Operation Sealion

Operation Sea Lion Part of Western Front of World War II Operational scope Normandy, the Belgian coast line, the English Channel and the English coast line from Kent to Dorset, Isle of Wight and parts of Devon, but principally in Sussex and Kent. Planned September 1940 Planned by OKW Objective Elimination of the English home country as a base of operations[1] Outcome cancelled

v • d • e Western Front Prelude 1939 Phoney War - Saar - The Heligoland Bight - Defence of the Reich in 1939 1940 Luxembourg - The Netherlands - (The Hague - Rotterdam - Zeeland - Rotterdam Blitz) - Belgium - (Fort Eben-Emael - Hannut) - France - (Sedan - Arras - Lille - Calais - Paula - Dunkirk - Dunkirk evacuation - Italian Invasion of France) - Britain - Sealion 1941-1943 The Blitz - Cerberus - St Nazaire Raid - Dieppe Raid - Defense of the Reich in 1942 - 1943 1944-1945 Overlord - Dragoon - Siegfried Line - Market Garden - (Arnhem) - Hürtgen Forest - Aintree - Aachen - Scheldt - Bulge - Nordwind - Colmar Pocket - Invasion of Germany - Defense of the Reich 1944 - 1945

Operation Sea Lion (German: Unternehmen Seelöwe) was Nazi Germany's plan to invade England during World War II, beginning in 1940. However, to have any chance of success, the operation required air supremacy over the English Channel. With the German defeat in the Battle of Britain, Sealion was postponed indefinitely on 17 September 1940 and never carried out.^[2]

Background

Following swift victory in the Battle of France, Germany believed the war in the west was won. However, the United Kingdom refused peace talks. As a result, more direct measures to break British resistance were considered.

Grand Admiral (Großadmiral) Erich Raeder of the German Navy (Kriegsmarine) oversaw numerous studies for a German naval assault across the English Channel. The earliest of these, made around November 1939, identified the conditions for invasion:^{[citation needed]}

• The Royal Navy had to be eliminated.
• The Royal Air Force (RAF) air strength had to be eliminated.
• British coastal defences had to be destroyed.
• British submarine action against landing forces had to be prevented.

The German Army High Command (Oberkommando des Heeres, or OKH) originally planned an invasion on a vast scale, extending from Dorset to Kent. This was far in excess of what their navy could supply, and final plans were more modest, calling for nine divisions to make an amphibious landing with around 67,000 men in the first echelon and an airborne division to support them.^[3] The chosen invasion sites ran from Rottingdean in the west to Hythe in the east.

The battle plan called for German forces to be launched from Cherbourg to Lyme Regis, Le Havre to Ventnor and Brighton, Boulogne to Eastbourne, Calais to Folkestone, and Dunkirk and Ostend to Ramsgate. German paratroopers would land near Brighton and Dover. Once the coast was secured, they would push north, taking Gloucester and encircling London.^[4] There is reason to believe that the Germans would not attempt to assault the city but besiege and bombard it.^[5] German forces would secure England up to the 52nd parallel (approximately as far north as Northampton), anticipating that the rest of the United Kingdom would then surrender.

Adolf Hitler's initial warning order on 16 July 1940 reflected the most current thinking and set out the revised minimum pre-conditions. He prefaced his order by stating, "I have decided to prepare a landing operation against England and, if necessary, to carry it out".^[6]

Hitler's conditions for invasion were:

• 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 Straits 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 placed responsibility for Sealion's success on the shoulders of Naval High Command (Oberkommando der Marine or OKM) Grand Admiral (Großadmiral) Erich Raeder and Air Force High Command (Oberkommando der Luftwaffe or OKL) Imperial Marshal (Reichsmarschall) Hermann Göring.

Italian dictator Benito Mussolini offered troops, but Hitler declined.^[7] However, the Italian Air Corps (Corpo Aereo Italiano or CAI) did participate towards the end of the Battle of Britain.

Operation Eagle and air superiority

The aerial battles which resulted from Unternehmen Adler (Operation Eagle Attack) later became known as the Battle of Britain. Adler's objective was for the Luftwaffe to achieve air superiority over the Royal Air Force and allow the German invasion fleet to cross the English Channel. However, the change in emphasis of the bombing from RAF bases to bombing London turned Adler into a strategic bombing operation. This switch afforded the RAF, reeling from Luftwaffe attacks on its bases, time to pull back and regroup.

Navy

The main difficulty for Germany was the small size of its navy. The Kriegsmarine had lost a sizable portion of its large modern surface units in the Norwegian Campaign, either as complete losses or due to battle damage. In particular, the loss of a large portion of their destroyers was crippling. The U-boats, the most powerful arm of the Kriegsmarine, were not suitable for operations in the relatively shallow and restricted English Channel. Although the Royal Navy could not bring to bear the whole of its naval superiority against the Kriegsmarine (most of the fleet was engaged in the Atlantic and Mediterranean), the British Home Fleet still had a very large advantage in numbers. British ships were still vulnerable to enemy air attack, as demonstrated during the Dunkirk evacuation and by the later Japanese sinking of Prince of Wales and Repulse. However, the 22 miles (35 km) width of the English Channel and the overall disparity between the British and German naval forces made the amphibious invasion plan risky, regardless of the outcome in the air. In addition, the Kriegsmarine had allocated its few remaining larger and modern ships to diversionary operations in the North Sea.

Barges assembled for the invasion at the German port of Wilhelmshaven

The French fleet, one of the most powerful and modern in the world, might have tipped the balance against Britain. However, the preemptive destruction of the French fleet by the British by an attack on Mers-el-Kébir and the scuttling of the French fleet in Toulon two years later ensured that this could not happen.

Even if the Royal Navy had been neutralised, the chances of a successful amphibious invasion across the channel were remote. The Germans had no specialised landing craft, and had to rely primarily on river barges. This would have limited the quantity of artillery and tanks transported and restricted operations to times of good weather. The barges were not designed for use in open sea and even in almost perfect conditions, their progress would have been slow and the craft vulnerable to attack. There were not enough barges to transport the first invasion wave nor the following waves with their equipment. Without specialized landing craft, the Germans would have needed to immediately capture a port, an unlikely circumstance considering the strength of the British coastal defences around the south-eastern harbours at that time. The British also had several contingency plans, including the use of poison gas.

Cancellation

On 17 September 1940, Hitler held a meeting with Reichsmarschall Hermann Göring and Field Marshal Gerd von Rundstedt. Hitler became convinced that the operation was not viable. Control of the skies was 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.

It was only a postponement at that stage. Prototypes of two designs of prefabricated jetty, similar in function to later Allied Mulberry Harbours, were built and successfully overwintered in the North Sea in 1941/42.^[8] After cancellation, they were installed on the island of Alderney,^[8] where they remained until being demolished in 1978.

The postponement coincided with a rumour that there had been an attempt to land on British shores at Shingle Street, but it had been repulsed with large German casualties. This was reported in the American press, and in William L. Shirer's Berlin Diary but was officially denied. British papers, declassified in 1993, have suggested this was a successful example of British black propaganda to bolster morale in Britain, America and occupied Europe.^[9]

After the London Blitz, Hitler turned his attention to the Soviet Union, and Seelöwe lapsed, never to be resumed. However, not until 13 February 1942, after the invasion of Russia, were forces earmarked for the operation released to other duties.^[10]

Chances of success

Drill involving an amphibious tank meant for Sealion

Military historians are divided on whether Operation Sealion could have succeeded; some such as Michael Burleigh, and Andrew Mollo believe it was possible. Kenneth Macksey asserts it would have only been possible if the Royal Navy had refrained from large scale intervention^[11] and the Germans had assaulted in July 1940 (they were unprepared at that time),^[12] while others such as Peter Fleming, Derek Robinson and Stephen Bungay believe the operation would have most likely resulted in a disaster for the Germans. 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.

There were a number of errors in German intelligence, and whilst some of these might not have caused problems, there were others (such as the inclusion of bridges that no longer existed^[13] or mis-understanding the usefulness of minor British roads)^[14] that would have been detrimental to German operations, and would have only added to the confusion caused by the layout of Britain's cities and the removal of road signs.^[15]

Post-war test of the plan

In wargames conducted at the Royal Military Academy Sandhurst in 1974, which assumed the Luftwaffe had not yet won air supremacy, the Germans were able to establish a beachhead in England by using a minefield screen in the English Channel to protect the initial assault. However, the German ground forces were delayed at the "Stop Lines" (e.g. the GHQ Line), a layered series of defensive positions that had been built, each a combination of Home Guard troops and physical barriers. At the same time, the regular troops of the British Army were forming up. After only a few days, the Royal Navy was able to reach the Channel from Scapa Flow, cutting off supplies and blocking further reinforcement. Isolated and facing regular troops with armour and artillery, the invasion force was forced to surrender.^[16]

Planned occupation of Britain

This section requires expansion.

Franz Six

Had Operation Sea Lion been launched, six Einsatzgruppen under Dr. Franz Six were to follow the invasion force to Great Britain to establish the New Order. They were provided with a list (known as The Black Book) of 2,820 people to be arrested immediately.

The RSHA planned to take over the Ministry of Information, to close the major news agencies and to take control of all of the newspapers. Anti-German newspapers were to be closed down.^[17]

The OKW, RSHA and the Foreign Ministry compiled lists of those they thought could be trusted to form a new government along the lines of that in occupied Norway. The list was headed by Oswald Mosley. The RSHA also felt that Harold Nicolson might prove useful in this role.^[18]

In fiction

There is a large corpus of works set in an alternative history where the German invasion of Britain is attempted or successfully carried out. These include:

• Novels and short stories
  • Against the Day, Through the Night and In the Morning by Michael Cronin
  • Collaborator by Murray Davies
  • SS-GB by Len Deighton
  • Invasion: Alternative History of the German Invasion of England, July 1940, by Kenneth Macksey
  • Weaver:Time's Tapestry, by Stephen Baxter
  • Peace In Our Time (1946 - first performance 1947) by Noel Coward
  • C. S. Forester's volume of short stories Gold from Crete (1971) included "If Hitler had invaded England". This follows the progress of a German invasion fleet from its embarkation in France to its destruction in the fields of Kent, and closely follows the sequence of events reported in the Sandhurst wargame three years later.
  • Resistance by Owen Sheers, which sets the successful invasion in 1944 after a failed invasion of Normandy rather than in 1940
• Film and television
  • Bedknobs and Broomsticks (1971)
  • It Happened Here
  • An Englishman's Castle ^[19]
  • When Hitler Invaded Britain (2004)^[20]
  • Hitler's Britain (2002)^[21]
  • Alberto Cavalcanti's 1942 film Went the Day Well? is centred on a German reconnaissance mission for Sea Lion being eventually repulsed by the efforts of the civilian population of a remote village.
  • In the 1971 film Dad's Army, German paratroopers with photographs vital to the invasion crash land in England.

• Video and board games
  • Turning Point: Fall of Liberty
  • Empire Earth: in the German campaign, the last mission is to carry out Operation Sealion
  • Axis & Allies: while playing as the Axis powers in campaign mode (which has the Axis powers winning the war), Operation Sealion is the mission following the failed invasion of Normandy.
  • War Front: Turning Point
  • Panzer General (1994 SSI video game): Hexfield strategic simulation game: Sea Lion and Sea Lion Plus (the latter with Italian naval support) scenarios are available given major victories in previous operations.
  • Seelowe: a board game produced by Simulations Publications, Inc. in 1974. The game had both September (both army and navy plans) and July scenarios.

See also

• British anti-invasion preparations of World War II
• RAF Fighter Command Order of Battle 1940
• Operation Sealion Order of Battle
• Operation Herkules - The planned German invasion of Malta
• Operation Tannenbaum - The planned German invasion of Switzerland
• Operation Felix - The planned German invasion of Gibraltar
• Fall Grün - The planned German invasion of Ireland.

References

Further reading

• Fleming, Peter (1957). Operation Sea Lion. New York: Simon & Schuster. ISBN 0330242113. 
• Haining, Peter (2004). Where the eagle landed : the mystery of the German invasion of Britain, 1940. London: Robson. ISBN 1861057504. 
• Kieser, Egbert (1987). Cassell Military Classics: Operation Sea Lion: The German Plan To Invade Britain, 1940. Sterling. ISBN 030435208X. 
• Parkinson, Roger (1977). Summer, 1940: The Battle of Britain. David McKay Co.. ISBN 0679507566. 
• Macksey, Ken. Invasion - The Alternate History of the German Invasion of England, July 1940 (1980) Greenhill Books ISBN 1-85367-361-7
• Parkinson, Roger (1977). Summer, 1940: The Battle of Britain. David McKay Co.. ISBN 0679507566

External links

• British Invasion Defences
• Operation Seelöwe directive No.16
• Why Sealion was not a (realistic) option (essay)
• Second essay on the unlikelihood of Sealion
• Sealion: an orthodox view (includes quotes from participants)
• Comparison of Operation Overlord with Operation Sealion
• http://www.probusmossvale.org.au/Military%20History_files/Battle%20of%20Britain%202.pdf
• http://www.operationsealion.com/
• http://www.historylearningsite.co.uk/operation_sealion.htm
• http://www.spartacus.schoolnet.co.uk/2WWsealoin.htm
• http://www.bbc.co.uk/history/worldwars/wwtwo/invasion_ww2_02.shtml