uoys,
and it was not completed until the late summer of 1917. Even then it was
not an effective barrier owing to the tidal effects, as submarines were
able to pass over it during strong tides, or to dive under the nets as
an alternative; it was not practicable to use nets more than 60 feet
deep, whilst the depth of water in places exceeded 120 feet.

Deep mines were laid to guard the water below the net, but although
these were moored at some considerable distance from the barrage,
trouble was experienced owing to the mines dragging their moorings in
the strong tide-way and fouling the nets. One series had to be entirely
swept up for this reason. Many devices were tried with the object of
improving this barrage, and many clever brains were at work on it. _And
all the time our drifters with their crews of gallant fishermen, with
Captain Bird at their head, worked day after day at the task of keeping
the nets efficient_.

In spite of its deficiencies the barrage was believed to be responsible
for the destruction of a few submarines, and it did certainly render the
passage of the Straits more difficult, and therefore its moral effect
was appreciable. Towards the end of 1917, however, evidence came into
our possession showing that more submarines were actually passing the
Straits of Dover than had been believed to be the case, and it became a
question whether a proportion of the drifters, etc., required for the
maintenance of the nets of the barrage should be utilized instead for
patrol work in the vicinity of the mine barrage then being laid between
Folkestone and Cape Grisnez. This action was taken, drifters being
gradually moved to the new area.

In April, 1916, a net barrage, with lines of deep mines on the Belgian
side of the nets, had also been laid along the Belgian coast covering
the exits from the ports of Ostend and Zeebrugge as well as the coast
between those ports. These nets were laid at a distance of some 24,000
yards from the shore. This plan had proved most successful in preventing
minelaying by submarines in the Straits of Dover, and the barrage was
maintained from May to October, but the weather conditions had prevented
its continuance from that date.

The operation was repeated in 1917, the barrage being kept in position
until December, when the question of withdrawing the craft required for
its maintenance for patrol work in connection with the minefield laid on
the Folkestone-Grisnez line came under