This is, apparently, one of the most famous battles—in both history and film—from the big era of the samurai and the ronin. And it was basically a one-hit fight (it's mostly shouting until 3:30):

And here's the story:

Miyamoto Musashi and Sasaki Kojiro were almost destined to fight. Both were undefeated shuygosha whohad risen from obscurity. Sasaki used a very long katana called The Drying Pole, after the long poles used to dry laundry. Musashi used wooden swords, called bokken, usually used for training. Musashi went down to Kokura to fight Sasaki. After a short delay, they decided to fight at a small island of the coast. This place is now called Ganryu Island, after Sasaki’s full name, Ganryu Sasaki Kojiro.

Musashi was told to be there at the hour of the dragon. However, at this time, he was still asleep, and an official was sent to wake him as Sasaki and the judges waited in the hot sun. Finally, after a long time, Sasaki could see Musashi’s boat approaching.

Musashi knew Sasaki relied on his sword’s length as an advantage, so Musashi took an oar from the boat and carved it into a sword shape as his weapon, a foot longer than Sasaki’s sword. Musashi stepped down from the boat and slowly walked toward Sasaki. Sasaki became angry at Musashi for insulting him with his lateness, and threw his scabbard into the water. Musashi simply said,”You’ve lost Kojiro. Only the loser would have no need for his scabbard.” With this he rushed at Sasaki.

Sasaki swung his sword at Musashi, but Musashi dodged and struck him in the head with the wooden sword. Kojiro lay on the ground. Musashi walked over to him, and Sasaki suddenly slashed upwards at Musashi. Musashi quickly dodged and struck Sasaki in the ribs. Sasaki lost consciousness. Musashi checked Sasaki for signs of life, but there were none. Musashi bid the judges farewell and left in his boat.