SECRET May 16, 1940 Sir, I have the honour to refer to the very serious calls which have recently been made upon the Home Defence Fighter'Units in an attempt to stem the German invasion on the Continent. 2, I hope and believe that our Armies may yet be victorious in France and Belgium, but we have to face the possibility that they may be defeated. 3. In this case I presume that there is no-one who will deny that England should fight on, even though the remainder of the Continent of Europe is dominated by the Germans. 4. For this purpose it is necessary to retain some minimum fighter strength in this country and I must request that the Air Council will inform me what they consider this minimum strength to be, in order that I may make my dispositions accordingly. 5. I would remind the Air Council that the last estimate which they made as to the force necessary to defend this country was 52 Squadrons, and my strength has now been reduced to the equivalent of 36 Squadrons. 6. Once a decision has been reached as to the limit on which the Air Council and the Cabinet are prepared to stake the existence of the country, it should be made clear to the Allied Commanders on the Continent that not a single aeroplane from Fighter Command beyond the limit will be sent across the Channel, no matter how desperate the situation may become. 7. It will, of course, be remembered that the estimate of 52 Squadrons was based on the assumption that the attack would come from the eastwards except in so far as the defences might be outflanked in flight. We have now to face the possibility that attacks may come from Spain or even from the North coast of France. The result is that our line is very much extended at the same time as our resources are reduced. 8. I must point out that within the last few days the equivalent of 10 Squadrons have been sent to France, that the Hurricane Squadrons remaining in this country are seriously depleted, and that the more Squadrons which are sent to France the higher will be the wastage and the more insistent the demands for reinforcements. 9. I must therefore request that as a matter of paramount urgency the Air Ministry will consider and decide what level of strength is to be left to the Fighter Command for the defences of this country, and will assure me that when this level has been reached, not one fighter will be sent across the Channel however urgent and insistent the appeals for help may be. 10. I believe that, if an adequate fighter force is kept in this country, if the fleet remains in being, and if Home Forces are suitably organised to resist invasion, we should be able to carry on the war single handed for some time, if not indefinitely. But, if the Home Defence Force is drained away in desperate attempts to remedy the situation in France, defeat in France will involve the final, complete and irremediable defeat of this country. I have the honour to be, Sir, Your obedient Servant, Air Chief Marshal, Air Officer Commanding-in-Chief, Fighter Command,Royal Air Force. Document-7: Battle of Britain - 1940 / Dowdings Letter
That was a very important memo which contributed greatly to the outcome of the Battle of Britain....most significant in RAF history perhaps...thought to have moderated WSC thinking since the French were requesting more and more Hurricane squadrons,a further 10 being the last request. Dowding could see that if the drain on fighter squadrons were allowed to continue that the British home defence was in danger of being "bled white". The Battle for France from 10 May to 3 June cost the RAF dear with almost a 1000 aircraft lost, 432 were fighters in addition to the ones lost over Dunkirk.Moreover it also took a tranche of experienced pilots to be lost, such by 28 May 1940 the UK pilot establishment was 1268 but the actual strength was down to 932....a deficiency of over 300. On 4 June 1940,Dowding sent the following short note to fighter squadrons that had been engaged in the Battle for France. My dear Fighter Boys. I don't send many congratulatory letters and signals,but I feel that I must take this occasion,when the intensive fighting in Northern France is for the time being over,to tell you how proud I am of you and the way which you have fought since the "Blitzkrieg" started.I wished that I could have spent my time visiting you and hearing your accounts of the fighting,but I have occupied myself in working for you in other ways.I want you to know that my thoughts are always with you and that is you and your fighting spirit which will crack the German Air Force,and preserve our Country through the trials which yet lie ahead. Good luck to you. (Dowding resisted any planning that Spitfires should be sent to France as an element of the BEF.) Per Ardua Ad Astra