Disclaimer: Tolkien saw it for himself - fortunately Kortirion comes to this wisdom second-hand.
Blades to plough - flails to harrow... what a harvest they made!
Lances staked like grim stooks of corn about the Pelennor, bones and bodies dragged, heavy as grain-sacks, either to grave or pyre. The grass lay mangled to mud and pulp, hay might be difficult to come by this year… but if cleared quickly there might still be the chance of a more natural harvest.
Then, reluctant warriors might change back to farmers, to farriers, shop-keepers and ostlers... even if regular men-at-arms must still heed their posts.
One battle might end a war, but did not totally destroy the evil.