I reiterated to Hitler my viewpoint that an invasion of England could be considered only as a last resort, in order to bring England to negotiate for peace. To achieve this last resort I told him that in my opinion the most effective weapon was a stepped-up, effective U-boat campaign, and the next most effective means would be air attacks on convoys and other important targets, such as the port of Liverpool. In contrast to the Norwegian Campaign, I could not recommend a landing in England. Aside from absolute mastery in the air, one further requisite was a dependable, absolutely mine-free zone for the troop transports. It was impossible to say how long the creation of such a mine-free channel would take, even if it could be done, or how it could then be kept free from the menace of fresh mines dropped by enemy planes. Furthermore, the flanks of the whole transport area would have to be protected by strong and effective minefields laid by ourselves.
Lastly I called attention to the face that the job of converting and readying ordinary shipping for troop transports and supply ships would be a long and tedious job, and would cause a serious stoppage in the ordinary waterborne traffic of Germany on which both our armament program and domestic economy depended. To go ahead with any real preparations before a definite decision had been made for the landing would be completely wrong. Hitler agreed. He stated that not only was mastery of the air and absolute prerequisite, but the build-up of the submarine arm was also essential.
The Kreigsmarine assess it has to assemble:
All the steamers, barges, lighters, tugs and even motorboats and fishing craft operating on Germany's inland waters as well as out of the seaports themselves. These would additionally need converting to transport troops.
30,000 mines, depth charges, and other material for sealing off the amphibious area.
Mount several heavy coastal batteries at Cape Griz-Nez and other points on the French coast opposite Dover.
I took the matter directly to Hitler, and requested his personal decision as to whether the invasion was to take place on the broad front envisioned by the Army or on the narrow front advocated by the Navy. I pointed out again my opinion that Operation Sea Lion should be regarded only as a last resort in case England could not be forced to negotiate for peace by any other means. Hitler agreed, but wanted to speak again with the Commander in Chief of the Army, as the breadth of the invasion front might be a decisive factor in the whole ensuing land campaign. At this time the strength of the military forces in England was estimated to be in excess of a million and a half men. Of these 300,000 were seasoned English, French and Canadian troops rescued from Dunkirk and some 150,000 retrieved from other continental Channel ports. They had been rearmed. The would defend the island. The opposing views of the Army and Navy as to the breadth of the landing front were reconciled temporarily by a compromise proposal for the Supreme Command of Armed Forces. Then Hitler made the final decision that the army had to arrange its operations in accordance with what the Navy believed its own forces could achieve. It was still an open question as to whether the Air Force would actually succeed in attaining complete mastery of the air. At the end of August, according to the reports of the Air Force, the prospects seemed very good. In reality, however, the German Air Force had attained no significant superiority over the Royal Air Force, and although some weakening of the enemy's defences was apparent, the British fighters, bombers, and, most important, minelaying planes, were still everywhere in the sky. Our own anti-aircraft defence was not good enough to prevent continuous enemy air activity over the Channel ports, with the result that our congregating shipping and our embarkation areas were under steady observation and attack. On 13 September alone we lost 80 transport barges to enemy air attacks.
Photos of Kiel and Emden show 40-50 merchant ships at Kiel and 350 large motor launches at Emden.
The committee agrees that this was a "new and unusual feature". Both concentrations might have significance; but the merchant ships at Kiel were possibly held up there by "suspected mining or other temporary restrictions", while the 350 possible invasion-craft at Emden "some simple explanation in connection with canal or other water traffic may be the reason.
- Ostend (50 since 31 August)
- Terneuzen (140 since 16 August)
- South end of the Beveland Canal (90 since 1 September)
Ghent is important for (a) iron and steel; (b) textiles; (c) oil fuel storage. Probably barges are going south … to fetch these valuable products. … But movements preliminary to invasion are not impossible. The increase in barges at Ostend is abnormal, but might be accounted for by the removal of obstructions in the canal system.
There is little evidence other than the movement of small craft towards the Channel ports to show that preparations for invasion of the U.K. are more advanced than they have been for some time. … If there is an intention to invade the expedition is [probably] being held in readiness in the Baltic or Hamburg.
An operation in October is not ruled out but unlikely.
At a Luftwaffe conference a report titled "Air Situation, September 15" is presented that states on the 15th they had mounted over 1,000 sorties with 56 aircraft lost. They were forced to concluded that Fighter Command had adequate reserves of aircraft.
Raeder is concerned that invasion barges are being sunk by R.A.F. bombers, recently over 80 were sunk in one night. He suggests: "The present air situation does not provide the conditions for carrying out the operation, as the risk is still too great. A decision should be left over until October."
The German War Diary records: "The enemy air force is still by no means defeated; on the contrary it shows increasing activity. … The Fuhrer therefore decides to postpone Sealion indefinitely."
Two days later a directive is given to scale down preparations and barges are moved back from the Channel ports.
Even Hitler admitted that the invasion could not be made at this time, and therefore would have to be postponed. However, because of the psychological effect on the English public, the decision for the postponement was not to be made public, and the threat of a landing, plus the air attacks on London was to be kept up for its over-all effect.
I had to agree with the reasons Hitler gave, but the most satisfactory thing for me was that, with the landings postponed, the probability was that they would never be carried out. So outwardly all preparations were to be continued until 12 October, when Hitler privately me informed us that the preparations were to be carried out throughout the winter, but only to keep military and political pressure on England. If the movement was to be revived the following year, he said, he would give the necessary orders. To my mind this definitely buried any project for the invasion of England. From the first the Naval War Staff had never budged from its standpoint that an invasion across the Channel was so risky that it should be considered only as the ultimate operation in case all other measures against England Failed.