222: Wait, This is Going to be Complicated

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This episode delves into the high-stakes planning behind Operation Sea Lion, exploring how German military strategists grappled with the immense challenges of invading Britain in 1940. As the Luftwaffe battled for air superiority, the planners faced a critical dilemma: balancing the necessity of an invasion with the uncertain feasibility of achieving the required dominance over the Royal Air Force. Tensions mounted between the German Army and Navy staffs, who had to navigate logistical, tactical, and strategic uncertainties within a tight window of just a few months. With the fate of the invasion hinging on a single, precarious condition—air superiority—the episode reveals the complexity and risks of one of WWII’s most pivotal decisions.

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Summary

This episode delves into the high-stakes planning behind Operation Sea Lion, exploring how German military strategists grappled with the immense challenges of invading Britain in 1940. As the Luftwaffe battled for air superiority, the planners faced a critical dilemma: balancing the necessity of an invasion with the uncertain feasibility of achieving the required dominance over the Royal Air Force. Tensions mounted between the German Army and Navy staffs, who had to navigate logistical, tactical, and strategic uncertainties within a tight window of just a few months [source_id]. With the fate of the invasion hinging on a single, precarious condition—air superiority—the episode reveals the complexity and risks of one of WWII’s most pivotal decisions.

Hello everyone and welcome to History of the Second World War Episode 222 - The Battle About Britain Part 6 - Wait This is Going to be Complicated. This week a big thank you goes out to Ken, Andrew, Andrew, Katie, and Oof tacular for supporting the podcast by becoming members. Members get access to ad-free versions of all of the podcast’s episode plus special member only episodes roughly once a month. Head on over to historyofthesecondworldwar.com/members to find out more. On July 2, 1940 the Commander in Chief of the German armed forces, Field Marshal Wilhelm Keitel, would issue a Supreme Command Directive titled ‘Prosecution of the war against England’. With part of the introduction stating “Invasion of England is quite possible under certain conditions of which the most important is the gaining of air superiority. For the present, therefore, the time at which it will take place remains an open question.”. For the planning staffs that would actually be called upon to plan the invasion, those of the German Army and Navy, they had to just assume that the air campaign would be successful. This episode will look at the actions of those planning staffs as they tried to wrestle with the problem of reconciling what was necessary for a successful invasion and what was possible. All of those problems had to be solved between roughly the middle of July and the middle of August for preparations to be completed in time for the invasion to happen in 1940. It was all going to be so complicated.

While our episodes here will focus just on preparations for the attack directly against the British Isles, there were initially some hopes that the German actions would take on a worldwide scope by involving Italy and Spain. For the Italians, the hope was that they would be threatening the Suez Canal by the time that invasion occurred, and this would split British focus. The Italian military was already fighting in the deserts of North Africa, but advancing deep into Egypt to threaten the canal would prove to be far beyond their capabilities . In the case of Spain there was hope that after the support that Germany had provided to Franco during the Spanish Civil War he could be brought into the current conflict to allow German forces to move through Spain on their way to Gibraltar. This would have greatly compromised not just the British position in the Mediterranean, but also in the Atlantic as the basing of Royal Navy vessels at Gibraltar was an important part of Royal Navy’s strategy. Franco would demand a high price for his involvement, with his concern being that Spain was in no position to participate in any fighting against the British empire. They had, after all, just ended a very bloody and destructive civil war . And so Franco would ask for many things from the Germans, from economic support to weapons, but the most important being that he would only allow German forces to enter into Spain after German forces had landed in Britain. Neither of these plans would bear fruit, and so it was left to the German military to bring the decisive blow to Britain on the quite narrow scope of Southern Britain.

Critical to the invasion plans, and a major driver for how the plans could even be constructed, was the state of the German navy, the Kriegsmarine. And from the largest to the smallest ship involved, there were problems. The largest ship that the Germans had available was one heavy cruiser, the Admiral Hipper, with the larger battleships Scharnhorst and Gneisenau in dry dock due to damage sustained in operations off Norway. There were also three light cruisers, 10 destroyers, and 32 U-boats that would also be operational by late summer 1940. This was, not a lot of naval strength when compared to what the British would be able to call on which was 8 battleships, 21 cruisers, and 50 destroyers, along with countless smaller craft should the need arise. The Germans assumed, quite correctly, that these would be thrown at any invasion fleet from the very beginning, with the Royal Navy’s goal being to overwhelm the German defenders before their invasion even really began. Even if the Kriegsmarine and Luftwaffe could prevent the Royal Navy from disrupting the invasion fleet, a big if but assuming they could, then they had to put men ashore. The Germans had a serious problem with getting men onto the beaches because they did not have any purpose built landing craft to use in the amphibious operation they were being called upon to execute. While this story in quite far in the podcast’s future, one of the interesting evolutions of amphibious warfare during the Second World War, particularly in the Pacific, was the enhancements made to the landing craft used in the operations. They could make or break the critical early hours of an invasion when it was absolutely essential that the landing forces get as much strength as possible onto the beaches to overwhelm any defenses and then prepare for any possible counterattacks that might try and throw them back into the sea. I am guessing that most listeners would mentally picture an allied Landing Craft, Vehicle, Personnel or colloquially known as the Higgins Boat for this purpose. These were used on D-Day and were the boats where the ramp dropped down the front and all around 36 soldiers would rush out the front. These specialized boats revolutionized amphibious operations, and the Germans had nothing even remotely similar. Instead the first waves of the German forces would move across the channel on various ships, minesweepers, motor fishing boats, coastal trawlers, really anything. Then off the coast a few of them would be moved into Type 39 assault boats which only carried 6 men, although it did have a machine gun at the front. Other troops would be rowing ashore on rubber dinghies. These first troops then had to find a way not just to get onto the beaches but also to push the British defenders back because the following waves of forces were even less prepared for a contested landing. This was because all of the men and material for the invasion would be broad across on flat bottomed river barges which were collected over the course of the summer months from Germany, France, and the Low Countries. Eventually over 2,000 of these barges would be available, but that was only at the peak, and due to the time and effort put into collecting them there was very little time for the landing forces to train with them . This meant that many of the forces involved had almost no experience actually loading into and exiting from the barges which was bound to slow things down.

The Kriegsmarine was aware of many of these limitations, and from the beginning they included them in their planning, but the the members of the Army’s General Staff who were also planning were far less concerned about them. This meant that when Admiral Raeder was handed a copy of the Sea Lion plans in late July he was furious, because they had already been presented to Hitler and he had already approved them, and they were impossible. The Army’s plans had been shown to Hitler at a meeting on July 13th, when they would make the argument that the best way to approach the landings was to launch them on a broad front . This would allow for the quick capture of most of Southern England, and given the importance of those areas to British security, the rest of the islands would quickly come under German control. They also included in their plans the objectives of the Kriegsmarine, without consulting with Raeder of course, and they believed the naval objectives should be to seal off the English channel on both sides of the invasion fleet with naval vessels, mines, and coastal artillery in France. Oh, and the Kriegsmarine should also send some of their forces into the North Sea as a distraction. These objectives were completely beyond the power of the Kriegsmarine, to the point of near absurdity, protecting large sections of the English Channel would be difficult by itself, but with the need for diversionary forces, and the requirement to protect the shipping corridors for days, weeks, and months, it was impossible. And that was before even considering the problem of just getting the soldiers and supplies onto the beaches in the quantities demanded by the plans. This resulted in a major disagreement at a meeting on July 21st. Raeder laid down the simple math of the situation, which was that given the available shipping, and the large number of troops involved, it would take 10 days for just the first wave to be landed on all of the beaches. This first wave would be around 90,000 men, so around 9,000 men per day. The Army planners believed that 13 divisions in the first waves would be landed on beaches spanning almost the entire southern coast of England, and that for them to be successful they would have to be landed quickly and all within 1 day, because just three days later that number needed to almost triple to 260,000 men. At that point it would be time to start moving over the critical armored and motorized divisions so that the Germans could start making serious attacks out of their beachheads and into the British countryside. The eventual goal was for 41 divisions in total to be moved across the channel during the first month of the operation. For reference, about 160,000 allied troops would land on D-Day in 1944, so the 90,000 here was smaller than that, but over a series of beaches that were much more spread out along the coast. All of this planning was completely useless though if it took over a week for the first wave to make its way across the channel, which is what Raeder was claiming at the meeting on July 21st. Halder would be recorded as responding ‘If that is true we can throw away the whole plan of invasion’. I know I have mentioned this many times, but Halder was not wrong, an invasion on the scale that the Kriegsmarine could support probably would not work, but equally his plan was not possible. It is almost like the invasion was doomed to fail, but nobody wanted to say it, certainly not after the string of successes enjoyed by the German Wehrmacht up to that point in the war. And so the Chief of the General Staff of the German Army High Command Halder did the only reasonable thing, and simply accused Raeder of lying and simply rejecting Raeder’s transportation estimates. This would not be the last time that Halder would simply choose to believe something that was not true, it would also go poorly during Barbarossa. But Raeder’s estimates were not just based on guesses, and instead there were detailed plans and numbers behind the provided estimates. One of the key individuals in the creation of those detailed plans was Konteradmiral Fricke, who would do the detailed planning on the Kriegsmarine side. It was estimated that the first wave of the Army’s plan, which again included 260,000 men would require at least 2 million tons of total shipping, Fricke did not have anything close to that. Fricke believed that, even if the Army was okay with the lengthier period of time for the landings, just getting the expected 41 divisions across would require the Kriegsmarine to take over all domestic harbors from the German coast, through the Netherlands and Belgium, all the way into France, and they would have to maintain their monopoly on all events in those harbors for 6 weeks. Along with that many more barges would have to be found, and requisitioning them from mostly German rivers would be very detrimental to the German economy and to the war industries that depended on water borne transport of goods throughout Germany. Also, over 24,000 skilled crew members for those barges would also be needed to maintain and operate them, a further drain on German industry. A week later Raeder would inform Halder and the Army High Command that what they wanted was simply not possible, and so they had to come up with a new plan. Raeder would also make it clear that he believed that complete and total air superiority over the English Channel was a prerequisite to the operation, and without it the Kriegsmarine would not support the operation. This demand, while not necessarily unreasonable, was also an impossible goal. For their part, the Army built their entire plan on the assumption that air superiority would be achieved, and that the Luftwaffe would have complete freedom to operate its maximum strength against the Royal Navy’s attempts to intervene.

The last three days of July would be critical to the future of the invasion because on those three days there would a joint planning conference between Army High Command and the Kriegsmarine planning staff. Oddly enough the Luftwaffe was not there. The goal of the conference was to reconcile the differences in views of the two services and arrive at a workable plan for the invasion. But it would be at this meeting that Raeder would lead off with his belief that Sea Lion should simply be postponed . They were already late in the year, and the Naval Staff already insisted that the landings could not occur at all until at least mid September. The Naval Staff made it clear that even in mid September the weather would be “a source of great difficulty”, and it would only get worse as time went on. This was a major concern not just because it was going to take weeks to transport the first wave under the best of conditions, but it also meant that follow on support may be disrupted by winter weather. The problems of weather would also collide with the exact conditions that had to be present for the invasion to be successful, with the goal being to land the first troops at dawn. Landing at dawn meant sailing at night, which required at least some amount of moon light just so that the risk of collisions and accidents was reduced. It was also important that the landing take place under very specific tidal conditions so that the best possible setup was given to the landing craft. The general goal was for high tide to hit just before dawn, just as the initial assault landings were moving in to allow the landing craft to push as far up the beach as possible. Anyone who has been on a beach that is heavily impacted by tidal conditions knows that it can become a very long beach at low tide, and it was possible that such a long beach would be swept by machine guns, a disaster waiting to happen. All of these requirements meant that the best window in September was between the 19th and the 26th. After three days of discussions between the most powerful men in the German military, they still had not come to any kind of real agreement on what the plan should be. Raeder was still insisting that the scale and scope of the invasion be reduced, and the Army leaders were still pushing for the larger scope that they preferred. When this lack of decision was presented to Hitler he simply ordered that preparations continue with a target of the middle of September.

One important factor in the decisions made in August and September was that the final order had to be given 10 days before the start of the invasion, because it would take that long for all of the preparations to be made. They could then be reversed during that 10 day window, until the night before, but the decision had to be made 10 days prior to the invasion day. One of the important drivers of that 10 day window was the requirements that minefields be laid on both sides of the invasion corridor. The Kriegsmarine understood that it did not have the surface ship power to hold off a concerted effort by the Royal Navy, and so they hoped to even the odds a bit through the use of extensive minefields. These would be in the form of multiple mine barriers that would be sown during the 10 days before the invasion. The problem was that the British planned to do the same thing, lay minefields across any areas where an invasion fleet would be sailing. This meant that during the 10 days before the invasion there would have been a mine war, with both the Germans and British frantically positioning minefields, while also trying to sweep as many of the enemy’s mines as possible. Both of these activities would have been happening on a daily basis, with darkness providing cover for both sides to complete their own objectives. The minesweepers would always have the advantage as well, because while the minefields had to be placed over a large expanse of ocean, the sweepers just had to clear a corridor, and this makes it difficult to predict exact what impact the minefields would have had on the invasion force and the Royal Navy’s response.

On August 7th the Naval Staff would present a new plan at another planning conference, and they would propose that instead of the very broad front that the army was proposing the Germans land just between Folkestone and Beachy Head, a distance of around 80 kilometers. Slightly larger than the 64 kilometer width of the Allied landings in Normandy, but much smaller than the initial Army plans. Onto these beaches would be placed just 3 divisions over the course of a few days. One of the major limits that the Naval Staff placed on itself was that they were insistent that the landings could only occur away from major port cities, and therefore as far as possible from any interference by the Royal Navy. This would make supplying the troops more difficult, but could theoretically give the landings a greater chance of success. When this new, much more narrow landing, was proposed to Halder and the Army planners there was immediate concern. Being on a narrow front allowed for the British to concentrate their forces against the beachheads. This made it much more likely that the landings would be contained, and that the front would solidify, making it very difficult to get things moving again due to the difficulty of moving supplies over to the German formations. At the very least Halder wanted a number of smaller landings to take place on other areas of the coast to present multiple problems to the defenders and to spread out their response. Raeder claimed that these were simply not possible given the current capabilities of the naval forces involved. When these other landings were shut down Halder would remark that ‘From the point-of-view of the Army I regard the proposal as complete suicide. I might as well put the assault troops straight through a sausage machine!’. The August 7th meetings once again did not really resolve anything between the two plans, although it did move everybody one step closer together which was critical. Hitler would get involved in mid August to try and bring the disagreements to a close, ordering the cancellation of some of the secondary landings and then ordering the Army Staff to adjust its plans based on the requirements set forth by the Naval Staff. The result would be the plan presented on August 27th, which would be Sea Lion in its mostly final form. The landings would take place along a 130 kilometer stretch of the British coastline, with 10 total divisions being landed in the first wave of the attack. These 10 divisions would establish a beachhead of at least 20 kilometers in depth to provide the security and defensive capabilities to hold off any British counter attacks for at least a week. At that point a second wave of 9 divisions would be landed which included 4 armored and 2 motorized infantry divisions. These forces would make up mobile breakthrough force that would launch their blitzkrieg campaign across the British countryside, hopefully ending the war quite quickly. Even though this represented the final plan, it was still up for changes as time went on, for example the first wave was reduced from 10 divisions down to 9, with the idea being that an airborne division could be added over the days following the initial landings to bulk up up the defensive forces. But all the landings were supposed to happen in between 15 to 18 days, at which point the German army would be off the races.

To close out this episode, this final episode on the planning for Operation Sea Lion we should discuss a bit about how it might have gone if it had went forward. This is because, of course, the planning would the final stage of the Sea Lion operation due to both the events over Britain over the following weeks as well as the fact that by the time that the final plan was arrived at Halder and the other army leaders had begun to lose faith in the operation and its ability to succeed. Raeder and the navy needed very little encouragement to support a delay until 1941, by the end of August 1940 that had been their recommendation for over a month. As with every invasion the result would have been dictated by the British response. A decisive response was critical because it would have caught the German invaders at their weakest, because while the first wave of troops was a total of 9 divisions these would only be landing over a period of several days. That meant that on the first day of the invasion only the equivalent of 3 divisions would actually be on the beaches. Assuming the Royal Navy’s response was somehow turned away, that number would grow but only slowly. I believe that the entire operation would have been a complete debacle. The Royal Air Force would have responded in great strength, beyond what the Luftwaffe could fully prevent, the Royal Navy would have charged in and caused havoc among the invasion fleet, and even the British land forces were better prepared by September to meet the German challenge. Those ground forces will be the focus of next episode as we move to the other side of the English Channel to look at British invasion preparations which began in June 1940 as a frantic dash to throw something together with little hope of success and would grow into a much stronger and prepared force by September when the threat of invasion was at its height.