On 16 July 1940, following Germany's swift and successful occupation of France and the Low Countries and growing impatient with Britain's outright rejection of his recent peace overtures, Hitler issued
Führer Directive No. 16, setting in motion preparations for a landing in Britain. He prefaced the order by stating: "As England, in spite of her hopeless military situation, still shows no signs of willingness to come to terms, I have decided to prepare, and if necessary to carry out, a landing operation against her. The aim of this operation is to eliminate the English Motherland as a base from which the war against Germany can be continued, and, if necessary, to occupy the country completely."
[7]
Hitler's directive set four conditions for the invasion to occur:
[8]
- The RAF was to be "beaten down in its morale and in fact, that it can no longer display any appreciable aggressive force in opposition to the German crossing".
- The English Channel was to be swept of British mines at the crossing points, and the Strait of Dover must be blocked at both ends by German mines.
- The coastal zone between occupied France and England must be dominated by heavy artillery.
- The Royal Navy must be sufficiently engaged in the North Sea and the Mediterranean so that it could not intervene in the crossing. British home squadrons must be damaged or destroyed by air and torpedo attacks.
This ultimately placed responsibility for Sea Lion 's success squarely on the shoulders of Raeder and Göring, neither of whom had the slightest enthusiasm for the venture and, in fact, did little to hide their opposition to it.
[9] Nor did Directive 16 provide for a combined operational headquarters under which all three service branches (Army, Navy, Air Force) could work together under a single umbrella organisation to plan, coordinate and execute such a complex undertaking (similar to the Allies' creation of the
Supreme Headquarters Allied Expeditionary Force (SHAEF) for the later Normandy landings).
[10]
...
In 1940 the German Navy was ill-prepared for mounting an amphibious assault the size of Operation Sea Lion. Lacking purpose-built landing craft and both doctrinal and practical experience with amphibious warfare, the
Kriegsmarine was largely starting from scratch. Some efforts had been made during the inter-war years to investigate landing military forces by sea, but inadequate funding severely limited any useful progress
...
Given barely two months to assemble a large seagoing invasion fleet, the
Kriegsmarine opted to convert inland river barges into makeshift landing craft. Approximately 2,400 barges were collected from throughout Europe (860 from Germany, 1,200 from the Netherlands and Belgium and 350 from France). Of these, only about 800 were powered (some insufficiently); the rest had to be towed by tugs.
...
Cancellation
Both the British and the Americans believed during the summer of 1940 that a German invasion was imminent, and studied the forthcoming
high tides of 5–9 August, 2–7 September, 1–6 October, and 30 October-4 November as likely dates.
[67] The Germans were confident enough to film it in advance. A crew turned up at the Belgian port of
Antwerp in early September 1940. For two days they filmed tanks and troops landing from barges on a nearby beach under simulated fire. It was explained that as the invasion would happen at night, Hitler wanted the German people to see all the details.
[68]
On 17 September 1940, however, Hitler held a meeting with
Reichsmarschall Hermann Göring and
Generalfeldmarschall Gerd von Rundstedt during which he became convinced the operation was not viable. Control of the skies was still lacking, and coordination among three branches of the armed forces was out of the question. Later that day, Hitler ordered the postponement of the operation. He ordered the dispersal of the invasion fleet in order to avert further damage by British air and naval attacks.
[69]
...
After the
London Blitz, Hitler turned his attention to the
Soviet Union, and
Seelöwe lapsed, never to be resumed.
...
The great majority of military historians believe Operation Sea Lion had little chance of success.
...
Reichsmarschall Hermann Göring,
Commander-in-Chief of the
Luftwaffe, believed the invasion could not succeed and doubted whether the German air force would be able to win control of the skies; nevertheless he hoped that an early victory in the Battle of Britain would force the UK government to negotiate, without any need for an invasion.
[75] Adolf Galland, commander of
Luftwaffe fighters at the time, claimed invasion plans were not serious and that there was a palpable sense of relief in the
Wehrmacht when it was finally called off.
Generalfeldmarschall Gerd von Rundstedt also took this view and thought that Hitler never seriously intended to invade Britain and the whole thing was a bluff to put pressure on the British government to come to terms following the
Fall of France.
[76] He observed that
Napoleon had failed to invade and the difficulties that confounded him did not appear to have been solved by the Sea Lion planners. In fact, in November 1939, the German naval staff produced a study on the possibility of an invasion of Britain and concluded that it required two preconditions, air and naval superiority, neither of which Germany ever had.
[77] Grand Admiral
Karl Dönitz believed air superiority was not enough and admitted, "We possessed neither control of the air or the sea; nor were we in any position to gain it."
[78] Grand Admiral
Erich Raeder thought it would be impossible for Germany to successfully invade the UK; he instead called for
Malta and the
Suez Canal to be overrun so German forces could link up with Japanese forces in the
Indian Ocean to bring about the collapse of the
British Empire in the Far East, and prevent the Americans from being able to use British bases if the United States entered the war.
[79]
As early as 14 August 1940, Hitler had told his generals that he would not attempt to invade Britain if the task seemed too dangerous, before adding that there were other ways of defeating the UK than invading
