Operation Sea Lion, the intended but never carried out amphibious landing on the British Isles, was one of the great strategic errors of the Third Reich. The lack of interest of the German General Staff was compounded by an endless series of failures by its intelligence services, while the British benefited from having managed to decipher the Enigma code. In reality, Hitler was very wary of facing the British and this led him to not accept Ridder's plan to invade the United Kingdom in early July 1940, giving rise to the Battle of Britain, one of the crucial moments of the Second World War.