In prewar staff studies this had always been the textbook answer to this particular problem and when, on 23 May 1939, Hitler had informed his generals of his decision to attack Poland, he had predicted that, once Holland, Belgium and France had been occupied, Britain could be blockaded at close range by aircraft flying from bases in those countries and at longer range by U Boats operating from French ports. On 9 October, a month after the war had begun, another top-level directive confirmed that to secure bases for this purpose was one of the aims of ‘Operation Yellow’, the attack on France, and the policy of defeating Britain by destroying her trade and starving her into surrender, which had come close to success in 1917, was reaffirmed in another order, signed personally by Hitler on 29 November.
The first actual examination of the strategy needed to invade Britain was made by the Naval Staff Operations Division, whom Admiral Raeder ordered to look into the subject on 15 November 1939. Its report, submitted to him two weeks later, very understandably stressed the difficulties
of the operation. The geography of the British Isles, they pointed out, favoured the defence, and excellent internal communications would make it easy to concentrate reinforcements against any German forces which did secure a foothold. It would undoubtedly be essential, before any landing of troops was attempted, to destroy the British Air Force and the Navy would still need to protect the invasion fleet by deploying a strong force of escort vessels on either flank and by laying extensive minefields. The Navy’s proposals raised for the first time one problem to which much thought was to be devoted in the next few months: should the attack be mounted from German bases on the North Sea, or even
in
the Baltic via the Kiel Canal, which would make embarkation much easier and reduce the chance of the British discovering, and interfering with, the vast preparations needed, but would mean a long sea crossing, increasing the risk of interception at sea and forfeiting the advantage of surprise ? Or should the fleet sail from French and Dutch ports, more vulnerable to reconnaissance and aerial and naval attack, but offering a short sea crossing and making it easier for the Luftwaffe to provide air cover? The answer to this question largely dictated the answer to the second basic decision: where should the attack be directed ? The short sea route meant the troops disembarking in Kent and Sussex, convenient for a thrust towards London but likely to be heavily defended and with relatively few ports and beaches suitable for landing, due to the area being commanded by cliffs with high ground, favouring the defenders, a little way inland. The long sea route would point to disembarking along the East Coast, with, between the Tyne and the Thames, at least thirteen excellent harbours, such as Blyth and Harwich, and a wide variety of suitable beaches all the way from Filey and Bridlington to Cromer and Clacton. The flat countryside here would make securing a bridgehead, and the subsequent break-out, easier though it was further to the enemy capital. Due to the gently sloping coastline along the East coast, however, the water tended to be shallow close in, with few sheltered bays, so the larger transports would have to lie off shore, exposed to the risk of attack, while discharging their cargoes into smaller lighters and barges, a slow and hazardous business even if the weather were favourable. The Navy nevertheless favoured the North Sea/East coast route, while clearly hoping the operation would never be necessary at all. The High Command, they urged, should not ‘neglect, for the distant object of a possible landing, opportunities which are readily available for damaging the enemy’, and the planners laid down one essential precondition for success: ‘It seems to be indispensable that airborne troops should establish a bridgehead for landing.’ But, if this and other requirements were fulfilled, they were
cautiously optimistic, conceding that ‘when forces are released from the Western Front… a landing in the British Isles, undertaken across the North Sea on a grand scale, … appears to be a possible expedient for forcing the enemy to sue for peace’.
Not long afterwards it was the German Army’s turn and on 13 December, while the civilians in Great Britain and the British Expeditionary Force in France were settling down to that first, cold, dark, miserable winter of the war, the Army Commander-in-Chief, General von Brauchitsch, ‘ordered an examination of the possibility of a landing in England … in a study to be called “North-West” ‘,the code-name which continued to be used for the invasion plans until July 1940. By now the German commanders knew that Holland, as well as Belgium and France, was to be attacked in the Spring Offensive, an important addition, for the Dutch ports and estuaries offered far better facilities for assembling barges and embarking troops and supplies than those so far available. The use of Holland as a base also made more attractive the idea of a ‘middle route’ aimed solely at East Anglia, and the Army favoured a landing on the East coast between the Wash and the Thames, involving some sixteen divisions. The plan was to capture Yarmouth and Lowestoft in a sudden combined sea and air assault, with further landings at Dunwich and Hollesley Bay. Two infantry divisions would land north of the Humber and advance towards the industrial area around Leeds, but this would be essentially a diversion, for the real thrust would come further south, where some four infantry divisions, with airborne support, would clear the way for two panzer divisions and a motorised division. These, it was hoped, would break through the British defences and sever London’s communications with the North, the force’s flank being protected by airborne troops landed on a captured airfield near Cambridge. Other forces would follow in later waves and, once the Germans had built up an overwhelming force, it would move on London, the capture of which would lead, they believed, to the collapse of the whole defence system.
Although the reputation of the Army General Staff stood high, the Army’s confidence in its plan was not wholly shared by the other two services. The Naval Staff, perhaps recalling the defeat of the
Graf Spee
off Montevideo, displayed in its comments a healthy respect for the Royal Navy. ‘The British Home Fleet will always be able to appear in greater strength than our own fleet, if the will is there’, it advised despondently. Whatever support the German Navy received from the Luftwaffe it could not guarantee ‘continuous control of the supply lines’, and, it pointed out in a masterly understatement, it could not ‘be assumed … that the major part of the enemy forces will be incapable of action’ while the landing was
in progress. Finally, the Naval Staff recalled what the soldiers seemed largely to have overlooked, that the ships needed to carry this force of men and vehicles across the North Sea did not exist. ‘The transport required for the forces specified by the General Staff amounts to about 400 medium-sized steamers, with in addition a large collection of auxiliary vessels of the most varied nature, some of which must first be constructed.’ And this was only to carry the first wave of seven divisions. In fact, concluded the sailors gloomily, to mobilise such a force would mean that ‘during the period concerned all other shipping activity is virtually suspended’, while to assemble ships needed in the number, and with the equipment required, ‘presupposes that at least one year previously certain measures have been taken in the dockyards’. It was the classic reply of the Irishman asked the way: ‘If I wanted to go there I wouldn’t have started from here.’
The Luftwaffe, too, perhaps also fearful of being made the scapegoat for failure by the Army, threw cold water on the ‘North-West’ proposals, and the two other services abandoned their own rivalry to combine against the common enemy. ‘The Airborne landing planned’, warned the Air Staff in a note sent to the Army on 30 December 1939 and previously seen by the Naval Staff Operations Division, ‘will run into the strongest point of the enemy air defence, which it will not be possible to eliminate.… The planned operation can only be considered … under conditions of absolute air superiority, and even then only if surprise is ensured…. Even weak enemy forces would suffice to make transport almost impossible…. A combined operation with a landing in England as its object must be rejected.…It could only be the last act of a war against England which had already taken a victorious course, as otherwise the conditions required for the success of a combined operation do not exist.’ Here again was that circular argument to which so many discussions had already returned: an invasion could only take place successfully when it was no longer necessary.
And then, far sooner than the German generals had themselves expected, the situation changed dramatically. In April 1940 Denmark and Norway, in May Belgium and Holland, were overrun. On 4 June the last British soldier was lifted from the beaches of Dunkirk and two weeks later, on Monday, 17 June, France asked for an Armistice. The whole of the coastline of north-west Europe, from the north of Norway to the Spanish frontier, now lay in German hands, and the booty which had fallen to the victors was enormous. Though much had been rendered temporarily unusable, the British Expeditionary Force had inevitably abandoned enormous numbers of guns and vehicles and vast mounds of supplies of all
kinds, while the French had not even attempted to prevent their huge accumulation of stores and weapons falling into German hands, or to send their fleet away to carry on the fight, though its most powerful warships were to be crippled by the Royal Navy in July on Churchill’s orders. By many Germans the Führer, the real architect of all these triumphs, was now elevated to a status little below that of a god, and if the German General Staff did not share this view they certainly felt a new respect for Hitler’s abilities as a strategist. It was not only in England, where emphasis tended, however, to be placed on the failure of his predecessor’s invasion plans in 1804 and his final defeat, that Hitler was compared to Napoleon. So far the German Army had not been eager for an invasion, and the German Navy and Air Force had come close to predicting that it would fail. But now, if Hitler said it was possible, then, however much military habits of thought and training counselled caution, it could almost certainly be done.
In July 1940 planning for the invasion of the British Isles, which had hitherto been left to the initiative of the three services, became the concern of the High Command of the Armed Forces (Oberkommando der Wehrmacht, or OKW), to which all three service chiefs were responsible, and on 2 July Hitler issued a formal directive that staff planning was now to begin. This preliminary warning was followed on 16 July 1940 by the famous
Directive No. 16, Preparations for the Invasion of England,
which became the basic blue-print for the whole operation, now given the name
Sea Lion.
Even in the preamble, however, there was a hint of Hitler’s continuing reluctance for a confrontation with Great Britain on her own soil:
Since England, despite its hopeless military situation, still gives no sign of any readiness to come to terms, I have decided to prepare for invasion of that country and, if necessary, to carry it through…. The aim of this operation will be to eliminate England as a base for carrying on the war against Germany and, should it be required, completely to occupy it.
Hitler’s plan, presumably drafted for him by the OKW staff, accepted the previous findings of the Navy on the need for air supremacy and for protection of the flanks of the invasion corridor against naval attack.
The English air force must be beaten physically and morally to a point that they cannot put up any show of attacking force worth mentioning…. The Straits of Dover must be cut off on both flanks by thickly laid minefields and the Western entrance of the Channel in a line from Alderney to Portland will be blocked as well…. The coastal area on the immediate front will be held under fire by strong coastal artillery to form an artillery screen…. It will be an advantage to pin down English Naval forces, shortly before the operation, in the North Sea, and in the Mediterranean (by the Italians) and an attempt will now be made to cripple naval forces based in England by air and torpedo attacks.
Hitler also came down firmly in favour of the Navy’s final preference for the ‘short sea crossing’ against the Army’s old ‘North-West’ scheme for landing in East Anglia:
The landing will be carried out as a surprise crossing on a broad front from the neighbourhood of Ramsgate to the area of the west of the Isle of Wight; some air force units will play the role of artillery and some naval units will act as engineers…. Preparations for the entire operation must be completed by the middle of August.
With only a month to go, and the invasion clearly ‘on’, the service commanders had more than enough to occupy them, but Hitler kept up the pressure from above with
Directive No. 17,
on 1 August, in which, in his lordly way, he declared:
I have decided to carry on and intensify air and naval warfare against England in order to bring about her final defeat.
For this purpose I am issuing the following orders:
The Directive also declared that ‘I am reserving terror attacks’, i.e. the bombing of cities, ‘as reprisals’ and ordered that ‘intensification of the air war can begin on 5 August 1940’, though the actual date was to be fixed by the air staff according to weather and other conditions.
During the next few weeks Hitler’s Commander-in-Chief, Field Marshal Keitel, and Keitel’s subordinates, General Jodl and Major-General Warlimont, Chief of the Operations Branch, issued a steady stream of orders which can have left the three service commanders in no doubt that the Führer was in earnest. On 5 August Keitel himself signed a somewhat grandiose signal declaring ‘The Great Air Offensive against England will begin within a few days’, and two days later he issued further orders ‘On deceptive measures to maintain the appearance of constant threat of invasion of the United Kingdom’. It was not only in the title of this document that a note of hesitation crept in: