Canada in the Second World War


Western Approaches Tactical Policy, April 1943

Canadian War Museum Archives, 19700068-008



Date:      27th April 1943



The enclosed memorandum showing the Tactical Policy in the Western Approaches Command, is forwarded for information and guidance.

[signed Max Horton]



1. The object as laid down in A.C.I’s is as follows:

“The safe and timely arrival of the convoy at its destination is the primary object of the escort.

Evasion attains the primary object and should therefore be the first course of action considered. Although attempted evasion may attain the primary object, the need for reducing the time spent in dangerous waters and the desirability of reaching, an area of air cover must be considered when planning evasive measures.”


2. The object as laid down has been the subject of a good deal of criticism principally on the grounds that it is not offensive enough. It has also been suggested that Support Groups should be given a different object, namely the destruction of U-Boats. Briefly the arguments of the defensive and offensive schools of thought run as follows:

Defensive If trade can be maintained by the continued passage of convoys in comparative safety, the war can be won by other means. Furthermore, the continued failure of U-Boats to achieve any great measure of success will sap their morale and weaken their determination.
Offensive Failure to destroy the U-boats will enable their numbers to increase to such an extent that we shall eventually be overwhelmed by sheer weight of numbers. The morale of the crews will remain at a high level unless a reasonable number of casualties are inflicted, and as a result their offensive spirit will be sustained at a high pitch.


3. The submarine is an exceedingly difficult type of vessel to locate. It is not therefore possible to search out and attack him in a large area without very considerable forces and a very large expenditure of effort. Ho must therefore be dealt with in those areas where he is bound to concentrate in fairly large numbers, e.g.: his bases, vicinity of convoys, areas of approach to his bases, areas in which it is known by intelligence that he is likely to be present in a reasonable degree of concentration.

4. The morale of the Merchant Service is showing signs of strain and it is therefore undesirable to adopt a policy which accepts the sinking of Merchant Ships as a means of indicating the presence of a U-boat and thus rendering him open to attack.

5. The U-boat is particularly vulnerable to air attack, against which at the moment he has no satisfactory counter measure. His policy for dealing with air attack is at present unformed and he prefers to avoid contact with aircraft altogether if he can.

6. The policy of forcing the enemy to dive, which was held to be the correct one in the past, is no longer always sound. U-boats are frequently more effectively dealt with when on the surface, and provided the escort vessel has adequate speed it is probably preferable to keep the enemy on the surface as long as possible. Asdics is no longer the only weapon against the submarine.

7. The enemy’s policy for attacking convoys is continually changing, largely due to the measures we have taken to deal with his particular methods and due to the introduction of new equipment. It is essential that we should change our tactics in order to meet new forms of attack. About a year ago the enemy was concentrating his effort principally upon surface attack at night, and at first he achieved considerable success with this method. The use of snowflakes and R.D.F. has gradually forced him away from this policy, but it is a fairly safe assumption that he still prefers this method of attack if he can carry it out with a reasonable chance of success. This is one of the reasons why it has been considered undesirable to abolish the use of snowflakes altogether. The night dispositions laid down in A.C.I’s were largely designed to provide an R.D.F. screen round the convoy to prevent this surface approach by the enemy, and operation Raspberry was designed to produce an effective search for the attacker after he had done his work.

It is of interest to note, however, that practically every submarine destroyed during the past year was detected and dealt with prior to attack and there were very few occasions on which a successful kill was effected after attack had taken place. This is probably due to the fact that prior to attack the submarine is committed to a certain course of action for the achievement of his purpose, whereas after attack he can concentrate all his efforts on escape.

8. During recent months there is definite evidence that enemy policy has undergone a change. The following facts are evident in this connection:

(1) All U-boats in contact with the convoy made strenuous endeavours to get ahead of the convoy. The object of this appears to be to enable them to attack submerged if surface attack is deemed to be unlikely to succeed, or if they are forced to submerge by the action of our air or surface forces.
(2) Advantage is taken of the disturbance caused by the first attack to allow successive U-boats to approach the convoy undetected. Thus, even if the first attack is made submerged, or by surfacing inside the screen, the succeeding attackers may attempt penetration on the surface.
(3) Submerged attack or submerged approach is much more frequently attempted than heretofore.
(4) U-boats detected approaching the convoy at night and driven off by the escorts frequently make no further effort to attack during the remainder of the night. This may be due to lack of determination or to the fact that they have lost too much bearing on the convoy.


9. What should be our tactical policy to meet the existing enemy policy? To return once more to the object. It is considered that the object of the close escort must still be the safe and timely arrival of the convoy. This does not mean that the object can only be achieved by purely defensive measures, but it does mean that a reasonable degree of protection must be afforded to the convoy. It must also be accepted that our policy must not entail the use of Merchant Vessels as “bait”. The matter is largely a question of numbers. Whatever form of warfare is considered, the question of the strength of the opposing forces must play a very large part in deciding whether an offensive or defensive role can be adopted. In an extreme case where the number of ships available to escort the convoy is very small, they must adopt a largely defensive role, restricting such offensive measures as they may be able to take to an area around the convoy.

It is proposed to divide the problem up Into two parts (1) By night and (2) By day.

1. By Night

10. It is considered that our policy should be to dispose a reasonable proportion of our force so as to try and prevent an attack being carried out on the convoy and to utilise any balance of our force left over for offensive measures.

11. The question of what constitutes a reasonable proportion to be so allocated for defensive purposes depends upon circumstances, but it is generally considered that the number of vessels so employed should be between six and eight. Under certain conditions and when the enemy threat is not heavy, such vessels may be utilised to make sorties against the enemy but they should not remain long away from the convoy if more than one submarine is known to be in the vicinity. The disposition of this force should be such as to provide, so far as is possible, complete R.D.F. cover with a concentration of force in the sector in which attack is most probable. This sector may vary in size but will, with present enemy policy, normally lie before the beam of the convoy.

12. If the enemy succeeds, in spite of this, in executing an attack, endeavour should be made to locate and sink the U-boat that has delivered this attack by carrying out an offensive search in the area in which he is most likely to be – this operation should not uncover the convoy to the extent of permitting other U-boats to approach and attack the convoy unmolested.

13. In this connection, it should be noted that recent reports show a tendency for U-boats to follow one another in to the attack from the same direction.

14. The proportion of force available after this close screen has been provided should be employed to harass and attack U-boats which are gaining position or waiting to attack on the outskirts of the convoy. This force should be careful not to confuse the close screen by approaching the convoy, unless in pursuit of the enemy.

2. By Day

15. It is considered that our policy should be to dispose a reasonable proportion of our force so as to try and prevent a submerged attack being carried out on the convoy. The size of the force so allocated depends on circumstances, but it is considered that six vessels should normally be sufficient to provide a reasonable degree of security. These vessels may be utilised for making sorties against the enemy and in particular they should do this when the number of U-boats in contact are few or they are known to be too far aft in bearing to be able to deliver a submerged attack. One additional vessel should normally be stationed astern of the convoy to harry stragglers and generally act as “watchdog”.

16. Any vessel over and above the numbers required for providing the cover referred to above should be used entirely for offensive purposes such as chasing up H/F D/F bearings or patrolling at visibility distance from the convoy.

17. If the enemy succeeds in spite of these measures in executing an attack, endeavour should be made to locate and sink the U-boat that has delivered this attack, by carrying out an asdic search in the most likely area where the U-boat maybe. Vessels not forming part of the close screen may be employed in such an operation. This operation should not unduly expose the convoy to attack by further U-boats though this is not considered to be of such importance by day as it is by night.


18. The above policy may have to be varied in order to meet special occasions or peculiar tactics by the enemy. Senior-Officers of Escort Groups have complete freedom to exercise their initiative under all circumstances, and it is not desired that they should be rigidly bound to comply with any of the diagrams or operation orders laid down in A.C.I’s.

It is highly important for Senior Officers of Escort Groups to retain the initiative and not allow the enemy to throw the escort force into confusion.

A sharp watch should be maintained for new tactics on the part of the enemy and an immediate adjustment must be made in our own tactics to meet any such change, once it is detected.

The air provides a strong offensive weapon which, skilfully handled, provides an effective counterpart to the somewhat defensive role that is forced upon the smaller escort groups when no support group is present. This must be born in mind by those who feel that we are not being sufficiently offensive.

A new night operation to replace Raspberry and Half Raspberry is about to be issued for trial. This operation is designed to conform with our policy as laid down in this paper.