some 80 miles. As this distance could be covered in any
direction in open waters such as the North Sea, it is obvious that only
a very numerous force of destroyers steaming at high speed could cover
the great area in which the submarine might come to the surface. She
would, naturally, select the dark hours for emergence, as being the
period of very limited range of vision for those searching for her. In
confined waters such as those in the eastern portion of the English
Channel the problem became simpler. Requests for destroyers constantly
came from every quarter, such as the Commanders-in-Chief at Portsmouth
and Devonport, the Senior Naval Officer at Gibraltar, the Vice-Admiral,
Dover, the Rear-Admiral Commanding East Coast, and the Admiral at
Queenstown. The vessels they wanted did not, however, exist.

Eventually, with great difficulty, a force of six destroyers was
collected from various sources in the spring of 1917, and used in the
Channel solely for hunting submarines; this number was really quite
inadequate, and it was not long before they had to be taken for convoy
work.

Evidence of the difficulty of successfully hunting submarines was often
furnished by the experiences of our own vessels of this type, sometimes
when hunted by the enemy, sometimes when hunted in error by our own
craft. Many of our submarines went through some decidedly unpleasant
experiences at the hands of our own surface vessels and occasionally at
the hands of vessels belonging to our Allies. On several such occasions
the submarine was frequently reported as having been sunk, whereas she
had escaped.

As an example of a submarine that succeeded not only in evading
destruction, but in getting at least even with the enemy, the case of
one of our vessels of the "E" class, on patrol in the Heligoland Bight,
may be cited. This submarine ran into a heavy anti-submarine net, and
was dragged, nose first, to the bottom. After half an hour's effort,
during which bombs were exploding in her vicinity, the submarine was
brought to the surface by her own crew by the discharge of a great deal
of water from her forward ballast tanks. It was found, however, that the
net was still foul of her, and that a Zeppelin was overhead, evidently
attracted by the disturbance in the water due to the discharge of air
and water from the submarine. She went to the bottom again, and after
half an hour succeeded in getting clear of the net. Meanwhile the
Zeppelin had co