emy waters, including a night attack on the enemy's light cruisers
known to lie occasionally in the Ems River, an operation that it was
intended to carry out in the spring of 1918. A daylight operation in
this neighbourhood, which was carried out during 1918, did not, from the
published reports, meet with success, the coastal motor boats being
attacked by aircraft, vessels against which they were defenceless. The
new boats were of an improved and larger type than the original 40-feet
boats. Delays occurred in construction owing principally to the
difficulty in obtaining engines by reason of the great demand for
engines for aircraft, and but few of the new boats were delivered during
the year 1917.

MINING OPERATIONS

The policy which was carried out during 1917 in this respect, so far as
the supply of mines admitted, aimed at preventing the exit of submarines
from enemy ports. Incidentally, the fact that we laid large numbers of
mines in the Heligoland Bight rendered necessary such extensive sweeping
operations before any portion of the High Sea Fleet could put to sea as
to be very useful in giving us some indication of any movement that
might be intended. In view of the distance of the Grand Fleet from
German bases and the short time available in which to intercept the High
Sea Fleet if it came out for such a purpose as a raid on our coasts, or
on convoys, the information thus gathered would have proved of great
value.

In planning mining operations in the Heligoland Bight, it was necessary
to take into consideration certain facts. The _first_ was the knowledge
that the Germans themselves had laid minefields in some portions of the
Bight, and it was necessary for our minelayers to give such suspected
areas a wide berth. _Secondly_, it was obvious that we could not lay
minefields in areas very near those which we ourselves had already
mined, since we should run the risk of blowing up our own ships with our
own mines.

Mining operations had necessarily to be carried out at night, and as
there were no navigational aids in the way of lights, etc., in the
Heligoland Bight, the position in which our mines were laid was never
known with _absolute_ accuracy. Consequently an area in which we had
directed mines to be laid, and to which a minelayer had been sent, could
not safely be approached within a distance of some five miles on a
subsequent occasion.

The use in mining operations of the device known as "taut wire" ge