rior experience, observation, and acquaintance unquestionably
warrant otherwise.

(iv) Information and counter-information measures. Operations of war
are tremendously affected by the information which each belligerent
possesses of the others. It is therefore of vital importance to weigh
the efficiency of the belligerents in the employment of means of
obtaining, denying, and utilizing information.

There may appropriately be considered present, probable, or possible
use or non-use of indirect methods such as: study of press, captured
documents, and material; reports from other friendly units;
interrogation of prisoners of war, deserters, inhabitants, and escaped
or exchanged prisoners; radio direction-finding; efficiency of
cryptography; interception of enemy radio, telegraph, telephone, and
mail communications; espionage; censorship; propaganda; efficiency of
communications systems, ashore and afloat, which include all means of
interchange of thought. In this connection it will be recalled that
information, however accurate and appropriate, is useless if it cannot
be conveyed in time.

The direct methods of obtaining information are military operations
intended for that purpose, such as observation, reconnaissance,
scouting, trailing.

Counter-information measures are no less important than those
pertaining to collection of information. Such measures include all
provisions for secrecy, such as censorship, counter-espionage,
cryptography, control of own communications, security of documents,
camouflage, and applicable tactical operations.

(b) Factors More Directly Applicable to Armed Forces, (i) Vessels,
including aircraft. The numbers and characteristics, of the ships and
aircraft of the various nations of the world are known with less and
less accuracy from the time when war becomes a probability. The
information available is given intense and comparative scrutiny, under
the specific headings of the factors of the Estimate Form as later
enumerated.

(ii) Land forces, including land-based aviation. Important facts
concerning the land forces of the enemy, including his land-based
aviation, will be known, probably, to a lesser extent than in the case
of the naval forces. The value of a comparison--naval, land, or
air--may depend upon whether the intelligence service has improved the
accuracy of these data, maintained them up to date, and collected
accurate additional information.

(iii) Personnel. The status o