"You simply cannot say if X did not happen then Y would not have either in a situation so complex."

WTF???

If Chamberlain and the French had not "negotiated" with Hitler in 1938 then that would have been when Hitler got the war he wanted in the West bang on when the German General Staff had told him he should have it - there would not have been peace, that was not what Hitler wanted.

That is NOT saying "if X did not happen then Y would not have either" that is saying "if X did not happen then Y would have".

If Chamberlain and the French had not "negotiated" with Hitler in 1938 and the war had begun in 1938 France would have been overrun and Great Britain would have been defeated in the air and forced to accept German peace terms - because in 1938 Great Britain was simply not prepared for, or equipped to fight a war.

There is not an historian who knows anything about the period or a military expert who specialises in the Second World War who would disagree with anything I have stated. Again it does not come down to saying "if X did not happen then Y would not have either" it is a case of saying via logic and reason that "if X did not happen then Y would most certainly have happened". Hitler could not have cared a toss about the West, alliances forced him to focus on the West because those alliances interfered with his plans in the East - He'd mentioned them in his book in 1923.