stroyers of the 30-knot class would have the greatest difficulty in
facing the heavy weather, and very urgent representations were made by
Sir Frederick Brock for their replacement by more modern vessels before
the winter set in. All that could be effected in this direction was
done, though at the expense of some of the Channel escorts. Urgent
requests for good destroyers were being received at the Admiralty from
every Command, and it was impossible to comply with them since the
vessels were not in existence.

Certain other steps which may be enumerated were taken in connection
with the Scandinavian traffic.

The convoys received such additional protection as could be given by the
airships which were gradually being stationed on the East Coast during
the year 1917, and decoy ships occasionally joined the convoys in order
to invite submarine attack on themselves. This procedure was indeed
adopted on all convoy routes as they were brought into being, the rule
being for the decoy ship to drop behind the convoy in the guise of a
straggler.

Some of our submarines were also detailed to work in the vicinity of
convoy routes in order that they might take advantage of any opportunity
to attack enemy submarines if sighted; due precautions for their safety
were made.

Among the difficulties with which the very energetic and resourceful
Admiral Commanding the Orkneys and Shetlands had to contend in his
working of the convoys was the persistent mining of the approach to
Lerwick Harbour by German submarines; a second difficulty was the great
congestion that took place in that harbour as soon as bad weather set in
during the autumn of 1917. The weather during the latter part of 1917
was exceptionally bad, and great congestion and consequent delay to
shipping occurred both at Lerwick and in the Norwegian ports. As the
result of this congestion it became necessary to increase largely the
number of ships in each convoy, thereby enhancing the difficulty of
handling the convoy.

At the commencement it had been decided to limit the size of a
Scandinavian convoy to six or eight vessels, but as the congestion
increased it became necessary to exceed this number considerably,
occasional convoys composed of as many as thirty to forty ships being
formed. A contributory cause to the increase in the size of convoys was
due to the fact that the trade between Lerwick and the White Sea, which
had been proceeding direct between those places duri