For want of a nail...
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.
So back in 7th grade, my science teacher once sent me to the shop teacher to retrieve a nail. He handed me a note that read something like "As Richard III once said, "For want of a nail...". The shop teacher, who unlike the classic stereotype, was very well-read (he was the first teacher I ever had with a PhD), thought this was hilarious, and gave me the nail, with his compliments.
I never got the joke. Until today.
From http://en.wikipedia.org/wiki/For_Want_of_a_Nail_%28proverb%29
The earliest reference to the full proverb may refer to death of Richard III of England at the Battle of Bosworth Field. This short variation of the proverb (shown to the right), was published in "Fifty Famous People" by Richard Baldwin on page 26. The story associated with the proverb, describing the unhorsing of King Richard during battle would place the proverb's origin after the Battle of Bosworth on 22 August 1485. It should be noted that historically Richard's horse was merely mired in the mud[7]. In the story, the proverb and its reference to losing a horse is directly linked to King Richard famously shouting "A Horse! A Horse! My Kingdom for a Horse!", as depcited in Act V, Scene 4[8] from the Shakespeare play Richard III, which was written circa 1591. It's interesting to note that Kings are often considered Knights as well, which links the "Knight" variation to this story, and it also explains the "kingdom" reference prevalent in many of the variations. Note the similarities of the french quote below by Jean Molinet, which is contemporary with this event. Even the later Franklin vatriations (shown at right) - printed during conflict between England and America, when American culture and politics were shedding any reference to Kings and England[9] - would have the references to a King stripped out of a popular proverb, further circumstantially enforcing the argument that this story is the source of the original proverb. Either year - 1485 for King Richards death or 1591 for the Shakespeare play - the combined events in the story from "Fifty Famous People" plus the inclusion of the full proverb predate any other reference to a full causal chain of events; nail - shoe - horse - followed by at least one other dependent loss (i.e. rider, knight, battle, kingdom).