THE 78th commemoration of the Battle of Britain celebrates the defence of the United Kingdom by the RAF against the Nazi air force, known as the Lutftwaffe, in World War Two. But what exactly happened in 1940 and how is it being marked. Here's all you need to know. The annual Battle of Britain Day is celebrated on September 15. The day is dedicated to the large-scale aerial battle that took place from July 10 until October 31, 1940. The clash was said to be the first major military campaign fought entirely by air forces. Britain's Royal Air Force defended...