Operation Sealion: The
Planned German Invasion ofBritain
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Operation Sealion was the name
given by Hitler for the planned invasion of Great Britain in 1940.
Thankfully it was never carried
out as the Germans lost the Battle of Britain and Hitler was more interested in the forthcoming
attack on Russia as opposed to invading Britain.
The projected invasion on Britain included:
6 divisions invading Kent via
the areas near Ramsgate, Folkstone and Bexhill.
4 divisions invading Sussex and
Hampshire via the area around Brighton and the Isle of Wight and 3 divisions invading Dorset via
From Kent they would advance to
south-east London and then to Malden and St. Albans north of London.
From Sussex/Hampshire, they
would advance to the west of London and meet up with the other 6 divisions thus encircling London.
Other parts of the group would head towards Gloucester and the River Severn
The whole plan relied on Germany
having complete control of the English Channel, which, in turn meant that Germany had to have
control of the skies so that the Royal Air Force could not attack German ships crossing the
Channel. Hence victory in the Battle of Britain was an integral part of the plan.
Operation Sealion looked simple
in theory. Britain should have been an easy target. The Luftwaffe was very experienced in modern
warfare, the Wehrmacht had experienced astonishing success since the attack on Poland and the
British had lost a vast amount of military hardware on the beaches of Dunkirk.
It is said that Hitler was
prepared to offer Britain generous peace terms. However, on May 21st, 1940, Admiral Raeder told
Hitler about a plan to invade Britain and Hitler, it is said, was taken in by the plan. If Britain
had not surrendered, Hitler had planned an economic war which could have taken a long time to be
effective. However, a military conquest of Britain would be swift and decisive. The military
success of the German military since September 1939, seemed to confirm in Hitler’s mind that an
attack on a demoralised British Army would be swift.
Towards the end of June 1940,
Hitler gave the order for the German military to make plans for an invasion of
The German Navy detailed many
problems that would be experienced for either a short or a long crossing.
In December 1939, the Wehrmacht
had produced its own report. This favoured a surprise attack on Britain via East Anglia by 16 or 17
It was only when it became clear
that Britain would not sign peace terms that Hitler gave his backing to an invasion. On July 2nd
1940, Hitler gave his first tentative orders regarding a possible invasion of Britain. It stated
"a landing in England is
possible, providing that air superiority can be attained and certain other necessary conditions
fulfilled.....all the preparations must be made on the basis that the invasion is still only a
plan, and has not yet been decided upon." Hitler, July 2nd 1940.
Around this time the Auxiliary
Units were being formed in Whitehall.
On July 13th, the German army
chiefs presented their plan to Hitler. They were so confident of success that they believed that
Britain would be occupied within a month.
Hitler wanted Sea Lion to be
over by mid-September.
One of the interesting issues to
come out of this episode was the inability of the three units that made up the German military to
either work together or support one another. Another key point that came out of this episode in the
war, was Hitler's seeming refusal to listen to his military commanders and wanting things done his
way. This came out of the success the military had against Poland and the nations of Western Europe
- countries attacked without the overwhelming support of the military but attacked because Hitler
instinctively knew that they would win - or so he believed.
OPERATION SEALIONBy CART member Peter
D Antill BA (Hons). MSc (Econ). PGCE (PCE).
See Peter's other article on Small Arms and Support Weapons of the Wehrmacht here.
A Primer and List of Sources (Bottom of
Author's Note: This article is designed
only as a short introduction to the topic of Operation Sealion. At some stage, the author intends to write a
much more detailed series of articles about this plan, as well as the plans for British defence against such
an invasion and the plans for resistance in the event of occupation.
This year marks the 70th anniversary of the
Battle of Britain, the gallant struggle of the RAF's Fighter Command against the might of the
GermanLuftwaffe.(1) While a major campaign in itself and
the subject of numerous books, articles, webpages and even a major motion picture, this attempt by the
Luftwaffe to attain air superiority over Great Britain by defeating the RAF, which became known as the Battle
of Britain, was in fact fought as the main prerequisite for the planned German invasion of Britain, codenamed
Operation SEALION and originally scheduled for September 1940. The evacuation of the BEF from Dunkirk had
left theWehrmacht in control of the Channel Coast
after the fall of France and while this was an enviable position to be in, it meant that the Germans were now
forced to contemplate what to do about what the Chief of Luftwaffe Intelligence called 'the most dangerous
enemy'. The dire state of the British Army after the evacuation from the continent demanded immediate
attention and while it would take time for reorganise and re-equip the ground forces available; they could
only get stronger as time went on. Arguments still rage to this day as to how serious Hitler actually was, in
contemplating an amphibious invasion ofBritain, but whatever the case, the preparations that were made were conducted in a serious manner
and involved a considerable cost to the German war effort. Whatever their actual chances of success, the
landings were planned as a contingency and were dependent on the efforts of theLuftwaffe to achieve air superiority over the landing area and much of
southernBritain, in order to
forestall both the RAF and Royal Navy intervening in the operation.
OKW (Oberkommando der Wehrmacht or High Command of the Armed Forces) was the main strategy-making body and was headed
by Hitler, with Generals Keitel and Jodl alongside. To this reported the high commands of the various
services, the OKH (Oberkommando
des Heeres - Army High Command underGeneralfeldmarschall von Brauchitsch), OKM (Oberkommando der Marine - Naval High Command
underGrossadmiral Raeder) and OKL (Oberkommando der Luftwaffe - Air Force High Command underReichsmarschall Göring) – see above. The timeline of events relating to Sealion is as
·Up until November 1939 – No serious consideration was given by Hitler
or the German OKW to an invasion of theBritish
Isles. The main focus of any operations would be an air and naval
blockade to 'encourage' negotiations.
·November 1939 – Both OKM and OKH conduct separate studies as to the
feasibility of an amphibious landing.
·January 1940 –Grossadmiral Erich Raeder responds to the OKH study (codenamedNorth West) by
pointing out the many difficulties and obstacles to such an operation. Both Raeder and Hitler still prefer the
option of an air and naval blockade.
·21 May 1940 – Raeder quizzes Hitler as to the possibility of an
amphibious landing and receives a negative response. Despite this, OKM continues to study the problem and
recommends a cross-channel route rather than aNorth
·10 July 1940 – Battle of Britain
·16 July 1940 – Hitler issues Fuhrer Directive No. 16. This states "I
have decided to prepare a landing operation againstEngland, and if necessary, to carry it out. The aim of this
operation will be to eliminate the English homeland as a base for the prosecution of the war
againstGermany" and makes it clear
that theHeer plan will form the basis for moving
·20 July 1940 – OKH publishes its 'broad front' plan, detailing a
landing across a 237-mile front from the Thames Estuary toLymeBay. Raeder rejects
it as the Navy lack the resources to support a lift of that magnitude.
·21 August 1940 – OKH submit a scaled down plan that details a landing
by ten divisions over four days between Ramsgate andBrighton (100 miles). Raeder amends this plan further
to a landing of nine divisions over four days across a front of ninety miles. The lead elements from Strauss' 9th
Army and Busch's 16th Army would come ashore between Folkestone andBrighton, supported by the 7thFlieger and 22ndLuftlande Divisions, as well as 250 amphibious
·Mid-September 1940 – TheKriegsmarine finishes assembling the shipping to be used in the
·26 – 27 September 1940 – Most likely landing dates given
theHeer's demand for dawn landings on an ebbing tide
and the Navy's requirement for partial moonlight during transit.
The main planning for the operation came out
of two directives from Hitler and a supplemental one from the OKW, the first of which was issued on 16 July
1940. As mentioned above, up to this point, various meetings had occurred and planning documents had been
issued by all three services and their High Commands, including a memo from Jodl dated 12 July 1940 which
alluded to the operation being calledLöwe (Lion) and being a broad front
operation, not much more complex than an extended river crossing. While the Heer found the idea appealing,
rivers are not tidal, are not subject to severe weather and don't have the enemy's Home Fleet in a position
to contest the crossing. Following this was a meeting between Hitler, von Brauchitsch,
Artillerie Franz Halder (the Army Chief of Staff) on 13 July
1940, where Halder presented more detailed planning proposals that outlined an operation incorporating 39
divisions and around 500,000 men (published 20 July). Hitler authorised continued preparations but was
puzzled over the lack of peace feelers from Britain, as he once again outlined that he would prefer a
negotiated settlement as he did not wish to hand Britain a military defeat which would disrupt the empire and
only be of benefit to Japan and the USA. Hitler also reviewed his decision to reduce the size of the army by
thirty-five divisions to release additional manpower for the economy and scaled it down to a reduction of
Fuhrer Directive No. 16 issued on 16 July
1940 stated that theWehrmacht would 'begin preparations for, and
if necessary carry out, an invasion ofEngland. The aim of this operation is to eliminateGreat
Britain as a base of operations from which the war
againstGermany can be
fought and, if necessary, the island will be completely occupied.' An invasion would be carried out on a
broad front and preparations completed by mid-August. TheLuftwaffe would eliminate the RAF as an effective fighting force and interdict the Royal Navy
should it try to intervene and theKriegsmarine would furnish an invasion fleet
and protect it. Current army plans would form the basis of the operation, although the line would be
shortened slightly to between Ramsgate and theIsle of
Wight. Hitler also confirmed that the operation would be
codenamedSeelöwe (Sealion). In some ways, it seemed that theLuftwaffe was expected to almost defeatBritain by itself. Goring and his commanders
however, mostly ignored the directive and continued with their own plans - they thought an invasion was going
to be unnecessary anyway, while Raeder and theKriegsmarine thought that OKW was insane. From this point, theHeer continued to be the main supporter of the plan, with the Luftwaffe lukewarm to the
idea and theKriegsmarine trying to torpedo
Following Fuhrer Directive No. 16, in which
many historians highlight the words 'and if necessary carry out, an
invasion' as an indication of Hitler's lack of commitment, the
second half of July was filled with various staff meetings and proposals where the Luftwaffe confirmed it
would be able to start a major air campaign against the RAF in early August but theKriegsmarine would not be able to complete its preparations until mid-September. On 28 July 1940,
they proposed that if the invasion were to go ahead that a beachhead be established
nearDover, the closest point
to the continent, where a narrow corridor could be protected by minefields to each side as well as groups of
U-Boats and E-Boats beyond these. TheKriegsmarine estimated it would take ten days
to put the first wave ashore and needless to say, theHeer was horrified. It had wanted landings all along the south coast from Folkestone to
Brighton with a separate landing fromCherbourg. It also wanted wheeled and tracked vehicles and so all the car ferries were to be used
along with all the cross-channel tourist facilities. The first wave was to be landed over three to four days
and consist of 260,000 men, 30,000 vehicles and 60,000 horses. This was followed by a memo dated 31 July
1940, which advised that given theKriegsmarine's preparations were complete by
15 September 1940, the dates most suitable for invasion would be from 22 - 26 September, when the weather was
often bad. It could not however, guarantee to able to protect the invasion from the Royal Navy and would not
be able to guarantee resupply if there was indeed bad weather. It was suggested that the invasion was put off
until May 1941 when additional surface assets would be available and additional work be able to be carried
out on converting or building vessels to allow for amphibious operations.
Fuhrer Directive No. 17 was issued on 1
August 1940 (followed by one from OKW) and ordered the intensification of the air campaign against the RAF,
targeting their air units, ground installations, observation facilities and aircraft factories. It also
stated that all preparations for invasion would be completed by 15 September 1940, the original deadline
being kept as Hitler was concerned over the strength of the British Army if the invasion was postponed until
the following spring. Despite misgivings, theKriegsmarine continued to scour the waterways
of occupied Europe for suitable craft, both powered and unpowered and proceeded to convert many of them by
adding drop-down ramps, while theHeer conducted energetic landing exercises,
with propaganda film crews in attendance. Mid-September saw theKriegsmarine complete its assembly of the vessels to be used in the initial lift, as well as the
finalisation of the German forces to be used, the assault routes to be taken, as well as the plans for
Needless to say, theLuftwaffe’s defeat in the Battle of Britain
forced Hitler to postpone the invasion on 17 September 1940 and then on 12 October 1940 postpone it until the
following year. In any case, by then, Hitler’s attention had moved eastwards and was focused on his main
ideological opponent, theUSSR,
with planning and preparations being undertaken for Operation Barbarossa.
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BBC2, Presenter: Dan Cruikshank. Three episodes aired between 28/10/2001 and
It Happened Here (1964), Directors: Kevin Brownlow / Andrew Mollo, 97mins, English/German,
B&W,ASIN: B000CBOZWG, Studio: Film First.
The Real Dad's Army (2009), Channel 4, Part One: 10/01/09, 60mins; Part Two: 17/01/09, 60mins; Part Three:
24/01/09, 60mins. Note: There was another series entitledThe Real Dad's Army, the fourth episode of which was hosted by Ian Lavender and was about the Auxiliary
When Hitler Invaded
Britain, ITV1, 04 July 2004, 22.15 – 23.45, 90