Their Finest Hour (34 page)

I
NVASION

NOTE BY THE PRIME MINISTER

Prime Minister to C.-in-C., Home Forces, C.I.G.S., and General Ismay.

10.VII.40.

I find it very difficult to visualise the kind of invasion all along the coast by troops carried in small craft, and even in boats. I have not seen any serious evidence of large masses of this class of craft being assembled, and, except in very narrow waters, it would be a most hazardous and even suicidal operation to commit a large army to the accidents of the sea in the teeth of our very numerous armed patrolling forces. The Admiralty have over a thousand armed patrolling vessels, of which two or three hundred are always at sea, the whole being well manned by competent seafaring men. A surprise crossing should be impossible, and in the broader parts of the North Sea the invaders should be an easy prey, as part of their voyage would be made by daylight. Behind these patrolling craft are the flotillas of destroyers, of which forty destroyers are now disposed between the Humber and Portsmouth, the bulk being in the narrowest waters. The greater part of these are at sea every night, and rest in the day. They would, therefore, probably encounter the enemy vessels in transit during the night, but also could reach any landing point or points on the front mentioned in two or three hours. They could immediately break up the landing craft, interrupt the landing, and fire upon the landed troops, who, however lightly equipped, would have to have some proportion of ammunition and equipment carried onto the beaches from their boats. The flotillas would, however, need strong air support from our fighter aircraft during their intervention from dawn onward. The provision of the air-fighter escort for our destroyers after daybreak is essential to their most powerful intervention on the beaches.

2. You should see the Commander-in-Chief’s (Home Fleet) reply to the question put to him by the desire of the Cabinet, i.e., what happens if the enemy cover the passage of their invading army with their heavy warships? The answer is that, as far as we know at present, they have no heavy ships not under long repair except those at Trondheim,
¹
which are closely watched by our very largely superior forces. When the
Nelson
and
Barham
are worked up after refit in a few days’ time (the 13th and 16th), it would be easily possible to make two forces of British heavy ships, either of which would be sufficiently strong; thus the danger of a northern outbreak could be contained, and at the same time a dart to the south by the Trondheim ships could be rapidly countered. Moreover, the cruisers in the Thames and Humber are themselves strong enough, with the flotillas, to attack effectively any light cruisers with which the enemy could cover an invasion. I feel, therefore, that it will be very difficult for the enemy to place large well-equipped bodies of troops on the east coast of England, whether in formed bodies or flung piecemeal on the beaches as they get across. Even greater difficulties would attend expeditions in larger vessels seeking to break out to the northward. It may further be added that at present there are no signs of any assemblies of ships or small craft sufficient to cause anxiety, except perhaps in Baltic ports. Frequent reconnaissance by the air and the constant watching by our submarines should give timely warning, and our minefields are an additional obstruction.

3. Even more unlikely is it that the south coast would be attacked. We know that no great mass of shipping exists in the French ports, and that the numbers of small boats there are not great. The Dover barrage is being replenished and extended to the French shore. This measure is of the utmost consequence, and the Admiralty are being asked to press it forward constantly and rapidly.
They do not think that any important vessels, warships or transports, have come through the Straits of Dover.
Therefore, I find it difficult to believe that the south coast is in serious danger at the present time. Of course, a small raid might be made upon Ireland from Brest. But this also would be dangerous to the raiders while at sea.

4. The main danger is from the Dutch and German harbours, which bear principally upon the coast from Dover to the Wash. As the nights lengthen, this danger zone will extend northward, but then, again, the weather becomes adverse and the “fishing-boat invasion” far more difficult. Moreover, with cloud, the enemy air support may be lacking at the moment of his impact.

5. I hope, therefore, relying on the above reasoning, which should be checked with the Admiralty, that you will be able
to bring an ever larger proportion of your formed divisions back from the coast into support or reserve, so that their training may proceed in the highest forms of offensive warfare and counter-attack,
and that the coast, as it becomes fortified, will be increasingly confided to troops other than those of the formed divisions, and also to the Home Guard. I am sure you will be in agreement with this view in principle, and the only question open would be the speed of the transformation. Here, too, I hope we shall be agreed that the utmost speed shall rule.

6. Air-borne attack is not dealt with in this note. It does not alter its conclusions.

* * * * *

It will be noted that my advisers and I deemed the east coast more likely to be attacked during July and August than the south coast. There was in fact no chance of either assault during these two months. As will presently be described, the German plan was to invade across the Channel with medium ships (four thousand to five thousand tons) and small craft, and we now know that they never had any hope or intention of moving an army from the Baltic and North Sea ports in large transports; still less did they make any plans for an invasion from the Biscay ports. This does not mean that in choosing the south coast as their target they were thinking rightly and we wrongly. The east-coast invasion was by far the more formidable if the enemy had had the means to attempt it. There could, of course, be no south-coast invasion unless or until the necessary shipping had passed southward through the Straits of Dover and had been assembled in the French Channel ports. Of this, during July, there was no sign.

We had nonetheless to prepare against all variants, and yet at the same time avoid the dispersion of our mobile forces, and to gather reserves. This nice and difficult problem could only be solved in relation to the news and events from week to week. The British coastline, indented with innumerable inlets, is over two thousand miles in circumference, without including Ireland. The only way of defending so vast a perimeter, any part or parts of which may be simultaneously or successively attacked, is by lines of observation and resistance around the coast or frontiers with the object of delaying an enemy and meanwhile creating the largest possible reserves of highly trained mobile troops so disposed as to be able to reach any point assailed in the shortest time for strong counter-attack. When in the last phases of the war Hitler found himself encircled and confronted with a similar problem, he made, as we shall see, the gravest possible mistakes in handling it. He had created a spider’s web of communications,
but he forgot the spider.
With the example of the unsound French dispositions for which such a fatal penalty had just been exacted fresh in our memories, we did not forget the “mass of manoeuvre”; and I ceaselessly inculcated this policy to the utmost extent that our growing resources would allow.

The views in my paper of July 10 were in general harmony with Admiralty thought, and two days later Admiral Pound sent me a full and careful statement which he and the Naval Staff had drawn up in pursuance of it. Naturally and properly, the dangers we had to meet were forcefully stated.

But in summing up Admiral Pound said:

It appears probable that a total of some hundred thousand men might reach these shores without being intercepted by naval forces …
but the maintenance of their line of supply, unless the German Air Force had overcome both our Air Force and our Navy, seems practically impossible…. If the enemy undertook this operation, he would do so in the hope that he could make a quick rush on London, living on the country as he went, and force the Government to capitulate.

The First Sea Lord divided the hundred-thousand maximum figure both as to enemy ports of departure and the possible impact on our coasts as in the following table:

I was content with this estimate. As the enemy could not bring heavy weapons with them, and would speedily have the supply lines of any lodgments cut, the invading strength seemed even in July to be well within the capacity of our rapidly improving army. I remitted the two documents to the Staffs and Home Command.

M
IINUTE BY THE
P
RIME
M
INISTER

15.VII.40.

The Chiefs of Staff and Home Defence should consider these papers. The First Sea Lord’s memorandum may be taken as a working basis, and although I personally believe that the Admiralty will in fact be better than their word, and that the invaders’ losses in transit would further reduce the scale of attack, yet the preparations of the land forces should be such as to make assurance doubly sure.
Indeed, for the land forces the scale of attack might well be doubled, namely, 200,000 men distributed as suggested
[i.e., in the proportion suggested]
by the First Sea Lord.
Our Home Army is already at a strength when it should be able to deal with such an invasion, and its strength is rapidly increasing.

I should be very glad if our plans to meet invasion on shore could be reviewed on this basis, so that the Cabinet may be informed of any modifications. It should be borne in mind that although the heaviest attack would seem likely to fall in the north,
yet the sovereign importance of London and the narrowness of the seas in this quarter make the south the theatre where the greatest precautions must be taken.

There was general acceptance of this basis, and for the next few weeks we proceeded upon it. Upon the action to be taken by our main Fleet in the narrow waters precise orders were issued with which I was in full agreement. On July 20, after considerable discussion with Admiral Forbes, the Commander-in-Chief, the following decisions were promulgated by the Admiralty:

(1) Their Lordships do not expect our heavy ships to go south to break up an expedition landing on our coast in the absence of any reports indicating the presence of enemy heavy ships.

(2) If enemy heavy ships support an expedition, accepting the risks involved in an approach to our coast in the southern part of the North Sea, then it is essential that our heavy ships should move south against them, also accepting risks.

In order to reach more definite conclusions about the varying probabilities and scales of attack on our extended coastline, so as to avoid undue spreading of our forces, I sent the Chiefs of the Staff a further Minute early in August.

D
EFENCE
A
GAINST
I
NVASION

MINUTE BY THE PRIME MINISTER AND MINISTER OF DEFENCE

5.VIII.40.

Bearing in mind the immense cost in war energy and the disadvantages of attempting to defend the whole coast of Great Britain, and the dangers of being unduly committed to systems of passive defence, I should be glad if the following notes could be borne in mind:

1. Our first line of defence against invasion must be as ever the enemy’s ports. Air reconnaissance, submarine watching, and other means of obtaining information should be followed by resolute attacks with all our forces available and suitable upon any concentrations of enemy shipping.

2. Our second line of defence is the vigilant patrolling of the sea to intercept any invading expedition, and to destroy it in transit.

3. Our third line is the counter-attack upon the enemy when he makes any landfall, and particularly while he is engaged in the act of landing. This attack, which has long been ready from the sea, must be reinforced by air action; and both sea and air attacks must be continued so that it becomes impossible for the invader to nourish his lodgments.

4. The land defences and the Home Army are maintained primarily for the purpose of making the enemy come in such large numbers as to afford a proper target to the sea and air forces above mentioned, and to make hostile preparations and movements noticeable to air and other forms of reconnaissance.

5. However, should the enemy succeed in landing at various points, he should be made to suffer as much as possible by local resistance on the beaches, combined with the aforesaid attack from the sea and the air. This forces him to use up his ammunition, and confines him to a limited area. The defence of any part of the coast must be measured, not by the forces on the coast, but by the number of hours within which strong counter-attacks by mobile troops can be brought to bear upon the landing places. Such attacks should be hurled with the utmost speed and fury upon the enemy at his weakest moment, which is not, as is sometimes suggested, when actually getting out of his boats, but when sprawled upon the shore with his communications cut and his supplies running short. It ought to be possible to concentrate ten thousand men fully equipped within six hours, and twenty thousand men within twelve hours, upon any point where a serious lodgment has been effected. The withholding of the reserves until the full gravity of the attack is known is a nice problem for the Home Command.

6. It must be admitted that the task of the Navy and Air Force in preventing invasion becomes more difficult in the Narrow Seas, namely, from the Wash to Dover. This sector of the coast front is also nearest to the supreme enemy objective, London. The sector from Dover to Land’s End is far less menaced, because the Navy and Air Force must make sure that no mass of shipping, still less protecting warships, can be passed into the French Channel ports. At present the scale of attack on this wide front is estimated by the Admiralty at no more than five thousand men.
²
Doubling this for greater security, it should be possible to make good arrangements for speedy counter-attack in superior numbers, and at the same time to achieve large economies of force on this southern sector, in which the beach troops should be at their minimum and the mobile reserves at their maximum. These mobile reserves must be available to move to the southeastern sectors at short notice.
Evidently this situation can be judged only from week to week.

7. When we come to the west coast of Britain, a new set of conditions rules. The enemy must commit himself to the broad seas, and there will be plenty of time, if his approach is detected, to attack him with cruisers and flotillas. The Admiralty dispositions should conform to this need. The enemy has at present no warships to escort him. Should we, for instance, care to send twelve thousand men unescorted in merchant ships to land on the Norwegian coast, or in the Skagerrak and Kattegat, in face of superior sea-power and air-power? It would be thought madness.

8. However, to make assurance triply sure, the Admiralty should pursue their plan of laying a strong minefield from Cornwall to Ireland, covering the Bristol Channel and the Irish Sea from southward attack. This minefield is all the more necessary now that by the adoption of the northabout route for commerce we have transferred a large part of our patrolling craft from the [south-]western approaches, which have become permanently more empty and un-watched.

9. The establishment of this minefield will simplify and mitigate all questions of local defence north of its point of contact with Cornwall. We must consider this sector from Cornwall to the Mull of Cantyre as the least vulnerable to sea-borne invasion. Here the works of defence should be confined to guarding by a few guns or land torpedo tubes the principal harbours, and giving a moderate scale of protection to their gorges.
³
It is not admissible to lavish our limited resources upon this sector.

10. North of the Mull of Cantyre to Scapa Flow, the Shetlands and the Faroes, all lies in the orbit of the main Fleet. The voyage of an expedition from the Norwegian coast would be very hazardous, and its arrival anywhere right round to Cromarty Firth would not raise immediately decisive issues. The enemy, who is now crouched, would then be sprawled. His advance would lie in difficult and sparsely inhabited country. He could be contained until sufficient forces were brought to bear and his communications immediately cut from the sea. This would make his position all the more difficult, as the distances to any important objective are much longer and he would require considerable wheeled transport. It would be impossible to fortify all landing points in this sector, and it would be a waste of energy to attempt to do so. A much longer period may be allowed for counter-attack than in the southeast opposite London.

11. From Cromarty Firth to the Wash is the second most important sector, ranking next after the Wash to Dover. Here, however, all the harbours and inlets are defended, both from the sea and from the rear, and it should be possible to counter-attack in superior force within twenty-four hours. The Tyne must be regarded as the second major objective after London, for here (and to a lesser extent at the Tees) grievous damage could be done by an invader or large-scale raider in a short time. On the other hand, the sea and air conditions are more favourable to us than to the southward.

12. The Combined Staffs should endeavour to assign to all these sectors their relative scales of vulnerability and defence, both in the number of men employed in the local defence of beaches and of harbours, and also in the number of days or hours within which heavy counter-attacks should be possible. As an indication of these relative scales of attack and defence, I set down for consideration the following: