SEALION

SEALION (German, Seelöwe)was the German codename for the invasion of England. On 13 July 1940 the question of greatest concern to Hitler was why Britain was still unwilling to make peace. Halder, chief of the Army General Staff, noted in his diary: ‘He believes, as we do, that the answer to this question is that Britain is still placing her hopes in Russia. He therefore expects that it will be necessary to force the UK to make peace.’

Three days later, on 16 July, Hitler issued Directive No. 16 ‘on preparations for a landing operation against England’. As the first prerequisite for it he mentioned that the British Air Force must be eliminated to the point that it would not have the strength necessary to mount a significant attack on a German attempt to cross the Channel. In conferences with the commanders-in-chief of the Wehrmacht services on 21 July, Hitler repeated his doubts about a landing operation: ‘If it is not certain that preparations can be concluded by the beginning of September, other plans will have to be considered.’ Among these plans was an attack on the USSR.

Above all, the navy voiced serious doubts about the feasibility of a landing. The importance of air supremacy was increasingly emphasized, not only for the crossing but also for the orderly deployment of the transport fleet and the necessary minesweeping operations. On 11 July Raeder, C-in-C of the navy, explained to Hitler that a landing could only be a ‘last resort’. He demanded strong air attacks, for example on Liverpool, ‘to make the entire nation feel the effects’. After Raeder had informed him on 31 July that the navy's preparations for a landing could not be concluded before 15 September, Hitler decided that all preparations should take that date as a deadline, but his final decision would depend on victory in the battle of Britain. Eight or, at most, fourteen days after the start of the ‘great air campaign against Britain’, which could begin at any time from about 5 August, he intended to decide whether or not SEALION could take place in 1940.

After the fall of France the Luftwaffe was in a very favourable geographical position for operations against England, but it did not have any overall tactical plan. In spite of Hitler's orders to prepare an invasion, his hesitation about carrying it out greatly complicated the problem of setting consistent priorities and goals in an air war against that country. However, there was general agreement that domination of the air, or at least regional air supremacy, was essential for a landing as well as for an independent strategic air war against the UK.

Preparations for the invasion, which was to be carried out by divisions drawn from Army Group A's Ninth and Sixteenth Armies (see Map 95), included the recording of all available sea and river craft in Germany and the occupied countries, embarkation and disembarkation exercises, and the formation of occupation authorities which planned, among other tasks, the arrest of certain prominent citizens (see Black Book).

When the battle for air supremacy over England began by 13 August 1940, Göring'sAdlertag (Eagle Day), seven weeks had passed since the fall of France, during which time the British had been able further to improve their air defences. Thus the battle of Britain took the form of a strategically and tactically improvised air offensive against an air defence system which the British had been building up systematically for four years.

On 14 September 1940 Hitler informed the Cs-in-C that the navy had completed preparations for SEALION, but in spite of the ‘enormous’ successes of the Luftwaffe the preconditions for the operation did not yet exist. Although domination of the air had not been achieved, Hitler did not want to cancel SEALION as yet because that would destroy the effect of the air attacks on British morale. Whereas earlier the purpose of the air war had been to create the preconditions for a landing, Hitler now evidently viewed the landing preparations as a psychological instrument to support the air war, which had been indecisive but might still lead to victory.

Raeder suggested 8 October as the next date for a landing, as the situation in the air would not change before the next favourable invasion dates, 24– 27 September. His remark that a Channel crossing would not be necessary if the Luftwaffe, had been completely successful by then and his demand for air attacks ‘without regard to SEALION’, suggests that by this time he had ruled out a landing in 1940. Hitler, however, ordered preparations to be made for 27 September and named 17 September as the date for confirmation or otherwise. Only after that should 8 October be considered. The main thing was, however, that the air attacks should be continued without interruption.

Göring's remark on 16 September that SEALION must not disturb the operations of the Luftwaffe and his reference to ‘subsequent attacks spread all over Britain’ show that he, like Raeder, no longer expected the landing operation to be carried out. In view of the first dispersal order of the Wehrmacht High Command of 19 September for the SEALION transport fleet to avoid further losses as a result of British air attacks, and the instructions to halt further deployment of the transport ships, any serious preparations by the Luftwaffe for the invasion had become superfluous.

In fact war-economy considerations forced a disbanding of the deployment for SEALION. Because of the losses caused by British air attacks, on 2 October Hitler ordered that all measures taken in conjunction with SEALION were to be ‘largely dismantled’. In his Directive No. 18 of 21 November he again stated that changes in the general situation might make it possible, or necessary, to revert to the plan in the spring of 1941; but he evidently expressed himself more plainly on 5 December, when Halder noted: ‘SEALION can be left out of account.’

On 18 December 1940 Hitler issued Directive No. 21 in which he ordered the Wehrmacht to be prepared to ‘crush Soviet Russia in a rapid campaign’, codenamed BARBAROSSA, even before the UK had been defeated. In this way Hitler attempted to correct the priority of the two fronts, deriving from his basic aim of conquering Lebensraum (living-space) in the east.

Klaus A. Maier

Bibliography

Schenk, P. , Invasion of England 1940 (London, 1990).