It is generally difficult to find ordinary spies who are also
sufficiently imbued with technical knowledge to be of use in gaining
naval or military details. Consequently officers are often employed
to obtain such information in peace time as well as in the theatre of
action in war.
But with them, and especially with those of Germany, it is not easy to
find men who are sufficiently good actors, or who can disguise their
appearance so well as to evade suspicion. Very many of these have
visited our shores during the past few years, but they have generally
been noticed, watched, and followed, and from the line taken by
them in their reconnaissance it has been easy to deduce the kind of
operations contemplated in their plans.
I remember the case of a party of these motoring through Kent
nominally looking at old Roman ruins. When they asked a landowner
for the exact position of some of these he regretted he had not a
map handy on which he could point out their position. One of the
"antiquarians" at once produced a large scale map; but it was not
an English map: it had, for instance, details on it regarding water
supply tanks which, though they existed, were not shown on any of our
ordnance maps!
In addition to the various branches of spying which I have mentioned,
the Germans have also practised commercial espionage on systematic
lines.