Let us for the moment change the term "spy" to "investigator" or
"military agent." For war purposes these agents may be divided into:
1. _Strategical_ and diplomatic _agents_, who study the political and
military conditions in peace time of all other countries which might
eventually be in opposition to their own in war. These also create
political disaffection and organise outbreaks, such, for instance,
as spreading sedition amongst Egyptians, or in India amongst the
inhabitants, or in South Africa amongst the Boer population, to bring
about an outbreak, if possible, in order to create confusion and draw
off troops in time of war.
2. _Tactical_, military, or naval _agents_, who look into minor
details of armament and terrain in peace time. These also make
tactical preparations on the spot, such as material for extra bridges,
gun emplacements, interruption of communications, etc.
3. _Field spies_. Those who act as scouts in disguise to reconnoitre
positions and to report moves of the enemy in the field of war.
Amongst these are residential spies and officer agents.
All these duties are again subdivided among agents of every grade,
from ambassadors and their attachés downwards. Naval and military
officers are sent to carry out special investigations by all
countries, and paid detectives are stationed in likely centres to
gather information.
There are also traitor spies. For these I allow I have not a good
word. They are men who sell their countries' secrets for money.
Fortunately we are not much troubled with them in England; but we have
had a notorious example in South Africa.