battle of britain

Those of you who are in the right place to see it, they are assembling at Goodwood (and then flying on to London ?), are lucky. http://www.bbc.co.uk/news/uk-34250794

I'm on a bit of a history kick again, plus some alternate history, and this question occurred to me. What was the decisive, game changing, battle of the war? Or was there one at all? The usual suggestions are: Britain, Midway, Kursk, Stalingrad, Normandy and the Ardennes. But were any of them...