Churchill was first and foremost a politician accustomed to making political points.  There is an almost top heavy analysis of Battle of Britain WW2 opinion underpinned by scholarship and research and offered by such luminaries as Holland, Bungay, Bishop and Roberts, so  as to make a very convincing case for the strategically decisive nature of this most crucial battle of WW2.    

The result of WW1 came about as a consequence of the British Army offensive of August 1918 and the subsequent destruction of the Hindenburg Line.   The French Army was in mutiny and the Americans had had little time to make their battlefield presence felt.