of British patrol and minesweeping
craft, exclusive of the stationary boom defence vessels, was at this
time 3,084. Of this number 473 were in the Mediterranean, 824 were in
the English Channel between The Nore and Falmouth, 557 were in Irish
waters or on the west coast of England, and the remaining 1,230 were on
the east coast of England and the east and west coasts of Scotland and
the Orkneys and Shetlands.

The work of these vessels was almost entirely of an anti-submarine or
minesweeping nature.

The trawlers were engaged in patrol duty, convoy escort service, and
minesweeping. The drifters worked drifting nets fitted with mines as an
anti-submarine weapon, and also in the case of the Dover area they laid
and kept efficient a barrage of mine nets off the Belgian coast. Some
were also fitted with hydrophones and formed hunting flotillas, and some
were engaged in minesweeping duties, or in patrolling swept channels. At
Fleet bases a small number were required to attend on the ships of the
Fleet, and to assist in the work of the base. The whalers, being faster
vessels than the trawlers, were mostly engaged on escort duty or on
patrol. The motor launches were employed for anti-submarine work, fitted
with hydrophones, and worked in company with drifters and torpedo-boat
destroyers, or in minesweeping in areas in which their light draught
rendered it advantageous and safer to employ them instead of heavier
draught vessels to locate minefields, and in the Dover area they were
largely used to work smoke screens for operations on the Belgian coast.

As the convoy system became more general, so the work of the small craft
in certain areas altered from patrol and escort work to convoy duty.
These areas were those on the East Coast and north-west of Scotland
through which the Scandinavian and East Coast trade passed, and those in
the Channel frequented by the vessels employed in the French coal trade.
The majority of these ships were of comparatively slow speed, and
trawlers possessed sufficient speed to accompany them, but a few
destroyers of the older type formed a part of the escorting force, both
for the purpose of protection and also for offensive action against
submarines attacking the convoys, the slow speed of trawlers
handicapping them greatly in this respect.

The difficulty of dealing with submarines may be gauged by the enormous
number of small craft thus employed, but a consideration of the
characteristics of a