Directive No. 16: Operation Sea Lion

On 16 July 1940, at the Führer’s headquarters, Adolf Hitler signed the secret “Weisung Nr. 16 für die Kriegführung”, Directive No. 16 on preparations for a landing operation against England. It opened with the sentence: “As England, in spite of her hopeless military situation, shows no signs of being ready to come to an understanding, I have decided to prepare a landing operation against England, and if necessary to carry it out.” Its aim was to eliminate the British homeland as a base from which the war against Germany could be continued and, should it prove necessary, to occupy the whole country. The undertaking was given the code name “Seelöwe”, Sea Lion. The document was drawn up in seven copies, marked “by officer only”, for the commanders of the army, the navy and the air force and for the High Command of the Wehrmacht (OKW).

The decision came in two stages. War chronologies record under 2 July that Hitler “ordered the preparation of plans for an invasion of Britain under the code name Sea Lion”, and under 16 July that he presented the armed forces with a directive on the invasion. The first was the prelude to the second. One detail, however, needs correcting: the order of 2 July was issued by the OKW and signed by its chief, General Wilhelm Keitel, and it did not yet contain any code name. The name “Seelöwe” appeared only in the directive of 16 July. A few days earlier OKW documents had referred to the preparations simply as “Löwe” (“Lion”).

A victor without peace

After the armistice with France, which came into force on 25 June, Hitler was master of the western part of the continent, but the war was not over. Britain, the only enemy left in the field, did not sue for peace. Hitler expected that after France’s defeat London would come to its senses and accept a settlement leaving the continent to Germany and the empire to Britain. He did not know that at the end of May the British War Cabinet, after a bitter dispute, had rejected the idea of sounding out peace terms through Italy (the War Cabinet crisis), and that Winston Churchill had declared in the House of Commons that the British would fight on the beaches and never surrender.

Before 1940 the German staffs had not taken an invasion of the British Isles seriously. In the autumn and winter of 1939 the navy and the army had produced studies on the subject, but the naval staff’s study chiefly listed the difficulties, and the Luftwaffe’s commander, Hermann Göring, replied that a landing could only be the final act of a war against England that had already been won. The Germans had no landing craft and no experience of landing on a defended coast. The first to raise the subject with Hitler was the commander of the navy, Grand Admiral Erich Raeder, on 21 May and 20 June 1940, but more to forestall the army’s ideas than out of conviction. Raeder preferred to strangle Britain by blockade, using U-boats and aircraft. After the Norwegian campaign his fleet was in a sorry state: he had lost a heavy cruiser, two light cruisers and ten destroyers there, and both battleships and other ships were under repair.

On 30 June the chief of the OKW operations staff, General Alfred Jodl, submitted a memorandum on the further conduct of the war against England. He proposed first destroying the Royal Air Force, then attacking shipping, ports and industry, and possibly also terrorising the population with air raids. A landing was to be a last resort, a “death blow” to a country already defeated in the air and at sea. Jodl also pointed to an indirect approach: a strike, together with Italy and perhaps Spain, at British positions in the Mediterranean, at Gibraltar and on the Suez Canal.

Keitel’s order of 2 July

On 2 July Keitel sent the high commands of the three services a paper entitled “The conduct of the war against England”. It stated that the Führer and Supreme Commander of the Wehrmacht considered a landing in England possible, provided that air superiority could be won and several other conditions met. The date remained open, but preparations were to begin at once, on the understanding that for the time being this was a plan and not a decision. The navy was to examine where strong ground forces, reckoned at 25–40 divisions, could land and to estimate the tonnage needed to carry them. The army was to assess British strength and coastal defences, and the Luftwaffe was to say whether and when it would win air superiority and to compare its own forces with the British.

The paper went out on the day the Germans, occupying one after another of the Channel Islands, took Alderney, and the day before the Royal Navy opened fire on the French fleet at Mers-el-Kébir. That action deprived Hitler of any chance that French warships might one day change the balance of power at sea, and at the same time showed that Churchill’s government had no thought of capitulating.

In the days that followed the staffs worked in parallel, each in its own way. The Chief of the Army General Staff, General Franz Halder, and the chief of staff of the Naval War Staff, Admiral Otto Schniewind, agreed on 1 July that air superiority came first, but failed to see eye to eye on the crossing itself. On 10 July the Luftwaffe began its attacks on convoys in the English Channel, from which the British date the beginning of the Battle of Britain. On 11 July, at the Berghof, Raeder again argued to Hitler that a landing should be a last resort, and on the same day the Luftwaffe told the OKW that it would need two to four weeks to smash the RAF. On 12 July Jodl described Operation “Lion” in a memorandum as “a river crossing on a broad front”, which the navy received with irritation, since the Channel is not a river. On 13 July the Commander-in-Chief of the Army, General Walther von Brauchitsch, and Halder presented the army’s plan to Hitler. To their surprise Hitler asked not a single detailed question and ordered preparations to begin. Halder noted in his diary that day that what puzzled the Führer most was why England did not want peace, and that he saw the answer in Britain’s hopes of Russia.

What the directive ordered

Directive No. 16 was short but precise. The landing was to take the form of a surprise crossing on a broad front, from roughly Ramsgate in Kent to the area west of the Isle of Wight. In it the Luftwaffe was to play the role of artillery and the navy that of engineers ferrying troops across a river. Each service was also to consider whether it would be worth carrying out subsidiary operations before the main landing, for example seizing the Isle of Wight or Cornwall. Preparations for the whole operation were to be completed by mid-August.

The most important point was the second, which listed the conditions without which a landing was impossible:

• the British air force had to be so reduced, “morally and physically”, that it could no longer show any appreciable offensive strength against the German crossing;
• mine-free channels were to be cleared in the Channel;
• dense minefields were to seal off the Strait of Dover on both flanks and the western entrance to the Channel, roughly along the line Alderney–Portland;
• strong coastal artillery was to dominate and cover with its fire the coastal waters off the shore;
• immediately before the crossing it was desirable to tie down the British fleet in the North Sea and, through the Italians, in the Mediterranean, and in the meantime the warships stationed in home waters were to be harassed by air and torpedo attacks.

The directive divided the tasks. The army was to draw up the plan of operations and of the crossing of the first wave, allocate the crossing equipment and, in agreement with the navy, fix the embarkation and landing points. The Kriegsmarine was to assemble shipping, using vessels of the defeated countries as far as possible, bring it to the embarkation ports, protect the crossing on both flanks and take charge of all coastal artillery. The heaviest guns facing Dover were to be placed in concrete emplacements able to withstand the heaviest bombs, and their construction was entrusted to the Todt Organisation. The Luftwaffe was to prevent the enemy air force from operating, destroy coastal batteries, break the first resistance of the ground troops, smash approaching reserves and attack warships while they were still far from the crossing points. Göring was also to submit proposals for the use of paratroops and airborne forces.

Hitler himself was to be in command, with the commanders of the three services under him, acting on his guidelines. From 1 August their headquarters were to be no more than 50 kilometres from the Führer’s headquarters at Ziegenberg in Hesse, and the army and navy headquarters preferably together at Giessen. No joint command of the operation, with a single staff planning the actions of all three services, was envisaged. The directive thus shifted the burden of success onto Raeder and Göring, neither of whom believed in the landing.

The army against the navy

The army’s plan had a sweep worthy of the French campaign. Field Marshal Gerd von Rundstedt’s Army Group A was to land three armies: General Ernst Busch’s 16th Army, sailing from ports between Rotterdam and Calais, on the coast of Kent; General Adolf Strauss’s 9th Army, from the Boulogne and Le Havre area, on the coast of Sussex; and the 6th Army, from Cherbourg, in Lyme Bay in Dorset. Thirteen infantry and mountain divisions were to cross in the first wave, followed by armoured and motorised divisions, nearly thirty divisions in all, supported by paratroops.

The navy regarded this as a pipe dream. On 19 July Raeder sent the OKW a memorandum complaining that the directive laid on the fleet a burden beyond its strength. The Kriegsmarine had neither landing craft nor enough escorts, and to carry the troops it would have to bring in river barges from the rivers and canals of Germany, the Netherlands, Belgium and France, most of them without engines of their own. On 21 July, at the first conference devoted to the landing, Raeder told Hitler that the landing could not be carried out like a river crossing and that the fleet would not be ready by mid-August. On 25 July the navy calculated that it would need 155 transports, 1,722 barges, 471 tugs and 1,161 motor boats. At the end of July it stated that ten days would be needed to carry the first wave alone, and that on a narrow front. Halder noted that if this was true, all the navy’s previous assurances had been nonsense and the whole invasion plan could be thrown away. At the beginning of August, in a conversation with Schniewind, he compared a landing on a narrow sector to pushing soldiers through a mincing machine.

The dispute over the width of the front dragged on for several weeks. At the end of August Hitler imposed a compromise that satisfied no one: the nine first-wave divisions of the 16th and 9th Armies were to land on the stretch from Folkestone to the area around Brighton, while the 6th Army was held in reserve.

The “appeal to reason”

Hitler still preferred the British to give way without a fight. On the evening of 19 July, three days after signing the directive, he addressed the Reichstag, which since the fire in its building in 1933 had been meeting in Berlin’s Kroll Opera House. He reviewed the course of the war, appointed Göring Reich Marshal (Reichsmarschall) and promoted twelve generals to field marshal. Among them were Keitel, Brauchitsch, Rundstedt, Fedor von Bock, Wilhelm von Leeb, Walther von Reichenau and, from the Luftwaffe, Albert Kesselring, Hugo Sperrle and Erhard Milch. Towards the end he turned to Britain. He said he had never intended to destroy the British Empire, warned that if the struggle went on it would end with the annihilation of one of the adversaries, and declared that he felt obliged, “as the victor”, to appeal once more to England’s reason. “I can see no reason why this war must go on,” he said. He named no concrete terms. From his words and their context it was clear that Germany would keep everything it had won.

In London the answer came sooner than the government wished. Less than an hour after the speech the journalist Sefton Delmer, who presented the BBC’s German-language broadcasts, rejected the “appeal to reason” on the air on his own initiative and told Hitler that the British were hurling it right back “into your evil-smelling teeth”. In Berlin it was assumed that he must have had the government’s approval. Churchill decided not to reply himself, saying that he did not propose to comment on Hitler’s speech because he was “not on speaking terms” with him. The task fell to the Foreign Secretary, Lord Halifax, the same man who in May had favoured sounding out peace terms. In a radio broadcast on 22 July he said that Hitler’s only argument was fear and his only arguments were threats. “We shall not stop fighting till freedom, for ourselves and others, is secure,” he declared. The British government sent no official reply.

On 19 July another decision was taken in London. Churchill replaced General Edmund Ironside as Commander-in-Chief, Home Forces, responsible for defending the island against invasion, with General Alan Brooke. Ironside had relied on static lines of fortifications inland; Brooke wanted strong reserves capable of counter-attacking quickly on the beaches. Behind him stood poorly armed divisions that were rebuilding over the summer after the evacuation from Dunkirk, and hundreds of thousands of volunteers of the Local Defence Volunteers. In the same weeks Polish soldiers and airmen evacuated from France arrived in Britain.

The last day of July

With his “appeal” rejected, Hitler had to choose what to do next. On 31 July, at the Berghof, Raeder reported that converting the barges would take until mid-September, and that the only possible dates for a landing in 1940 were 22–26 September, when the weather in the Channel usually begins to deteriorate. He would have preferred to postpone the operation until May 1941. Hitler insisted on September, because the British army was growing every week. He decided that from the beginning of August the Luftwaffe would strike at the RAF with full force, and that after a week or two he would decide whether the landing would take place. After Raeder had left, he told Brauchitsch and Halder something that weighed more than the whole directive: England was counting on Russia and America, so if Russia were defeated, England’s last hope would be gone. The Soviet Union was to be attacked in the spring of 1941.

Place in the war

Directive No. 16 was the first and only serious German plan for the conquest of Britain. On 1 August Hitler issued Directive No. 17, which ordered the Luftwaffe to destroy the British air force as quickly as possible, and on 13 August, Eagle Day, the main phase of the Battle of Britain began. Everything else depended on whether the Luftwaffe won air superiority. Ships and barges were assembled in the ports from Rotterdam to Le Havre. On 19 September there were 168 transports, almost two thousand barges, 420 tugs and around 1,600 motor boats there, and British bombers attacked them systematically. Meanwhile the Reich Security Main Office had prepared a list of people to be arrested once the island was occupied (the Sonderfahndungsliste G.B.), containing, according to the most commonly cited figures, around 2,800 names of politicians, writers, journalists and émigrés, among them Churchill and Sefton Delmer.

The directive’s condition was not met. The RAF refused to be beaten, and in September the Luftwaffe shifted the weight of its raids to London. The date of the landing was provisionally set for 21 September and then postponed, and on 17 September Hitler deferred the operation indefinitely. On 12 October he put it off until the spring of 1941, and the assembled barges began to be returned to inland shipping. On 18 December 1940 Hitler signed Directive No. 21 on the attack on the Soviet Union, and Sea Lion became no more than a smokescreen for the preparations in the east. It was never formally cancelled. The navy’s last order on the matter, suspending preparatory work, dates from February 1944.

Historians still argue over whether Hitler really intended to land in England, or whether the directive was above all a means of pressure to force London into negotiations. His words “prepare, and if necessary carry out” and his lack of interest in the details tend to support the latter view. Most scholars believe that the landing, even after victory in the air, would have ended in disaster, because the weak Kriegsmarine could not hold off the Royal Navy for long, and slow convoys of barges towed across the Channel would have been easy targets. The most important outcome of the summer of 1940, however, was that Britain survived. The island that Hitler had managed neither to persuade nor to conquer became, a few years later, the base from which the Allies landed in Normandy in June 1944.