to death. The "scooters" and
"Porte's babies," as we saw in Chapter XXIV, were, however, even better
than these swarming "chasers."

The enormous steel nets were also used more than ever. You can fancy
what they were like by thinking of a gigantic fishing-net many miles
long, with armed steamers instead of floats. In the entrances to some
harbours there were sea-gates made by swinging open a bit of the net by
means of its steamers to let traffic go through, and then swinging it
back again. The mine-fields were made bigger than ever; it was then
that the vast one, mostly laid by the Americans, was begun from the
Orkneys to Norway. Mines were also laid by British submarines and by
daring fast surface mine-layers round Heligoland and other places off
the German coast. In this way the waters in which submarines could
work were made narrower and narrower and were better and better guarded.

But more and more submarines were launched, and they still sneaked out
to sea along the Dutch and Norwegian coasts where the Navy could not
stop them because they used to slink through "territorial waters," that
is, within three miles of the coast, where the sea belonged to the
nearest country, just the same as the land. The Navy, however, had
lines of patrols always on the watch from the Orkneys to the Shetlands,
on to Iceland, over to Norway, and north to the Arctic ice. The narrow
waters of the English Channel were watched by the famous Dover Patrol
under Sir Roger Keyes. From Folkestone to Cap Griz Nez in France there
was an unbroken line of the strongest searchlights on vessels anchored
to ride out the biggest gales. Seven miles west was another line.
Between were hundreds of patrol boats always ready, night or day, to
fire at anything on the surface or to drop depth charges on anything
that dived. A depth charge is a sort of mine that can be set to go off
at a certain depth, say thirty to sixty feet down, when it makes a
sea-quake that knocks the submarine out of gear and sinks it, even if
it does not actually hit it. Besides all these guards on the surface
there were nets and mines underneath. That is why the British army in
France never had its line of communication with England cut for one
single day all through the war.

Now and then the Germans tried a destroyer raid from their ports on the
Belgian coast, or even from their own coast; for they would sneak
through Dutch waters within the three-mile limit as well a