On Wednesday, July 31 1940, Hitler authorized an all out attack on Britain. The stage was set for the biggest air battle in history. 2500 aircraft flying against the 650 fighters of the RAF. This documentary looks at the giant clash between two nations, examining how both countries used their resources during the Battle of Britain: from aircraft to air defense, and from intelligence to organization. As well as gaining analytic insight from veteran British fighter pilots, presenter James Holland travels to Germany where he meets some of the few surviving Battle of Britain Luftwaffe Aces and gains access to diaries offering further striking, firsthand testimony from those who fought in the battle.