Operation Sea Lion (wargame)

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Operation Sea Lion was a major wargame conducted at Royal Military Academy Sandhurst in 1974. Its aim was to find out what might have happened had Nazi Germany launched Operation Sea Lion, their planned invasion of southeast England during World War II, in September 1940. The wargame was organized by the Daily Telegraph and Dr Paddy Griffith from the Department of War Studies at Sandhurst. The British umpires were Air Chief Marshal Christopher Foxley-Norris, Rear Admiral Teddy Gueritz and Major General Glyn Gilbert. The German umpires were General Adolf Galland (air), Admiral Friedrich Ruge (naval) and General Heinrich Trettner (land). After the game's conclusion, the umpires unanimously concluded that the invasion was a devastating defeat for the German invasion force.


There were two teams of four players each (Land, Sea, Air, Political):

Rudolf Rothenfelder, President of the Fighter Pilots Association in Munich and ex-Luftwaffe officer played Luftwaffe chief Hermann Goering; Professor Rohwer, Director of the Military Institute in Stuttgart, played Adm. Erich Raeder; and Field Marshal Walther von Brauchitsch was played by Colonel Wachasmuth, the Bundeswehr liaison officer at the Staff College. The German players were supported by their Defence Attaché in London, Admiral Schuenemann.[1]

British Prime Minister Winston Churchill was played by Brigadier Page, Assistant Commandant of the RMA Sandhurst. The people who played the British Home Forces Commander-in-Chief, General Sir Alan Brooke, and the First Lord of the Admiralty, Dudley Pound, are not recorded.[2]
The game had a total of 30 participants.[3]

Game preparation and methodology[edit]

There was "a computerised 'Battle of Britain' phase "(the computer filled a whole large room…)" prior to the start of the game. The computerised "Battle of Britain" preliminaries (programmed by Ivan Collier) lasted several days before the main event.[4] Umpires were allowed to make decisions based on their own intuition (like game masters in a role playing game) and not in the way wargames are usually played. Preparation involved giving each player a written brief telling them what was known, what was expected of them and how they should behave in the game. Paddy Griffith was the "Grand High Umpire." There were six other 'umpires of first recourse': two for Land, and one each for Railways, Sea, Air and Political.[5] These were: Andy Callan, John Davis, Michael Orr, Dennis Barr, Nigel de Lee and Tony Thomas. They "took 'orders' from the playing teams, and usually fed back routine 'reports' locally, without referring them upwards for higher adjudication by the prestigious team of eight international generals & admirals. That happened only when contentious or controversial issues arose that the 'prestigious team' could constructively debate."[6]


The game was played using a scale model of southeast England, the English Channel, and northern France. Available troops and resources were based on known plans from both sides, and weather conditions were based on contemporary British Admiralty records that had, until then, never been published. The two actual days of the Game were scheduled to cover up to a week of ‘war’, long enough for the outcome to be evident. The game started on September 19, 1940. It ran for 16 hours straight, over a weekend.


The scenario assumed:

  • The German military had taken until September to assemble the shipping necessary for a Channel crossing.
  • The Luftwaffe continued to attack British airfields after September 7, 1940 instead of bombing London but despite continuous attacks up to September 19 had not established air supremacy.[7]
  • The Luftwaffe bombed London.
  • The Germans had only converted river barges available as transport ships. Not a great deal was known about the invasion fleet at the time of the wargame. This represented a gross simplification relative to shipping plans discovered later, which involved nearly 4,000 vessels, including 150 merchant ships and 237 light or auxiliary close escorts, in four invasion fleets.
  • The only ships available to defend the invasion fleet were some U-boats, E-boats and destroyers.
  • The invasion fleet was largely unmolested in the crossing, as the Royal Navy ships had to steam south from their bases as far away as Scotland to reach the invasion beaches.
  • The bombing of London would destroy railways between East Anglia and the invasion beaches in Kent and Sussex, so that British troops could not be redeployed quickly. This actually happened on September 7, 1940, when all the railways running south from London were cut and took a long time to repair due to the use (for the first time) of delayed action time bombs.[8]
  • Operation Herbstreise was enlarged to make 10,000 men available for a landing in East Anglia, northern England, Scotland, or Iceland (in real life there were three divisions of infantry involved).[9]
  • The Channel Guns had no effect.
  • The Home Fleet would send its capital ships south. In real life, both Admiral Charles Forbes, commander of the Home Fleet, and Admiral Dudley Pound, First Sea Lord, said they would not send capital ships into the Channel unless the Germans did so, too.

The First Two Days[edit]

The game started on September 19, 1940 but the Germans decided that the sea was too rough to attempt a landing. The same happened the next day. The first two days of game time therefore consisted of air battles, movement of British units to the south coast, the launching of Operation Herbstreise, and embarkation of German units at the French Channel ports. The Luftwaffe bombed Britain's south coast and laid mines in the Harwich, Humber and Thames estuary waters. The Germans landed their Herbstreise diversion force in Iceland and laid protective minefields. The British took full advantage of their intelligence coup (the huge map only showed SE England) and the two day delay by moving four more divisions to Saffron Walden, Newbury, Crowborough and Royal Tunbridge Wells to bolster the nine already in East Anglia, Kent and Sussex. "Churchill" refused to divert any troops in response to the Iceland invasion.[10] Paddy Griffith was very disappointed with the map, which he says was unnecessary and on which he wasn't consulted. "On the day of the game its mere existence had the instant, deeply unfortunate effect of revealing to the British team that the invasion would certainly land in Kent, rather than in East Anglia, or wherever else the umpire team had been trying hard the German's deception plan sound convincing." [11] The map only included the English coast between Portsmouth and Ipswich, and should have at least included East Anglia, as that is where the real British high command expected the invasion.

On the afternoon of September 21, the wind dropped, and the forecast for the next day improved. The German protective minefields were finished, stretching out from the North Foreland. The first wave invasion fleets began to form up at dusk, and begin to cross. They were not spotted by the British until 11pm, The Cromwell warning was issued half an hour later (and the church bells rung), and at midnight the Home Fleet was ordered south.


The German attack was launched at dawn on 22 September 1940 and consisted of 8,000 airborne troops and 80,000 infantry landed in amphibious operations. The invasion fleet suffered only minor losses to Motor Torpedo Boats, however the Germans lost about 25% of their unseaworthy barges. During this 24-hour period the Royal Air Force lost 237 aircraft (about 23% of its fighting strength); the Luftwaffe losses amounted to 333, also about 23% of its aircraft. Naval engagements were indecisive at this stage as the Royal Navy was still assembling its main destroyer fleet to attack. The larger ships of the Home Fleet (including battleships, heavy cruisers and aircraft carriers) were not to be committed due to their vulnerability to air attack and U-boats.

The Germans managed to advance a dozen or so miles inland and even captured the ports of Folkestone and Newhaven but the docks at Folkestone had been thoroughly demolished by the British rendering them more or less unusable. British and Commonwealth forces were moved to fully engage in the battle with the first counterattack on 23 September, halting the advance of the Germans towards Hastings and recapturing Newhaven. German paratroops were also pinned down by long-range artillery and harassment by stay-behind forces. At this stage the Germans had few tanks and only light artillery ashore. An increasing shortage of ammunition was slowly forcing them back towards the sea. The Germans asked "Hitler" if the bombing of London could stop and the aircraft used to support the invasion. The request was denied. By dusk on 23 September the Germans had 10 divisions ashore, but most were halted by counterattacks or awaiting supplies and reinforcements.

The second wave of the German invasion was launched on the morning of 24 September, but only the short crossing from Calais and Dunkirk to Kent. At dawn on 24 September the second German landing, which was to include tanks and heavy artillery as well as supplies and men, was intercepted by a Royal Navy fleet of 17 cruisers and 57 destroyers plus Motor Torpedo Boats. 65% of the German barges, three German destroyers and seven E-boats were sunk for the loss of only two British destroyers (sunk by U-boats) plus two cruisers and four destroyers damaged. Some of the faster German ships broke away and headed for Folkestone, but the port was so badly damaged they could not unload. With the Royal Navy suffering only minor losses, the Home Fleet was ordered to stand by to sail for the English Channel. The German divisions ashore only had enough ammunition for 2 to 7 more days of fighting. Fast steamers and ferries were pressed into service to start an evacuation of German troops from Folkestone and Rye. "Hitler" ordered the remaining reserves to stand down and prepare for redeployment to Poland. Further British air and sea attacks disrupted the German evacuation over the subsequent four days. The remaining German troops in England finally surrendered on 28 September.


The German navy's relative weakness, combined with the Luftwaffe's lack of air supremacy, meant it was not able to prevent the Royal Navy from interfering with the planned Channel crossings. The Navy's destruction of the second invasion wave prevented resupply and reinforcement of the landed troops, as well the arrival of more artillery and tanks. This made the position of the initially successful invasion force untenable; it suffered further casualties during the attempted evacuation. Of the 90,000 German troops who landed only 15,400 returned to France. 33,000 were taken prisoner, 26,000 were killed in the fighting and 15,000 drowned in the English Channel. All six umpires deemed the invasion a resounding failure.


  1. ^ Griffith, 2009, p. 203
  2. ^ Griffith, 2009, p. 205
  3. ^ Griffith, 2009, p. 27
  4. ^ Griffith, 2009, p. 27
  5. ^ Griffith, 2009, p. 27
  6. ^ Griffith, 2009, p. 210
  7. ^ Griffith, 2009, p. 210, note (e)
  8. ^ Griffith, 2009, p. 204
  9. ^ Griffith, 2009, p. 204
  10. ^ Griffith, 2009, p. 205
  11. ^ Griffith, 2009 p. 210, note (b)
  • Cox, Richard (1982) [paperback; original publication 1977]. Operation Sealion. Random House. ISBN 0-09-928440-5.
  • Griffith, Paddy (2009) [paperback;]. Sprawling Wargames- Multiplayer Wargaming. John Curry. ISBN 978-1-4452-0299-0.
  • The Daily Telegraph Magazine No.497, May 17, 1974, pp. 14–21

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