Adlertag ("Eagle Day") was the first day of Unternehmen Adlerangriff ("Operation Eagle Attack"), which was the codename of a military operation by Nazi Germany's Luftwaffe (German air force) to destroy the British Royal Air Force (RAF). By June 1940, the Allies had been defeated in Western Europe and Scandinavia. Rather than come to terms with Germany, Britain rejected all overtures for a negotiated peace. During the Battle of Britain, Hitler gave the German armed forces (Wehrmacht) a directive (Directive No. 16) that ordered provisional preparations for invasion of Britain. This operation was codenamed Operation Sea Lion (Unternehmen Seelöwe). Before this could be carried out, air superiority or air supremacy was required. The Luftwaffe was to destroy the RAF in order to prevent it from attacking the invasion fleet or providing protection for the Royal Navy's Home Fleet, which might attempt to prevent a landing by sea. On 1 August Hitler gave the Luftwaffes commander-in-chief, Reichsmarschall (Empire Marshal) Hermann Göring and the Oberkommando der Luftwaffe (High Command of the Air Force) a directive (Directive No. 17) to launch the air assault. The essential target was RAF Fighter Command. The service's destruction would deny the British their air superiority asset. Throughout July and early August, the Germans made preparations for Adlertag. The date of the assault was postponed several times because of bad weather. Eventually, it was carried out on 13 August 1940. The German attacks on 13 August inflicted significant damage and casualties on the ground, but, marred by poor intelligence and communication, they did not make a significant impression on Fighter Command's ability to defend British air space. Göring had promised Hitler that Adlertag and Adlerangriff would achieve the results required within days, or at worst weeks. It was meant to be the beginning of the end of RAF Fighter Command, but Adlertag and the following operations failed to destroy the RAF, or gain the necessary local air superiority. As a result, Operation Sea Lion was postponed indefinitely. Background Strategic overview After the declaration of war on Nazi Germany by Britain and France in the aftermath of the German invasion of Poland, nine months of stalemate took place along the Western Front. After the Polish Campaign, in October 1939, the planners of the Oberkommando der Luftwaffe (Luftwaffe High Command) and the Oberkommando der Wehrmacht (Supreme Command of the Armed Forces) turned their attentions to Western Europe. The German offensive—named Unternehmen