The King of France marches twenty thousand men up a hill and, in true nonsense-rhyme fashion, never manages to go up again. The joke is the anticlimax, much like the Grand Old Duke of York.
From Mother Goose / Nursery Rhymes (traditional). See the whole collection.
The King of France went up the hill,
With twenty thousand men;
The King of France came down the hill,
And ne'er went up again.
About this rhyme
Text matches: King of France, twenty thousand men, up the hill and down again, never up again. · This rhyme is a documented relative/earlier form of the same up-the-hill-for-nothing joke used in 'The Grand Old Duke of York.'
Twenty thousand men march up a hill and immediately march down again, for no reason given and none needed. It's the same joke that powers The Grand Old Duke of York, pointless effort played completely straight. Say it briskly, like a drill sergeant, and let the flat ending land.
Public domain. Text from The Real Mother Goose (Blanche Fisher Wright, 1916), via Project Gutenberg. View the source edition