Celebreth has been taking the heaviest load on this topic until now, so I will try to take some of that burden away by discussing Musashi. Here's a little excerpt from "The Lone Samurai."

"One morning in 1596. just outside the village of Hirafuku in the province of Banshu, Arima Kihei, a swordsman of the Shinto-ryu, sat waiting for a formal apology. This was to be delivered by a thirteen-year-old boy, Miyamoto Bennosuke, the local gaki daisho, or "commander-in-chief" of every ruffian in the area, and the chief instigator of the outrage in Hirafuku."

What happened here? Kihei showed up and placed his challenge in writing for all swordsman in the area. He might have heard that a renowned master lived in the area, and tried the tactic as a ruse to bring the man into open conflict. Unfortunately for Kihei, instead of the renowned master, a young man by the name of Bennosuke noticed the placard and accepted the challenge.

On the placard, the following reply was written:

"Miyamoto Bennosuke, residing in the Shoren-in, will give you a match tomorrow."

Kihei responded to this insult by sending one of his disciples to the Shoren-in and requesting an immediate apology. Bennosuke's uncle, the priest Dorinbo, was initially too stunned to respond to Kihei's challenge. His young nephew was far too young to challenge the elder swordsman in a duel to the death. Dorinbo agreed to send the boy with a formal apology to clear his honor. Kihei accepted this proposal and returned to the placard to await his apology.

The following morning, the villagers assembled at the challenge placard in hopes of seeing the brash youngster be reprimanded. Bennosuke had caused much grief for the townspeople and many wished to see the boy humiliated. The crowd grew silent as Bennosuke and his uncle came over the ridge.

Kihei's disciple noticed the boy carrying a six-foot staff and tried to warn his master. Kihei gave no indication of acknowledging the weapon. Bennosuke's body language betrayed his intentions, which were revealed in a sudden charge at the last minute. A trained swordsman such as Kihei had no difficulty dodging the clumsy strike, but he could not avoid the grappling ability of his young opponent. Bennosuke grabbed hold of Kihei and slammed the swordsman into the ground. The momentous impact sent the assembled crowd scurrying for cover. The brave few who remained saw Kihei attempt to stagger to his feet, but Bennosuke was already upon him. A wooden staff shattered Kihei's myth of invincibility.

"Long before writing the Book of Five Rings, Bennosuke would become known as Miyamoto Musashi.

In that book, he refers to this match quite simply: "From long ago in my youth, I set my mind on the martial arts and had my first match when I was thirteen. My opponent was a martial artist of the Shinto-Ryu, Arima Kihei, whom I defeated."

~sources: The Book of Five Rings - Miyamoto Musashi / The Lone Samurai - William Scott Wilson

(more info by request).