[Graham Boak]

You really believe that without the front-line troops of the Soviet Army, Hitler would never have started the war?

I can only presume that you are referring to the Nazi-Soviet pact and the joint invasion of Poland, but that only draws a specific line in history. To suggest that Hitler had not already started warfare in Europe ignores his actions in Austria and Czechoslovakia, or his plans for later, elsewhere.

Had Poland agreed to the passage of Soviet troops, the Munich agreement and the betrayal of Czechoslovakia may never have happened. Perhaps then Hitler's ambitions could have been curbed, but after that failure the war was inevitable. It was the failure of the "West" here that encouraged Stalin to come to his agreement with the Nazis, which no one on any side expected to last.