Yet another alternative history question - just for fun.
What do we think would have been the realities of the European allies challenging Hitler instead of appeasing him, would it have made a difference?
If yes: how and why would it?
If no:why would it not?
Well, if the British and French had acted at the time of the reoccupation of the Rhineland in early 1936, or even shaken some sabres, Hitler’s confidence would have been severly shaken. It was the first signal that he wouldn’t be challenged, even with a weak military.
But it would have made the German generals happy - they always said that Germany wouldn’t be ready for a war until 1941/42.
So, Hitler would probably have gone to war but later, and possibly even better armed. For the British and French, the same. The British also needed extra time for their rearmament policy to take effect (again the British military stated they needed until 1941/42).
I doubt it would have made any difference to Germany starting the war, but it might have delayed it depending upon the nature and effect of the challenge.
I think the seeds were sown long before Hitler came to power by the Allies not preventing the build up of German armaments and forces from the early 1920’s onwards. Whether they could have done much to prevent it is a different issue.
The Allies also left the German army in its unique position in the German state and life, which allowed it unilaterally to ignore the provisions of the Versailles Treaty pretty much from the moment it was signed, thus laying strong foundations for Hitler to rapidly expand his military capacity after he came to power.
If the Allies had been prepared to go to war, as distinct from merely challenging Hitler in a diplomatic sense, and had started to mobilise it might have have changed things, but it would have had to be soon after Hitler came to power. By 1937-1938 the odds were increasingly on Hitler’s side if he fought only France, Britain, and Belgium.