The Battle of Britain is the name given to the Second World War air campaign waged by the German Air Force (Luftwaffe) against the United Kingdom during the summer and autumn of 1940. The Battle of Britain was the first major campaign to be fought entirely by air forces, and was also the largest and most sustained aerial bombing campaign to that date. By preventing Germany from gaining air superiority, the British forced Adolf Hitler to postpone and eventually cancel Operation Sea Lion, a planned amphibious and airborne invasion of Britain. However, Germany continued bombing operations on Britain, known as The Blitz. The failure of Nazi Germany to achieve its objective of destroying Britain's air defences in order to force Britain to negotiate an armistice is considered by historians to be its first major defeat in World War II and a crucial turning point in the conflict.