Editing Operation Sea Lion (section)

== Background ==
Adolf Hitler hoped for a negotiated peace with the UK and made no preparations for [[amphibious warfare|amphibious assault]] on Britain until the [[Fall of France]]. At the time, the only forces with experience and modern equipment for such landings were the Japanese, which they used during the [[Battle of Wuhan]] in 1938.{{sfn|Deighton|1996|pp=23–26}}

=== Outbreak of war and fall of Poland ===
In September 1939, the successful<ref>
* [[Richard Overy|Overy, R. J.]] (1998) ''The Origins of the Second World War'' London: Longmans. p. 84 {{isbn|0-582-29085-6}}
* [[John Keegan|Keegan, John]] (1986) ''The Second World War'' New York: Morrow. p. 76
* [[Alan Bullock|Bullock, Alan]] ''Hitler and Stalin'' New York: Knopf. p. 644. {{isbn|0-394-58601-8}}
* [[Richard J. Evans|Evans, Richard J.]] (2008) ''[[The Third Reich at War]]'' New York: Penguin. p. 6 {{isbn|978-0-14-311671-4}}</ref> German [[invasion of Poland]] infringed on both [[Franco-Polish alliance (1921)|a French]] and [[Anglo-Polish military alliance|a British]] alliance with Poland and both countries declared war on Germany. On 9 October, Hitler's "Directive No. 6 for the Conduct of the War" planned an offensive to defeat these allies and "win as much territory as possible in Holland, Belgium, and northern France to serve as a base for the successful prosecution of the air and sea war against England".<ref name="Directive 6">{{harvnb | Murray | 2002 | pp=[http://www.ibiblio.org/hyperwar/AAF/AAF-Luftwaffe/AAF-Luftwaffe-2.html#fn28 32–33, 35]}}, [http://der-fuehrer.org/reden/english/wardirectives/06.html Directive No. 6 for the Conduct of the War] {{webarchive|url=https://web.archive.org/web/20160729073651/http://der-fuehrer.org/reden/english/wardirectives/06.html |date=29 July 2016 }}, Berlin, 9 October 1939</ref>

With the prospect of the Channel ports falling under ''[[Kriegsmarine]]'' (German Navy) control, Grand Admiral (''[[Großadmiral]]'') [[Erich Raeder]] (head of the ''Kriegsmarine'') attempted to anticipate the obvious next step that might entail and instructed his operations officer, ''[[Kapitän zur See|Kapitän]]'' [[Hansjürgen Reinicke]], to draw up a document examining "the possibility of troop landings in England should the future progress of the war make the problem arise". Reinicke spent five days on this study and set forth the following prerequisites:
* Eliminating or sealing off [[Royal Navy]] forces from the landing and approach areas.
* Eliminating the [[Royal Air Force]].
* Destroying all Royal Navy units in the coastal zone.
* Preventing [[Royal Navy Submarine Service|British submarine]] action against the landing fleet.<ref name=Ansel43>Ansel, p. 43</ref>
On 22 November 1939, the Head of ''[[Luftwaffe]]'' (German Air Force) intelligence [[Joseph Schmid|Joseph "Beppo" Schmid]] presented his "Proposal for the Conduct of Air Warfare", which argued for a [[Blockade of Germany (1939–45)|counter to the British blockade]] and said "Key is to paralyse the British trade" by blocking imports to Britain and attacking seaports. The OKW (''[[Oberkommando der Wehrmacht]]'' or "High Command of the Armed Forces") considered the options and Hitler's 29 November "Directive No. 9 – Instructions For Warfare Against The Economy of the Enemy" stated that once the coast had been secured, the ''Luftwaffe'' and ''Kriegsmarine'' were to [[blockade]] UK ports with sea mines, attack shipping and warships, and make air attacks on shore installations and industrial production. This directive remained in force in the first phase of the Battle of Britain.<ref name="Directive 9">{{harvnb| Overy | 2013 | p=68}}, [http://der-fuehrer.org/reden/english/wardirectives/09.html Directive No. 9 – Instructions For Warfare Against The Economy of the Enemy] {{webarchive|url=https://web.archive.org/web/20160304050359/http://der-fuehrer.org/reden/english/wardirectives/09.html |date=4 March 2016 }}, Berlin, 29 November 1939.</ref>

[[File:The British Army in France 1939 O86.jpg|thumb|British soldiers in France in 1939]]
In December 1939, the [[German Army (Wehrmacht)|German Army]] issued its own study paper (designated ''Nordwest'') and solicited opinions and input from both the ''Kriegsmarine'' and the ''Luftwaffe''. The paper outlined an assault on England's eastern coast between [[The Wash]] and the [[River Thames]] by troops crossing the [[North Sea]] from ports in the [[Low Countries]]. It suggested airborne troops as well as seaborne landings of 100,000 infantry in [[East Anglia]], transported by the ''Kriegsmarine'', which was also to prevent Royal Navy ships from getting through the Channel, while the ''Luftwaffe'' had to control airspace over the landings. The ''Kriegsmarine'' response was focused on pointing out the many difficulties to be surmounted if invading England was to be a viable option. It could not envisage taking on the Royal Navy [[Home Fleet]] and said it would take a year to organise shipping for the troops. ''[[Reichsmarschall]]'' [[Hermann Göring]], head of the ''Luftwaffe'', responded with a single-page letter in which he stated, "[A] combined operation having the objective of landing in England must be rejected. It could only be the final act of an already victorious war against Britain as otherwise the preconditions for success of a combined operation would not be met".<ref name=Ansel47-49>Ansel, pp. 47–49</ref>{{sfn|Bishop|2009|pp=106–07}}

=== The fall of France ===
Germany's swift and successful [[Battle of France|occupation of France and the Low Countries]] gained control of the Channel coast, facing what Schmid's 1939 report called their "most dangerous enemy". Raeder met Hitler on 21 May 1940 and raised the topic of invasion, but he warned of the risks and expressed a preference for blockade by air, submarines and [[Commerce raiding|raiders]].{{sfn | Bungay | 2000 | pp=31–33}}{{sfn| Overy | 2013 | pp=68–69}}

By the end of May, the ''Kriegsmarine'' had become even more opposed to invading Britain following its costly victory in [[Norwegian campaign|Norway]]; after [[Operation Weserübung]], the ''Kriegsmarine'' had only one heavy cruiser, two light cruisers, and four destroyers available for operations.<ref>Murray, Williamson & Millet, Alan ''A War To Be Won'' (Harvard: Belknap Press, 2000), p. 66.</ref> Raeder was strongly opposed to Sea Lion, for over half of the ''Kriegsmarine'' surface fleet had been either sunk or badly damaged in ''Weserübung'', and his service was hopelessly outnumbered by the ships of the Royal Navy.<ref>Murray & Millet, p. 84.</ref> British parliamentarians still arguing for peace negotiations were defeated in the [[May 1940 War Cabinet Crisis]], but throughout July the Germans continued with attempts to find a diplomatic solution.{{sfn|Bungay|2000|pp=9–13}}

=== Invasion planning ===
In a report presented on 30 June, OKW Chief of Staff [[Alfred Jodl]] reviewed options to increase pressure on Britain to agree to a negotiated peace. The first priority was to eliminate the [[Royal Air Force]] and gain [[air supremacy]]. Intensified air attacks against shipping and the economy could affect food supplies and civilian morale in the long term. Reprisal attacks of terror bombing had the potential to cause quicker capitulation but the effect on morale was uncertain. Once the Luftwaffe had control of the air and the British economy had been weakened, an invasion would be a last resort or a final strike ("''Todesstoss''") after the UK had already been practically defeated, but could have a quick result.{{sfn | Bungay | 2000 | pp=31–33}}{{sfn | Murray | 2002 | pp=[http://www.ibiblio.org/hyperwar/AAF/AAF-Luftwaffe/AAF-Luftwaffe-2.html#cn76 44–45]}} At a meeting that day, OKH Chief of General Staff [[Franz Halder]] heard from Secretary of State [[Ernst von Weizsäcker]] that Hitler had turned his attention to Russia. Halder met Admiral [[Otto Schniewind]] on 1 July, and they shared views without understanding each other's position. Both thought that air superiority was needed first, and could make the invasion unnecessary. They agreed that minefields and U-boats could limit the threat posed by the Royal Navy; Schniewind emphasised the significance of weather conditions.{{sfn | Bungay | 2000 | p=110}}

On 2 July, the OKW asked the services to start preliminary planning for an invasion, as Hitler had concluded that invasion would be achievable in certain conditions, the first of which was command of the air, and specifically asked the ''Luftwaffe'' when this would be achieved. On 4 July, after asking General [[Erich Marcks]] to begin planning an attack on Russia, Halder heard from the ''Luftwaffe'' that they planned to eliminate the RAF, destroying its aircraft manufacturing and supply systems, with damage to naval forces as a secondary aim. A ''Luftwaffe'' report presented to the OKW at a meeting on 11 July said that it would take 14 to 28 days to achieve air superiority. The meeting also heard that Britain was discussing an agreement with Russia. On the same day, Grand Admiral Raeder visited Hitler at the [[Berghof (residence)|Berghof]] to persuade him that the best way to pressure the British into a peace agreement would be a siege combining air and submarine attacks. Hitler agreed with him that invasion would be a last resort.{{sfn|Bungay|2000|pp=110–11}}

Jodl set out the OKW proposals for the proposed invasion in a memorandum issued on 12 July, which described operation Löwe (Lion) as "a river crossing on a broad front", irritating the ''Kriegsmarine''. On 13 July, Hitler met Field Marshal [[Walther von Brauchitsch|von Brauchitsch]] and Halder at [[Berchtesgaden]] and they presented detailed plans prepared by the army on the assumption that the navy would provide safe transport.{{sfn|Bungay|2000|p= 111}} To the surprise of Von Brauchitsch and Halder, and completely at odds with his normal practice, Hitler did not ask any questions about specific operations, had no interest in details, and made no recommendations to improve the plans; instead, he simply told OKW to start preparations.{{sfn|Bishop|2009|pp=105}}

==== Directive No. 16: Operation Sea Lion ====
On 16 July 1940 Hitler issued [[Führer Directive]] No. 16, setting in motion preparations for a landing in Britain. He prefaced the order by stating: "As England, despite her hopeless military situation, still shows no signs of willingness to come to terms, I have decided to prepare, and if necessary to carry out, a landing operation against her. This operation aimed to eliminate the English Motherland as a base from which the war against Germany can be continued, and, if necessary, to occupy the country completely." The code name for the invasion was ''Seelöwe'', "Sea Lion".<ref name="Führer Directive 16">{{cite web
| title       = Directive No. 16 – On preparations for a landing operation against England
| place       = Führer Headquarters
| date        = 16 July 1940
| url         = http://www.alternatewars.com/WW2/WW2_Documents/Fuhrer_Directives/FD_16.htm
| access-date  = 11 February 2016
| url-status     = live
| archive-url  = https://web.archive.org/web/20160303194212/http://www.alternatewars.com/WW2/WW2_Documents/Fuhrer_Directives/FD_16.htm
| archive-date = 3 March 2016
}}</ref><ref name=Cox159>Cox, p. 159</ref>

Hitler's directive set four conditions for the invasion to occur:<ref name=Cox160>Cox, p. 160</ref>
* 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 [[Strait 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 ultimately placed responsibility for Sea Lion{{'}}s success squarely on the shoulders of Raeder and Göring, neither of whom had the slightest enthusiasm for the venture and, in fact, did little to hide their opposition to it.<ref name=Cox157>Cox, p. 157</ref> Nor did Directive 16 provide for a combined operational headquarters, similar to the Allies' creation of the [[Supreme Headquarters Allied Expeditionary Force]] (SHAEF) for the later Normandy landings, under which all three service branches (Army, Navy, and Air Force) could work together to plan, co-ordinate, and execute such a complex undertaking.<ref name=Cox161>Cox, p. 161</ref>

The invasion was to be on a broad front, from around [[Ramsgate]] to beyond the [[Isle of Wight]].
Preparations, including overcoming the RAF, were to be in place by mid August.<ref name="Führer Directive 16" />{{sfn | Bungay | 2000 | pp=110–11}}

==== Discussion ====
Grand Admiral Raeder sent a memorandum to OKW on 19 July, complaining about the onus placed on the navy in relation to the army and air force, and stating that the navy would be unable to achieve its objectives.{{sfn | Bungay | 2000 | p=111}}

The first joint services conference on the proposed invasion was held by Hitler in Berlin on 21 July, with Raeder, Brauchitsch, and ''Luftwaffe'' Chief of Staff [[Hans Jeschonnek]]. Hitler told them that the British had no hope of survival, and ought to negotiate, but were hoping to get Russia to intervene and halt German oil supplies. Invasion was very risky, and he asked them if direct attacks by air and submarine could take effect by mid September. Jeschonnek proposed large bombing attacks so that responding RAF fighters could be shot down. The idea that invasion could be a surprise "river crossing" was dismissed by Raeder, and the navy could not complete its preparations by mid August. Hitler wanted the air attack to commence early in August and, if it succeeded, the invasion was to start around 25 August before weather deteriorated. Hitler's main interest was the question of countering potential Russian intervention. Halder outlined his first thoughts on defeating Russian forces. Detailed plans were to be made to [[Operation Barbarossa|attack the Soviet Union]].{{sfn | Bungay | 2000 | pp=112–13}}

Raeder met Hitler on 25 July to report on navy progress: they were not sure if preparations could be completed during August: he was to present plans at a conference on 31 July. On 28 July, he told OKW that ten days would be needed to get the first wave of troops across the Channel, even on a much narrower front. Planning was to resume. In his diary, Halder noted that if what Raeder had said was true, "all previous statements by the navy were so much rubbish and we can throw away the whole plan of invasion". On the next day, Halder dismissed the navy's claims and required a new plan.{{sfn | Bungay | 2000 | p=113}}<ref>Burdick and Jacobsen 1988, p. 255.</ref>

The ''Luftwaffe'' announced on 29 July that they could begin a major air attack at the start of August, and their intelligence reports gave them confidence of a decisive result. Half of their bombers were to be kept in reserve to support the invasion. At a meeting with the army, the navy proposed delay until May 1941, when the new battleships {{ship|German battleship|Bismarck||2}} and {{ship|German battleship|Tirpitz||2}} would be ready. A navy memorandum issued on 30 July said invasion would be vulnerable to the Royal Navy, and autumn weather could prevent necessary maintenance of supplies. The OKW assessed alternatives, including attacking the British in the Mediterranean, and favoured extended operations against England while remaining on good terms with Russia.{{sfn | Bungay | 2000 | p=113}}

At the Berghof conference on 31 July, the ''Luftwaffe'' were not represented. Raeder said barge conversions would take until 15 September, leaving the only possible 1940 invasion dates as 22–26 September, when weather was likely to be unsuitable. Landings would have to be on a narrow front and would be better in spring 1941. Hitler wanted the invasion in September as the British army was increasing in strength. After Raeder left, Hitler told von Brauchitsch and Halder that the air attack was to start around 5 August; eight to fourteen days after that, he would decide on the landing operation. London was showing new-found optimism, and he attributed this to their hopes of intervention by Russia, which Germany was to attack in the spring of 1941.{{sfn | Bungay | 2000 | pp=113–14}}

==== Air and sea warfare against England ====
{{Main|Adlertag}}
On 1 August 1940, through Führer Directive No.17, Hitler instructed<ref>{{Cite web|title=Führer Directive 17|url=https://ww2db.com/doc.php?q=301|access-date=2021-08-26|website=WW2DB}}</ref> intensified air and sea warfare to "establish the necessary conditions for the final conquest of England". From 5 August, subject to weather delays, the ''Luftwaffe'' was "to overpower the English Air Force with all the forces at its command, in the shortest possible time." Attacks were then to be made on ports and food stocks, while leaving alone ports to be used in the invasion, and "air attacks on enemy warships and merchant ships may be reduced except where some particularly favourable target happens to present itself." The ''Luftwaffe'' was to keep sufficient forces in reserve for the proposed invasion and was not to target civilians without a direct order from Hitler in response to RAF terror bombing. No decision had been reached on the choice between immediate decisive action and a siege. The Germans hoped the air action would force the British to negotiate and make invasion unnecessary.<ref name="Führer Directive 17">{{cite web
| title       = Directive No. 17 – For the conduct of air and sea warfare against England
| place       = Führer Headquarters
| date        = 1 August 1940
| url         = http://www.alternatewars.com/WW2/WW2_Documents/Fuhrer_Directives/FD_17.htm
| access-date  = 11 February 2016
| url-status     = live
| archive-url  = https://web.archive.org/web/20160303201904/http://www.alternatewars.com/WW2/WW2_Documents/Fuhrer_Directives/FD_17.htm
| archive-date = 3 March 2016
}}</ref>{{sfn | Bungay | 2000 | p=114}}