er-water craft crept in as close, and mined the
fairways. We were ordered to open sea again, to steer the shortest
course by which we could reach a depth of water that could not be mined.
Zigzag progress now assumed the importance that was ever its right. It
had been but cursorily maintained. The 'shortest distance between two
points' had, for so long, been our rule that many masters were unwilling
to steer in tangents. On passage in the more open sea, they were soon
converted to a belief in the efficacy of a crazy course. Statistics of
our losses proved the virtue of the tangent: of a group of six vessels
sunk in a certain area only one--a very slow vessel--was torpedoed while
maintaining a zigzag. Extracts from the diary of a captured submarine
commander were circulated among us, giving ground for our confidence, in
the frequent admissions of failure--"owing to a sudden and unexpected
alteration of course."

Still, we were unarmed. If, by zigzag and a keen look-out, we were
fortunate in evading torpedo attack, the submarine had by now mounted a
surface armament, and we were exposed to another equally deadly offence.
For our protection, Admiralty placed a new type of warship on the
routes approaching the channels. Built originally for duty as
minesweepers, the sloops were faster and more heavily armed than the
drifters. They patrolled in a chain of five or six over the routes that
we were instructed to use. During the daylight hours we were rarely out
of sight of one or other of the vessels forming the chain. Our route
orders were framed towards a definite point of departure into the high
seas when darkness came. There, the patrol of the sloops ended: we had
the hours of the night to make our offing and, by daybreak again, were
assumed to be clear of the 'danger zone.' But the 'danger zone' was
being extended swiftly; it was not always possible to traverse the area
in the dark hours of a night: only the fast liners could stretch out a
speed that would serve. Profiting by experience that was constantly
growing, the _Reichsmarineamt_ constructed larger submarines capable of
remaining long at sea, and of operating in ocean areas that could not
adequately be patrolled. Twelve, fifteen--then twenty degrees of
longitude marked their activity advancing to the westward: they went
south to thirty-five: in time the Mediterranean became a field for their
efforts. Gunfire being the least expensive, they relied on their deck
armame