Sealion - What if Germany had invaded Britain in 1940?

If you look across the English Channel from Calais, on a good day you can often make out the white cliffs of Dover, not 20 miles away. Imagine then the anticipation of a German soldier, standing on the Atlantic Coast of France 700km from Germany, with the last enemy literally in sight but perhaps 20 miles too far away.

The Germans were faced with an unenviable task in June 1940 if they wanted to take Britain out of the war. The small island had not been invaded by a foreign power since the 12th Century and had resisted all subsequent attempts. The British Armed Forces, in particular the eminently powerful Royal Navy, stood guard, a bastion against anyone foolish enough to try.

The Germany Army was well equipped (if overly reliant on horses), battle hardened and as large as, if not larger than the British Army. The Luftwaffe seemed more than a match for the RAF as well, being particularly skilled in tactical operations, having supported the army through Poland, Belgium, Holland and France, and numerically superior. The Kriegsmarine (the German navy) was sorely lacking however. Yes, they boasted powerful vessels like Bismarck, Scharnhorst and Gneisenau, but they were numerically inferior to their British counterparts and singular, powerful battleships are of less use in the narrow confines of the English Channel than Destroyers and Cruisers.

Let us assume, however, that the Germans were able to meet these challenges, destroying the RAF and successfully protecting their landing zones from naval interference. According to Hitler’s Fuhrer Directive No. 16, the invasion force would have landed on a wide front from Ramsgate to the Isle of Wight, using upwards of 40 divisions, 17 in the first wave. With troops successfully ashore, the first objectives would have been the ports at Dover and Folkestone.

As the Allies realised during their own amphibious operations, securing a port as early as possible was critical to maintaining the invasion force. On D-Day, Cherbourg and Ouistreham were priority targets, however Allied Command also created prefabricated docks known as the Mulberry Harbours to help land equipment and supplies. The Kriegsmarine had been working on a similar project called a “heavy landing bridge” prior to the Battle of Britain. Two prototypes had been built and successfully tested on the Channel Islands and likely would have been used during Sea Lion. The prototypes were so successful, sturdy and well-built that they remained on the Channel Islands until the 1970s.

With a beachhead established, ports secured, and an airfield captured at RAF Lympne (close to the coast and within easy reach of Hitler’s specified landing zones) it would have been time to push forward. British counter attacks would have been made by the Territorial Reserves and the remains of the army, evacuated from Dunkirk months previously. With droves of equipment abandoned in France during the Dunkirk evacuation, only small numbers of British units would have been fully equipped with their designated allotment of vehicles, artillery and tanks.

Abandoned Equipment left in France following the Dunkirk evacuation - Wikimedia Commons

The Germans, having met British tanks in France, would have been well aware that their general issue anti-tank guns like the PaK36 (PanzerabwehrKanone) and anti-tank rifles like PzB38 (Panzerbüchse), would not be of much use against British Infantry tanks such as the Matilda II and Valentine III. Thus, they had to make sure their own tanks could make it ashore and they developed two novel ideas, one of which would later be independently developed and used successfully by the British. The first was a ‘Schwimmpanzer II’, essentially a Panzer II tank equipped with flotation devices and buoyancy aids with propellers linked to the tanks’ tracks for propulsion. The Panzer II, however, was an outdated tank before the Germans invaded France and would have been no match for the British. The second idea was ‘Tauchpanzer’, a deep wading tank. This was a Panzer III, a tank built to take on other tanks, with waterproof seals around all sighting ports, hatches and air intakes, with snorkel hoses for oxygen and exhaust floating on the surface. The Tauchpanzer could drive along the sea bed after being dropped off by a barge in a maximum of 15 metres (49 ft.) of water, and provided it kept moving, had been successfully tested near Wilhelmshaven. The Germans had created over 250 tanks for amphibious use, giving them roughly an Armoured Division’s strength, very useful for the initial landing and getting tanks to the Front quickly.

A Matilda II Tank on manoeuvers near Liverpool with 5th Battalion King's Shropshire Light Infantry - Wikimedia Commons

Let’s assume that British counter attacks had failed and the Germans have secured all of their objectives. London would have fallen. Occupation, establishing a military government and disarming any local British Army or Home Guard units would have been a priority. According to H. Lloyd Goodall in ‘A Need to Know’ Hitler planned to use Blenheim Palace, the childhood home of Sir Winston Churchill, as the overall headquarters of the German Occupation Government. There would have been the possibility of restoring Edward VIII to the throne, as per a Channel 5 documentary broadcast in 2009. Edward VIII was believed to be a Nazi sympathiser, a feeling reinforced after he and Wallis Simpson visited Germany in 1937. That rumour has never been properly substantiated, however.

An unfortunate circumstance of many of the German occupations of the Second World War was the removal of cultural artefacts, art and literary works from museums, homes and other sites. According to Norman Longmate in ‘If Britain Had Fallen: The Real Nazi Occupation Plans’, Hitler wanted Department III of the German security service to remove Nelson’s Column and the 4 bronze lions from central London. The edifice was a symbol of British Naval superiority and a victory over the invading forces of Napoleon’s French Republic. To Hitler, removing it would have created a visible and powerful reminder of his victory over the British Empire and his triumph where the great French Emperor had failed. Department III would also have been made responsible for emptying the National Gallery, the British Museum and the Ashmolean Museum, ostensibly for protection; in actual fact, such plundering would have amounted to little more than theft. As a minor side note, Longmate points out that [aside from Nelson’s Column] none of the items wanted by the Germans were where they thought they were. Art, literary works and other precious items from the great museums had already been moved, prior to the outbreak of war, to various country estates and even a quarry in Wales. No doubt they would have been moved further afield had the Germans successfully landed on British shores.

More sinister plans would have been afoot in the Government Offices however. The Gestapo hoped to get British records from the Home Office on all foreigners in England including Irish nationalists, Moscow agents, German emigrants and political prisoners. Gestapo officers would have visited the Foreign Office too, hoping to arrest the head of the Intelligence services. While the immediate aim would have been to identify former friends and past enemies of Germany, the ultimate political aim, according to Longmate, would have been to gather evidence which would embarrass the recent British Government and its Allies. Most significantly, however, the Germans hoped to clarify Anglo-American relations with a view to exposing Roosevelt as interventionist. If there is one thing Germany was good at, it was propaganda, and the next stage would have been the closure of the Ministry of Information, press archives and the newspapers and editorial offices. Once life returned to some semblance of normalcy, some of the newspapers would have been re-opened and distributed once again, albeit with strict censorship and the understanding they would be closed down if they did not adhere to German rules. The BBC would of course also have been a prime target; indeed, broadcasting studios and transmitters were top of Germany’s list. It would have been the main instrument by which the British population would be forced to accept occupation, and every article, broadcast, and show would have served their purposes.

Ultimately, Hitler’s ambitions for the Third Reich stretched beyond the borders of Europe. ‘Lebensraum’ or ‘Living Space’ had always been a central tenant of Hitler’s ambitions, and in particular he had his eye on the vast steppes of the Soviet Union, where the sub-human Slavs, Russians, Ukrainians and Poles could be easily displaced or otherwise removed to facilitate German expansion. To take on the Soviet Union was no easy task. It boasted one of the largest armies and air forces in history, was the largest country in the world by landmass and boasted a leader equally as despotic as Hitler. The German Army needed supplies, men and equipment to combat the Bear while German industry needed materials and workers to supply that equipment. What better way than to strip it from defeated nations, including Britain, which had a wealth of such materials? The German army was predominantly reliant on horses for much of its transportation, ironic considering how well regarded the Germans have become for the quality of their Armoured Divisions. Defeated armies leave behind vast swathes of equipment, much of it useable and the Germans took full advantage of that. The vehicle inventories of Czechoslovakia, Poland, France, Great Britain, and the USSR could be found throughout the German Army during the Second World War. From battle tanks like the Char B1 and T-34 to light tractors such as the Universal (Bren Gun) Carrier and Renault UE Chenillette, all would have been useful to replace horsed transport. Even civilian vehicles could have ended up in military inventories, Longmate makes reference to cyclist battalions in the German Army, requisitioning civilian motor cars where possible.

In addition to actual equipment, the British Armaments Factories would have been re-tooled for German production, be it tanks, aircraft, trucks or rifles. The dockyards and ship building facilities would have proven useful for supporting further Kriegsmarine operations in the Atlantic. Certainly if Hitler wished for a future war with the United States, the Kreigsmarine’s surface fleet would have needed to have been significantly expanded and strengthened to match the United States Navy.

Materials and industry were not the only resources available however; great minds such as Frank Whittle, who worked on the first British jet engine, or Barnes Wallis, the inventor of the famed bouncing bomb, would have been a more than inviting target and of incredible value to German Armaments companies like Messerschmitt and Krupp. Whittle had actually completed a working jet engine prototype by 1940, and would later successfully flight-test the same in 1941 in an aircraft designed and built by Gloster. Imagine if the Messerschmitt ME-262, the first operational jet fighter in the world, had come 2 years earlier than its historical debut in 1944!

ME-262 Jet Fighter, feared by all when it was introduced in 1944, limited numbers and low fuel supplies thankfully kept them mostly at bay - Wikimedia Commons

Fortunately, the above never came about. Hitler indefinitely postponed Operation Seelöwe on 17th September 1940, having been convinced in a meeting with Hermann Göring and Gerd Von Rundstedt that an amphibious invasion was no longer viable. The RAF survived the Luftwaffe’s efforts to destroy it in the Battle of Britain. The Kriegsmarine, meanwhile, had taken disastrous losses during the invasion of Norway, with several light cruisers and destroyers sunk. They barely had the strength to oppose the Royal Navy before the Norwegian operations, and could in no way support an invasion fleet at their current force level. Britain lived to fight on, and with the help of the United States of America, the Soviet Union and many other Allied nations, reversed the tides of war which looked so bleak in June 1940.

To see who would have been targeted by the Gestapo immediately after a successful invasion of Great Britain, take a look at Hitler's Black Book - The Most Wanted List, newly translated from the German version, transcribed exclusively and completely free to view on the Forces War Records site.

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