DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "DTD/xhtml1-transitional.dtd">
Dr Andrew Gordon is Reader in Defence Studies, King’s College London, and Maritime Warfare Historian on the Higher Command and Staff Course, Joint Services Command and Staff College, Defence Academy of the UK.
As a maritime historian, my problem with Battle of Britain culture rests on just one specific point: the often stated and always implied claim that ‘nothing stood between Britain and Nazi occupation except Fighter Command.’ This is quite untrue. Among other things, the largest operational fleet in the world stood between. Whatever opinions may be held elsewhere about operation SEALION (the vaunted German invasion), it was the German Navy (Kriegsmarine) that was going to have to sign the chit for a logistical, resources, force-protection and seamanship nightmare, and the more they studied the daunting obstacles facing them, the more anxious they became to be let off the hook.
There was so much wrong with the materiel and methods available for SEALION, that it is difficult to know where to start.
The basic order-of-battle facts are that, having lost ten destroyers in Norway, the Germans now had only ten to protect four beach landing areas. At the beginning of September the Admiralty had disposed sixty-seven (plus six cruisers) for immediate response to an invasion alarm. The first warning of the invasion’s sailing would come, it was hoped, from RAF reconnaissance over the assembly ports. But in case – as was likely – the Germans waited until after dark before commencing their 12-hour toil across to England, the Royal Navy had a pool of 700 armed patrol craft (requisitioned motor yachts and trawlers) of whom around 200 were on picket duty “off the north coast of France” every night. So, owing to either the air reconnaissance or the trip-wire patrols, there was a high likelihood that the German invasion armadas would have found British destroyers between them and their intended landing-beaches when they approached on the morning of D-Day. As well as torpedoes and guns, each destroyer carried 40 depth-charges filled with 600-800lbs of Amatol (depending on Mk) which could have demolished the tows of wallowing barges packed with soldiers and horses.
The second tranche of RN interventions would have been the thirty-four corvettes and sloops, and the MTBs, employed on East Coast and Channel convoy routes. Then, within twenty-four hours of the alert, the cruisers and capital units of the Home Fleet would have started to arrive from the far north and west. 165 minesweepers of varying pedigree were at hand to maintain swept channels. Finally, many of the thirty-five submarines based in home waters would have headed for the Channel to disrupt the shuttling back and forth of barges required by the German build-up for the next ten days.
The RN would have taken casualties – it’s never baulked at that. But to inflict serious losses the Luftwaffe would have had to discover capacities it had yet to demonstrate and yet to train for. Off Norway, the Home Fleet had been bombed for days on end, but only two of its destroyers (out of an inventory of over eighty) were sunk. During Dunkirk, many destroyers were damaged by air attack, and for a while the most valuable ones were withdrawn (in the manner of Fighter Command from France), but none of the four sunk by the Luftwaffe were in open water and free to manoeuvre at speed when fatally attacked. In brief, the war so far had provided no evidence that, in extremis, air-power – German or British – was a naval operations show-stopper. In 1940, the Luftwaffe’s Stukas were specialists in Army close-support, and the anti-shipping skills which they were to display in the Mediterranean in ‘41 (starting with Fliegerkorps X’s attack on Illustrious in January) cannot be retro-fitted to the previous summer.
The ‘Brief Statement of Reasons for Cancellation of Invasion of England’, prepared by the German Naval Historical Staff in 1944, states:
Grand Admiral Raeder (head of the Kriegsmarine in 1940) said much the same, in almost the same words, after the war; and had tried to dodge out of the invasion as early as July 11th. The last sentence quoted above appears to mean that, even if the Luftwaffe had won the air battle of Britain, the Kriegsmarine would still not have wanted to attempt SEALION.
The same Kriegsmarine document acknowledges that “there was an air of relief among leading [naval] personalities when sufficiently solid grounds were found to warrant postponement and finally cancellation.” And it is obvious that in August-September 1940, the best outcome for the Kriegsmarine would be for the invasion to be cancelled and for someone-else to take the blame. Thanks to Fighter Command’s victory over the Luftwaffe, that is what they got – their get out of gaol card. But that is not at all the same thing as there being nobody but the RAF ready, willing and able to defeat Operation SEALION.
Whether the air battle was the cause or the occasion for the cancellation of SEALION is therefore a moot point. Hitler’s order on the 17th September to ‘postpone’ the invasion appears directly consequent on the Luftwaffe’s losses of the 15th, held to be the climactic day of the Battle of Britain. But as Ian Kershaw tells us, “Hitler had never been convinced that the German air offensive would successfully lay the basis for the invasion of which he was in any case so sceptical.” And
between 10 and 13 September there were signs that Hitler had gone utterly cold on the idea of a landing. On 14 September he then told his commanders that the conditions for 'Operation SEALION' had not been attained. The military chiefs themselves did not believe that a landing at that stage could be successfully carried out. 'I had the impression at this discussion,' wrote Nicolaus von Below many years later, 'that Hitler had given up hope of a successful invasion of England the following spring. In autumn 1940 the great unknown, the fairly improvised crossing over the sea, frightened him. He was unsure.' 
No doubt the result of the air battle on the 15th assisted this attack of cold feet –– but so too may have the deployment of the Home Fleet southwards from Scapa Flow to Rosyth on the 13th, bringing the heavy ships eight hours closer to the invasion arena. Further, to launch a laborious and protracted invasion into the equinoctial gales would have been inviting disaster. The German High Command had actually been warned way back in July that “the weather in the North Sea and Channel during the second half of September is very bad and… the main operation would therefore have to be completed by September 15.” The pencilled-in date kept slipping, but by mid-month Hitler’s mind was diverting to the bombing of London and (covertly) to Russia. To borrow a Napoleonism, he was learning that an elephant cannot easily kill a whale.
The first misconception about the summer of 1940 is that German planning was a thing of Teutonic rigour and logic. In fact they had no coherent game-plan for prosecuting the war against Britain after the collapse of France, and it took them some time to realise that the war was not over. Then, Goering boasted that he would bring Britain to heel through a campaign of shock and awe, which would include the destruction of the RAF, making an invasion unnecessary. Partly as a Psy-Ops ploy against British morale, Hitler ordered SEALION to be prepared, but executed only as a last resort and if necessary (which logically meant: if Goering failed to fulfil his boast).
Local air superiority would have sufficed for invasion, but within Goering’s grand scheme was the desideratum that the Luftwaffe somehow achieve air supremacy over England, from airfields in France. Partly because the other German Services were anxious to raise the ‘air’ bar to an improbable height, the invasion project became illogically linked with this sweeping precondition which could most plausibly be attained from airfields in England after an invasion. An obvious parallel is the Allies’ invasion of Sicily in ’43: given the distance from fighter bases in Tunisia and Malta, it would have been daft to make air supremacy over the island a condition for invading. Instead, the Allies exploited air superiority over the landing areas until airfields ashore, from which supremacy could be contested, were up and running. Ditto Normandy.
German leaders were thus unfocused and irrational about the linkages between the air-campaign and a mooted invasion; and they were hopelessly disunited. Goering remained dismissive of SEALION and never bothered to attend a planning meeting, possibly because the project anticipated the Luftwaffe’s failure to defeat Britain single-handedly.
Long before the air battle started, Dowding understood that defence against invasion was going to be a joint business, as his famous letter of 16th May, calling for Fighter Command to be withdrawn from France demonstrates. The conditions he specified were: “…if an adequate fighter force is kept in this country, if the fleet remains in being , and if Home Forces are suitably organised…” This seminal letter is commonly quoted by Battle of Britain celebrants, but the words underlined here by me, and the bit about the Army, never seem to get mentioned.
A most telling piece of evidence, and one whose implications cannot be evaded, is discussed below by Gary Sheffield: the War Cabinet’s despatch in mid-August of an armoured brigade to fight the Italians in North Africa. Given the British Army’s shortage of such assets, this seemingly bizarre decision must have been permitted by one of two possible ‘home defence’ assumptions: either Churchill was already taking for granted a decisive RAF victory in the developing air battle; or he (First Lord of the Admiralty until three months ago) did not really believe that SEALION would get ashore, irrespective of the air battle.
Perceptions of SEALION’s prospects varied between, and within, every Service, British and German, with varying degrees of bias, and none can be validated. In the analysis of Wing Commander H.R.Allen (himself one of The Few):
It was seapower that ruled the day in 1940, and fortunately Britain had a sufficiency. The air situation was, of course, important, but by no means fundamental. Without doubt the five hundred or so section, flight and squadron leaders of Fighter Command earned their laurels. But the real victor was the Royal Navy, the Silent Service… 
In reality, the issues are impossible to separate so categorically. But clearly the Home Fleet, along with Bomber Command, Costal Command, the Army, the weather (worse, that summer, than remembered), Goering’s grandstanding, disunity in the German high command, and the huge practical obstacles facing SEALION all went into the witches’ stew which cursed the project.
In summary, the link between the air battle and the non-event of SEALION is much less direct and exclusive than commonly wished by Battle of Britain celebrants. Certainly, the RAF added daytime command of the air to the indisputable command of the sea which Britain already possessed, but the airspace over southern England did not thereby become the last court of appeal against invasion. None of the above is new; but the sailors have been silent for too long, and popular understanding of the ‘whole-picture’ needs to be adjusted so that credit for strategic effect may be shared (belatedly) where credit is due.
To some extent, there is a parallel with Trafalgar (thank you Private Eye!). Let us suppose that Napoleon had remained intent on invading England. The Channel Fleet under Nelson’s senior, ‘Billy Blue’ Cornwallis, had been blockading the main French fleet in Brest for months, and to it was expected to fall the task of defeating the invasion. To assume (as some still do) that if Nelson’s Mediterranean Fleet had failed to find Villeneuve’s Franco-Spanish fleet, or been beaten by it, the British would soon have been speaking French, is a leap of mythology which vaults over the very existence of the main British naval force. It also makes the security of Britain look a more hand-to-mouth affair than it actually was. In due course the ships of the Channel Fleet dispersed to other duties, their role in deterring Napoleon’s invasion overlooked by popular history. To point out that the public in time of war (like the Press in August) demands simple, iconic images, painted in primary colours, detracts nothing from the bravery of Nelson and his men, or their extraordinary victory off Cadiz.
All that having been said, the air Battle of Britain, and the marvelous rhetoric which Churchill wove around it, very likely saved Britain in a less direct way: by persuading neutral America that we were worth backing. With our engineering industries diverted from exporting to war production, we were fast running out of the gold and dollar reserves with which to buy food and raw materials. Unglamorous as it sounds, balance-of-payments meltdown was the real, if invisible, danger in late 1940, and Churchill’s real gamble. If Congress had not solved Britain’s 'dollar problem' in early ‘41 by passing the Lend-Lease Bill, we would soon have had to make peace or starve. A succession of events - the 'Deliverance of Dunkirk’, the sinking of the French fleet, the 'Battle of Britain', the Blitz, our military support for Greece – combined to tip the scales in favour of Lend-Lease. But of this list, the Battle of Britain presented the most powerful image: the first positive, media-visible, strategic-scale defeat of Hitler’s armed forces. An ambient fleet-in-being victory could not possibly have had such an impact on its own.