmonth and his staff,
whose work in the production of net defences during the war was of
inestimable value, not only to ourselves, but to our Allies, for whom
large supplies of net defences were also provided. The U.S.A. also
adopted our system of net defence for their harbours on entry into the
war. Many anxious months were passed at the Admiralty and at the ports
named until the anti-submarine defences were completed.

The escort of the convoys through the submarine zone imposed very heavy
work upon the destroyers, sloops and other screening vessels. This was
due partly to the fact that there were not sufficient vessels to admit
of adequate time being spent in harbour to rest the crews and effect
necessary repairs, and partly to the nature of the work itself and the
weather conditions under which so much of it was carried out. It will be
realized by those who have been at sea in these small craft that little
rest was obtainable in the Atlantic between the west coast of Ireland
and the mouth of the Channel and positions 800 to 400 miles to the
westward, except in the finest weather. When to this is added the
constant strain imposed by watching for the momentary appearance of a
periscope or the track of a torpedo, and the vigilance needed,
especially on dark and stormy nights, to keep touch with a large convoy
of merchant ships showing no lights, with the inevitable whipping up of
occasional stragglers from the convoy, some idea may be gathered of the
arduous and unceasing work accomplished by the anti-submarine escorts.

It had been my practice during 1917 to call for returns from all
commands of the number of hours that vessels of the destroyer and light
cruiser type were actually under way per month, and these returns showed
how heavy was the strain on the destroyers, particularly those engaged
in convoy work.

For several months, for instance, the destroyers in the flotillas
stationed at Devonport were under way on an average