For want of a nail the shoe was lost

For want of a nail the kingdom was lost

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, Forwant of a rider the battle was lost, For want of a battle the kingdom was lost, And all for the want of a horse.

You have hit the nail on the head

If the shoe fits, wear it

A little neglect may breed mischief: for want of a nail the shoe was lost; for want of a shoe the horse was lost; and for want of a horse the rider was lost