A Horseshoe Nail???

I thought this was elementary prose, but I had a hard time tracking it down.  At any rate, please appreciate the inspiration -- our horseshoe dog!!!

For want of a nail the shoe was lost.


For want of a shoe the horse was lost.

For want of a horse the rider was lost.

For want of a rider the battle was lost.

For want of a battle the kingdom was lost.

And all for the want of a horseshoe nail.