REFERENCE DOCUMENTS & RESOURCES - OFFICIAL ADMIRALTY DOCUMENTS
ADM 239/261: THE FIGHTING INSTRUCTIONS, 1939 (C.B.04027)
Updated 31-Mar-2007

This document is a modern transcription of a portion of Admiralty record ADM 239/261. This lengthy document contains the Admiralty's official fighting instructions. The original file is held at the The National Archives at Kew, London. This Crown Copyrighted material is reproduced here by kind permission of The National Archives.

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- Pages 35-42 -

SECTION IV.-SHADOWING

CONTENTS

(Note- Click on titles in blue below to view applicable subsections)
Clause Subject
170-171
 
172-175
172
173
174
175
 
176-179
176
177
178
179
 
180-194
180
181-187
188-192
193
194
 
195-200
195-196
197
198
199
200
 
201-205
201
202
203-204
205
 
206-211
206
207
208
209-211
212-219
GENERAL. Click here
 
SELECTION OF SHADOWING FORCES.
By day.
At night.
Submarines
M.T.B's.
 
SHADOWING BY AIRCRAFT.
By day.
At dusk.
At night.
Enemy reports.
 
SHADOWING BY SURFACE VESSELS.
Lookouts
Position from which to shadow.
Range at which to shadow.
Use of asdics in shadowing.
Use of R.D.F. In shadowing.
 
MANOEUVRE WHILST SHADOWING.
First contact.
Time factor.
Alteration of course by the enemy.
Excessive speed and smoke.
Degrees of risk to be accepted.
 
CO-OPERATION BETWEEN SHADOWING VESSELS.
Surrounding the enemy.
Avoidance of bunching.
Shadowing in compass sectors.
Group system of shadowing.
 
REPORTS FROM SHADOWING VESSELS.
Frequency of reports.
Value of complete reports.
"No change" procedure.
Indicating the position of the enemy at night.
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SECTION IV.-SHADOWING

GENERAL

170. The object of shadowing is to supply the Admiral with continuous information of the enemy's movements. The purpose for which this information is required, i.e., the final object of the shadowing, will have a considerable influence on the conduct of shadowing units and should, if possible, be known to them.

171. As long as the primary object of a vessel is to shadow, offensive action which will defeat this object is unsound. When, by retaining touch, there is every prospect of bringing large forces into a position to deliver attacks on the enemy, shadowing vessels should not, generally speaking, take offensive action until after these attacks have been completed. If, however, a favourable opportunity occurs for firing torpedoes unseen at the enemy main force, shadowing vessels should not hesitate to do so. Shadowing may be carried out by surface vessels, submarines or aircraft.

SELECTION OF SHADOWING FORCES

BY DAY
172.
Aircraft provide the normal and most economical means of shadowing by day. They cannot be easily driven off or damaged, and they may provide the only possible means of shadowing a fast enemy force. In certain situations or weather conditions, surface vessels may be required to supplement or replace air shadowing.

AT NIGHT
173.
Small cruisers and destroyers are the most suitable units for night shadowing. They are difficult to see, are quickly manoeuvred and their reports should be accurate. At night, aircraft have difficulty in distinguishing types of ships an in reporting positions with the degree of accuracy required. Successful shadowing can be carried out by aircraft on light moonlight nights and air shadowing is desirable when an air striking force is employed at night.

SUBMARINES
174.
Submarines are not generally suitable for shadowing duties. They are handicapped by having to dive when attacked, and by having insufficient speed for regaining contact or shadowing a fast force. They may be of value in some circumstances, particularly at night, owing to their small silhouette.

M.T.B's.
175.
M.T.B's. are generally unsuitable for shadowing because of their low range of vision, inaccuracies in navigation and engine noise.

SHADOWING BY AIRCRAFT

BY DAY
176.
Shadowing aircraft should make every effort to avoid being detected and driven off. They should keep as far as possible from enemy ships and aircraft, and should make full use of the sun, clouds and conditions of visibility for concealment. No attempt should be made to keep the enemy continuously in sight as there is rarely any difficulty in regaining touch once the approximate position of the enemy is known. When re-sighting the enemy, aircraft should vary the direction of approach.

AT DUSK
177.
The difficulties experienced at dusk by surface shadowing forces make it particularly important that aircraft should maintain touch with the enemy during this period.

AT NIGHT
178.
Aircraft shadowing at night may not be able to conceal their presence, but should keep the enemy main force constantly in sight. Flares and flame floats may be used to assist shadowing and, when required, to indicate the enemy's position to other forces.

ENEMY REPORTS
179.
Instructions for enemy reports by shadowing aircraft are contained in the Signal Manual, Chapter XVII.

SHADOWING BY SURFACE VESSELS

LOOKOUTS
180.
The training and correct stationing of lookouts play an all-important part in the technique of shadowing. Lookouts should be stationed at positions as high up and as low down as possible, consistent with reasonable protection from weather. The eyes of an officer should be kept continuously on the enemy from the moment of sighting. Particular care must be taken that the lookouts on the disengaged side keep a careful watch over their allotted sectors.

POSITION FROM WHICH TO SHADOW
181. By day.
The position from which to shadow by day will frequently be dictated by the disposition of the enemy forces, the position of other shadowing forces and considerations such as the direction of the enemy's base or the relative position of the forces when contact is first gained.

182. When freedom of choice exists, the following considerations should be borne in mind:-

(a) The best position, generally speaking, from which to shadow by day is astern or on the quarter, since the enemy can spare fewer ships for screening abaft the beam than before it, the range can be readily opened, and ships sent to drive off the shadower cannot pursue for long owing to their loss of position. From a position nearly astern alterations of course by the enemy are also easily detected.
(b) Conditions of visibility must, however, be taken into account, and the enemy may have to be kept on the bearing on which he can best be seen, even though this conflicts with other requirements. Under certain circumstances shadowing from to leeward may give advantage in that the enemy's lookout may be hampered by smoke or funnel gases. In bad weather, driving rain, etc., on the other hand, the enemy's lookout may be less efficient to windward.
(c) In heavy weather, destroyers and other light craft should shadow from to leeward. Otherwise they will be run down and destroyed by heavier vessels sent to drive them off.
(d) Shadowing vessels which have not much excess of speed over the enemy may find it advisable to maintain a position ahead or on the bow rather than drop astern, so as to reduce the chances of losing touch altogether if attempts are made to drive them off.

183. At dusk. If weather conditions are favourable, it is desirable to take up a position which will place the enemy in line with the after glow of sunset. From no other position can the enemy be closed with any degree of safety prior to keeping touch during the night.

184. At night. As stated above, it is most important that shadowing vessels should take up a position before dark that will give them the advantage of light. The importance of determination, combined with discretion, on the part of the shadowers if touch is to be maintained as daylight fails is emphasised. It may be expected that the force shadowed will make special efforts to drive off shadowers at this time.

185. The best position from which to shadow at night is dictated almost entirely by conditions of light (moon, stars, horizon) and that position which gives the shadower advantage should be taken up. When conditions of light permit a choice of positions, the following consideration should be borne in mind:-

The position astern or on the quarter is (as by day) generally speaking the best, since in this position it is easier to keep the enemy in sight without risking getting too close ; shadowers are less likely to be seen ; they tend to come up on the enemy if he alters course without increasing speed and they will not interfere with friendly destroyers attacking from ahead.

186. It is advisable for a shadowing vessel to change her position at intervals at night, not only so as to retain the best light conditions but also so as to avoid her position becoming known after reports have been made.

187. At dawn. It is important to be to the westward before dawn, so as to have the advantage of light when opening the range at dawn.

RANGE AT WHICH TO SHADOW
188. Shadowing unseen.
The surest way to avoid being driven off is to remain unseen. It may be possible to keep the enemy in sight and avoid being seen, if lookouts are better trained than the enemy's and use better glasses. However, to reduce the chances of the enemy sighting a shadowing vessel, the latter should normally keep outside visibility distance and close in from time to time to obtain the necessary information ; great patience is required in this method of shadowing. A shadower (especially a destroyer or submarine) right astern of an enemy and kept end-on has a good chance of remaining unseen.

189. By day. When possible, shadowing vessels should remain outside gun range by day. When this is impracticable owing to reduced visibility, the enemy should be approached at high speed at intervals and the range opened again as soon as observations have been made.

190. At night. It is clearly impossible for shadowing vessels to remain outside gun range at night, and their safety must consequently depend primarily on their remaining unseen.

191. When an enemy is aware that he is being shadowed from astern, he may try and close the range by reducing speed or turning directly towards the shadowing ship behind smoke. A ship or ships may be detached from the screen to engage shadowers. Shadowing vessels must be on their guard against such manoeuvres.

192. It will always be difficult to maintain touch without coming under the fire of a superior force. This calls for skill, intelligent anticipation and the best use of the conditions of light, particularly when this is changing. Guns and searchlights should be kept trained on the enemy ready for immediate action. Shadowing vessels should be prepared to make defensive smoke.

USE OF ASDICS IN SHADOWING
193.
The possibility of maintaining touch with the enemy by asdics must be borne in mind. At night or under conditions of low visibility, and when accurate reports of course are not essential, and enemy vessel may be shadowed by this method without undue risk to the shadowing ship.

USE OF R.D.F. IN SHADOWING
194.
R.D.F. Can be used for detecting surface ships at at distance of five miles, and thereafter to assist shadowing up to eight miles. It has a blank zone inside four to five miles. R.D.F. cannot distinguish between a large ship end-on and a small ship broadside on. Further experience is required before R.D.F. Can be considered a practical means of shadowing, though it may be of considerable assistance at night or in low visibility by day.

MANOEUVRE WHILST SHADOWING

FIRST CONTACT
195.
On receipt of a first enemy report at night from an adjacent ship, or on first sighting a suspicious object, immediate avoiding action should be taken and subsequently the enemy closed carefully. If it is then found that the shadowing vessel is abaft the enemy's beam, it will be comparatively easy to keep end-on, reducing speed as necessary to reach a position suitable for shadowing. If the enemy is advancing towards the shadowing ship, prompt avoiding action will again be required and the temporary increase of silhouette during a turn away may have to be accepted. If there is any possibility that the enemy is closing, ships shadowing should not stop of reduce speed to such an extent that their ability to manoeuvre is seriously affected.

196. At night it is most difficult to estimate accurately the enemy's course, and a false impression may be obtained from a column of ships stationed on a line of bearing.

TIME FACTOR
197.
After first contact with an enemy, it is important for shadowing vessels to make allowance for the time that is likely to elapse before an attack on the enemy can develop. The position rather than the actual movements of an enemy force may be the only information required for a considerable period and shadowing vessels should adjust their tactics accordingly. When attack by a striking force is imminent, or fleets are about to make contact, the frequent reporting of enemy movements may be of the highest importance. It may then become necessary for shadowing units to reduce distance in order to increase the accuracy of their reports.

ALTERATION OF COURSE BY THE ENEMY
198.
When an alteration of course by the enemy is observed and the direction is unknown, it should be assumed that the alteration is towards the shadowing vessel. Alterations of course can best be detected by plotting a succession of compass bearings of an enemy.

EXCESSIVE SPEED AND SMOKE
199.
Excessive speed is liable to make a conspicuous bow or stern wave and to betray the presence of the shadowing ship. As shadowing frequently requires sudden alterations of speed, great care is necessary to prevent the emission of puffs of smoke, which are very liable to disclose the position of the shadowing ship.

DEGREES OF RISK TO BE ACCEPTED
200.
In deciding what risk of damage to accept to avoid being driven off, shadowing vessels must be guided by their knowledge of the general situation and the following considerations:-

(a) If no other friendly vessels are in the vicinity and damage would result in touch with the enemy being lost altogether, it may be advisable to withdraw in the first instance in the hope of regaining touch later.
(b) In certain circumstances, such as during the later stages of an approach by day, or when an attack by friendly destroyers is about to develop by night, risk of total destruction may be preferable to losing touch if thereby the movements of the enemy can be reported for a short period.

CO-OPERATION BETWEEN SHADOWING VESSELS

SURROUNDING THE ENEMY
201.
Where more than one ship is available for shadowing, they should be widely separated to that separate forces are required to drive them off. When a number of shadowing vessels have succeeded in encircling an enemy force, touch will not be lost however much the enemy alters course. Those that lose touch will be able to regain it from the reports received from the remainder. When the enemy is surrounded, all ships can afford to keep at a greater distance than in the case of a single vessel.

AVOIDANCE OF BUNCHING
202.
There is usually a most favourable position for shadowing, which all ships would like to use. Consequently, the natural tendency for shadowing ships to "bunch" must be avoided. When deciding on the alternative positions to be assumed, consideration must be given to the possible movements of the enemy and the change in direction of the sun or moon. In general, when more than one ship is shadowing, the natural inclination for each ship to keep the enemy continually in sight should be resisted.

SHADOWING IN COMPASS SECTORS
203.
In order to prevent the bunching of shadowing craft in one position relative to the enemy, use should be made of the appropriate signals in the Fleet Signal Book, to distribute vessels in the different compass sectors. Once W/T silence has been broken to make an enemy report, or if forces were in sight on one another at dusk, W/T may be used as necessary to co-ordinate the movements of shadowing vessels. The danger that signals may be used for D/F purposes must be accepted, in view of the advantages to be gained from proper team work.

204. The sectors to be occupied will normally be those astern, on the quarters and each beam of the force being shadowed. It will usually be unnecessary for more than one or two shadowing vessels to be in contact at any one time, but all must close in periodically to visibility distance to confirm their reckoning or to take over enemy reporting. Shadowing vessels in excess of the numbers required to fill all the sectors should take up stand-by position, at visibility distance from and outside one of the shadowers in touch, but not in a direct line with her and the enemy.

GROUP SYSTEM OF SHADOWING
205
. If there is a danger of a weak shadowing vessel being driven off, or of a larger vessel being surprised and brought under superior gunfire, ships of different types may be detailed to work together as a group. It is then the duty of the smaller ship in the group to maintain touch with the enemy, so as to permit the larger ship to keep at a greater distance. It is the duty of the larger ship to act in support of the smaller and to prevent the latter being driven off by the enemy's screen. The manoeuvring powers of the smaller ship may be superior to those of the larger, and the latter may be unable to maintain visual touch if sudden and drastic alterations of course are made.

FREQUENCY OF REPORTS
206.
The following considerations determine the frequency at which enemy reports should be made by shadowers:-

(a) Likelihood of the enemy knowing that he is being shadowed.
(b) Number and accuracy of reports by other vessels.
(c) The imminence of attack by a striking force or contact with the main forces.
(d) The probable efficiency of W/T communications.
The Admiral should not be left in doubt as to whether the enemy is still being shadowed, or touch as been lost.

VALUE OF COMPLETE REPORTS
207.
Unless the shadowing ship is astern, the least accurate part of the report will probably be the course of the enemy. Consequently, it is far more useful for the recipient to have a succession of complete reports from which to plot the enemy's track, than to have a series of amplifying reports relating to the course of the enemy.

"NO CHANGE" PROCEDURE
208.
The "no change" procedure may be used, when the danger of being located by D/F and of being driven off and losing touch is greater than the need for frequent reports (see Signal Manual, Chapter, XVII).

INDICATING THE POSITION OF THE ENEMY AT NIGHT
209.
Occasions may arise when it is necessary for a shadowing vessel to indicate to a striking force or the main force the approximate position of the enemy. Either starshell or searchlights may be used and a group is provided in the Fleet Signal Book for ordering this procedure.

210. A searchlight had the disadvantage of betraying to the enemy the position of the shadowing vessel and possibly of providing a point of aim. A searchlight burnt vertically may be seen at a considerable distance, and there is no danger of other shadowing vessels being illuminated.

211. The use of starshell for advantage for long ranges and on bright moonlight nights. If low clouds are present, the distance at which starshell can be seen will be considerably reduced. There is a danger that friendly ships will be illuminated.

212. (Blank)

213-219. (Blank)

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