The Behemoth was destroyed. Cursed, Smashed and consumed by the Void. The only thing left behind to remind the world of its existence is now the fear of it in those who were left at the end. Of course they were grateful it was gone. All that metal, the terrible promise of order and strength at all costs. Their Knowledge of it will carry into the new world where soon a scary story will be told to a child. “One of the Behemoths Iron men will come to get you if you don't eat up your vegetables!”
Then it is just a matter of time. The thought in a child's mind to be repeated generation after generation until somebody thinks the best way to defeat their enemies is to build a Behemoth. Then it will rise again and hold the new world in its fist of steel, crushing everything until all that remains is the perfect will of Iron. . .