Below is an excerpt from a post that appeared at Samuraido.org. The full post may be read here.
For being one of
the main battlefield weapons of choice for Samurai and ashigaru
throughout the sengoku jidai, there are surprisingly few schools of
spearsmanship left today. In fact, there are only two that I know of:
Owari Kan-ryu and Hozoin-ryu, . There are other schools that have
tangential syllabus points related to the use of the spear, such as
Teshinshoden Katori Shinto-ryu, but these two are the only ones that I
know of which contain dedicated spear syllabus. With the knowledge of
this weapon thus spread thin, here are a few points which might help us
to better understand so-jutsu, the art of the spear.
- The weapon:
Yari come in a huge variety of shapes and sizes and reflected various
preferences and trends among the warrior classes over the years. Some
spears were also adapted for specific roles on the battlefield. The type
of spear that I use is called a sankaku yari. This means that the blade
has a triangular cross-section. This robust geometry means that such
spears are particularly suited to penetrating armour. The sankaku yari
had a different blade design from the su yari, or straight spear. The su
yari have two edges like a European spear, whereas the sankaku yari
possesses only a point. These simple designs of spear where commonly
favoured by warriors of all classes. For those who could afford it,
however, the addition of extra, angular blades or parrying bars greatly
increased the efficacy of the weapon, enabling the user to trap and
often disarm his opponent. These types of spear are very broadly called
kama yari, although there are a huge number of categories which clarify
the individual style of each spear head. Many

of
the schools of spear fighting had their own unique design of spear
which fitted their particular techniques. Hozoin-ryu favours a long
spear, generally around 2.8 metres in length with a horizontal parrying
bar near the base of the spear head to allow for the effective blocking
and trapping of other spears and weapons. Owari Kan
-ryu meanwhile, often use mobile, tubular grips on the hafts of their
spears, allowing greater power on the thrust by eliminating the friction
between the warriors hand and the shaft of the spear.
- The techniques for the warrior on foot:
Outside of koryu bujutsu, the nearest thing one can find to so-jutsu
is jukendo. The rifle and bayonet were, after all, intended to be
roughly analogous to the spear in their use and techniques. In both jukendo
and so-jutsu, there is generally only one attacking move, the straight
thrust. While this is the main killing technique of a spear armed
warrior, this does not take into account some of the rarer designs of
spear, or battlefield tactics that called for other techniques. The
kikuchi yari, for example, was a straight bladed spear that possessed
only one cutting edge, essentially a naginata and using many of the same
forms and techniques often involving wide, sweeping cuts, but with the
added bonus of a more effective thrust.
On the battlefield, soldiers could find themselves up against
two types of opposition: infantry and cavalry. Yari were often used by
samurai and ashigaru alike in formation whilst on foot and thus what an
opponent would normally be facing were a wall of spears. As a result the
aim of the individual soldier was to knock the opponent’s spear out of
the way either up or down (knocking sideways earned you no favours from
your comrades), making the kill, and then attempting to exploit the gap
in the enemy formation, perhaps ganging up with an ally on the next man
along. The main techniques in battlefield so-jutsu therefore are
knocking away the opponent’s spear, thrusting, and circling movements to
trap the opponent’s weapon.
Against cavalry the spearman faces a rather different problem, namely
a very large and heavy horse and rider bearing down on you at some
speed. If one were to try and meet the target head on in a standing
position, you would simply be knocked over by the sheer force of the
charge. The technique against horses was, therefore, for
the front rank of the spear formation to wait until the opposing
cavalry was utterly committed to the charge, then all take one pace to
the side and kneel down with their spears leveled at the horse’s chest
height. The back end of the spear was braced against the ground meaning
that the warrior would not take the full force of the impact. This move
would certainly have caused some spears to break, but with the momentum
of the charge destroyed, the downed riders and now disorganised
attacking force could be much more easily dealt with by the spear
wielding warriors.
Anyone who has ever done any work with polearms will know that the
secret to performing these techniques effectively and quickly lies in
the physics of moments. When I gave a student of mine a real yari to try
the other day, he immediately remarked that it was difficult to keep
the spear head up and facing his opponent. Admittedly my particular
spear has quite a substantial blade on it and it is also a modern
reproduction and therefore the tang is only about fifty centimeters
long, but even so, what was he expecting? It is after all a lump of
metal on the end of a stick. Moment = force x distance from the pivot so
of course, the weight of the spear head is going to be a little
difficult to manage. This is why it is so important in all spear
techniques that the rear hand is the one doing all of the work moving
the spear head, while the front hand acts like a guide and support. Try
it any other way, and you’re either going to have a very hard time
controlling the weapon, or you’re going to get tired incredibly quickly
just holding the thing.