For want of a nail

"For want of a nail" is a proverb, having numerous variations over several centuries, reminding that seemingly unimportant acts or omissions can have grave and unforeseen consequences through a domino effect.

Poet George Herbert recorded it in 1640 as "For want of a naile the shoe is lost, for want of a shoe the horse is lost, for want of a horse the rider is lost." A longer version noted by Benjamin Franklin in 1758 runs:

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,
being overtaken and slain by the enemy,
all for want of care about a horse-shoe nail.