Miyamoto Musashi's two-sword style

Inspiration for using two swords

There are many theories about how Musashi came to use two swords in his style. His father, Munisai, was a master of various martial arts, including the use of jitte. It is believed that he taught Musashi various combat styles, so Musashi's first impressions on the martial arts as a boy must have come from his father's teachings. One way to use the jitte in combat was to pair it with a long sword, and use it to parry the enemy's attack, then strike him with the sword. This theory is endorsed by a story found in the Tanji hokin hikki manuscript, that describes how Musashi left his home after an argument with his father. He criticized his father's jitte technique, and Munisai, in anger, threw a dagger, then his short sword at him, upon which Musashi dodged both weapons and fled the house. This story can also serve as a basis for one theory which holds that throwing the short sword like a shuriken was one of the techniques that Musashi taught later in his Niten Ichi-ryū style.

Another possible inspiration is believed to be the drumstick movement of taiko. As a child, Musashi had the chance to observe the rhythmic movement of the two drumsticks at the Aramaki, or Sanomo shrine, a shinto shrine in the Miyamoto village.

Without ignoring how these experiences must have influenced Musashi in using two swords, I consider his combat experience as the primary factor for his choice of dual wielding weapons. The historical records of many of his duels, including his most famous one, against Sasaki Kojirō, describe him using a single sword. But in The Ground Book section of his treatise, Musashi advocates the use of the long and short sword for fighting against a large number of enemies:

                        It is better to use two swords rather than one when you are fighting a crowd,                                        and especially if you want to take a prisoner.

He also explains about the best use of the short sword, according to the environment:

                      The best use of the companion sword is in a confined space, or when you are                                         engaged closely with an opponent.

These statements hint at the fact that the effective use of the two swords has been tested through his own experience from his many duels. He found the use of two swords beneficial in various circumstances, as dictated by the environment or number of opponents.

Duels where Musashi fought with two swords

Although few, there are descriptions about some of Musashi's duels where he used two swords. One such duel was against Shishido, a master of the kusarigama. During the fight, Shishido arrested Musashi's sword with the chain, but then Musashi threw his wakizashi and killed him. From this story it can be surmised that Musashi was indeed adept at throwing weapons.

Another duel was the one against Miyake Gunbei, when Musashi used two wooden swords, one long and one short. He restrained Gunbei's sword by combining his two swords into a gassho position,  and kept him in check, before eventually winning by parrying one of his blows with the short sword in his left hand and stabbing Gunbei on the cheek with the sword in his right hand.

This way of fighting by using the two swords like a scissors against the opponent's sword was also mentioned in the description of a match held at Tokugawa Yoshinao's request, when Musashi demonstrated his style by fighting against a swordsman from the Owari clan, and nullified all his attacks with his two swords, while leading him in circles around the dojo and not initiating any offensive action himself.

And yet another use of two swords in a match was against lord Matsudaira Izumo no kami Naomasa, who wanted to test how effective Musashi's style really is, and also had to admit defeat against him.

Two swords in the Yagyū Shinkage-ryū techniques

It is interesting to observe the fact that in the Illustrated Catalog of the Shinkage-ryū Martial Arts, there are some techniques that deal with opponents wielding two swords: the korandome (opponent has a short sword in his left hand a long sword in his right hand), and the subete koran uchimonodome (opponent holds a long sword in his left hand and a short one in his right hand).

 So, even though Musashi was the most famous practitioner and founder of a two sword style, another kenjutsu school also recognized the need to know how to fight against an enemy that is wielding two swords.

Source(s):
The Lone Samurai: The Life of Miyamoto Musashi
The Book of Five Rings
The Life-Giving Sword: Secret Teachings from the House of the Shogun