Versailles certainly failed to keep the peace. Yet the problem was not because the treaty was too harsh, but because it was flawed from the start and never adequately enforced.
The Versailles Treaty was signed months after the armistice of November 1918, rather than after an utter collapse of the German Imperial Army. The exhausted Allies made the mistake of not demanding the unconditional surrender of the defeated German aggressor.
That error created the later German myth that its spent army was never really vanquished but had merely given up the offensive in enemy territory. Exhausted German soldiers abroad were supposedly “stabbed in the back” by Jews, Communists, and traitors to the rear.
The Allied victors combined the worst of both worlds. They had humiliated a defeated enemy with mostly empty condemnations while failing to enforce measures that would have prevented the rise of another aggressive Germany.
This is relevant today as some complain we caused Russian hostility after we won the Cold War. I find that charge ridiculous.
We were too easy on Russia in 1991. And Germany's contrast between 1919 and 1945 is instructive:
Again, the Germany that the victors were allegedly too harsh against after World War I revived to seek revenge while the Germany that the victors divided, de-Nazified, and forcibly made to join the victors [after World War II]--and which remains a democratic ally in the West to this day--worked, when the latter treatment was clearly far more harsh.
The West was far too easy on Russia 25 years ago. Mind you, Russia still had lots of nukes. So we couldn't press our advantage to post-World War II levels of crushing a defeated foe and remolding it in our image.
But the notion that the West was too harsh on Russia after the Cold War as a reason for Russian hostility is nonsense.
And now Russia is the sick angry man of Europe, bitter over paranoid tales of betrayal and hostility.
When you go to war, win the war if you have the option. Don't be shy. In the long run we'll all be happier and safer.