|Place of origin||Japan|
|Used by||Samurai, Kendo, Iaido practitioners|
|Produced||Nanboku-chō period 14th century until present.|
|Mass||2.2 kg (4.9 lbs) to 14.5 kg|
|Blade length||approx. 90.9 cm (3 shaku) up to 377 cm (12.4 shaku)|
|Blade type||Curved, single-edged|
|Hilt type||Two-handed swept, with circular or squared guard. Material: wood, metal, ivory , fish skin, silk|
The ōdachi (大太刀) (large/great sword) or nodachi (野太刀, field sword) is a type of traditionally made Japanese sword (日本刀, nihontō) used by the samurai class of feudal Japan. The Chinese equivalent of this type of sword in terms of weight and length is the miao dao, and the Western battlefield equivalent (though less similar) is the longsword or claymore.
The character for ō (大) means "big" or "great". The dachi here (太刀) is the same as tachi (太刀, lit. "great sword"), the older style of sword/mounts that predate the katana. The chi is also the same character as katana (刀) and the tō in nihontō (日本刀 "Japanese sword"), originally from the Chinese character for a blade, dāo.
To qualify as an ōdachi, the sword in question would have a blade length of around 3 shaku (90.9 centimetres (35.8 in)). However, as with most terms in Japanese sword arts, there is no exact definition of the size of an ōdachi.
In the Nanboku-chō period in the 14th century, huge Japanese swords such as ōdachi became popular. The reason for this is thought to be that the conditions for making a practical large-sized sword were established due to the nationwide spread of strong and sharp swords of the Sōshū school. In the case of ōdachi whose blade was 150 cm long, it was impossible to draw a sword from the scabbard on the waist, so people carried it on their back or had their servants carry it. Large naginata and kanabō were also popular in this period. However, as infantry were equipped with yari and naginata, this fashion died out in a short period of time. Furthermore, from the Sengoku period in the latter part of the Muromachi period to the Azuchi-Momoyama period, as tactics shifted to fighting with yaris and guns by a large group of infantry, ōdachi became even more obsolete. As ōdachi became useless, it was often cut and replaced with a tachi and katana.
Ōdachi was used as a weapon, but because of its magnificent appearance, it was often used as an offering to kami, a Shinto shrine. For example, Ōyamazumi Shrine, which is said to be a treasure house of Japanese swords and armor, is dedicated to the national treasure Ōdachi, which was dedicated by Emperor Go-Murakami, and ōdachi, which was dedicated by Ōmori Naoharu and killed Kusunoki Masashige.
In the peaceful Edo period, ōdachi was no longer regarded as a practical weapon and came to be recognized only as an offering to the kami of Shinto shrines.
Ōdachi are difficult to produce because their length makes traditional heat treatment more complicated: The longer a blade is, the more difficult (and expensive) it is to heat the whole blade to a homogeneous temperature, both for annealing and to reach the hardening temperature. The quenching process then needs a bigger quenching medium because uneven quenching might lead to warping the blade.
The method of polishing is also different. Because of their size, ōdachi are usually hung from the ceiling or placed in a stationary position to be polished, unlike normal swords which are moved over polishing stones.
Method of use
As battlefield weapons, ōdachi were too long for samurai to carry on their waists like normal swords. There were two main methods in which they could be carried. One was to carry it on one's back; however, this was seen as impractical as it was impossible for the wielder to draw it quickly. The other method was simply to carry the sheathed ōdachi by hand. The trend during the Muromachi era was for the samurai carrying the ōdachi to have a follower to help draw it.
An exception does exist, though. The Kōden Enshin-ryū taught by Fumon Tanaka use a special drawing technique for "short" ōdachi allowing it to be carried on the waist. The technique is to pull out the sheath rather than drawing the blade. While this move is also used in other schools, for example, Yagyū Shinkage-ryū, and Iaidō, only Enshin-ryū seems to have used it to improve the drawing speed of an ōdachi, the other schools having used it with classical katana. The Kage-ryū style is also used to draw from the belt, using blades of approximately 2.8 shaku.
Ōdachi swordplay styles differed from that of other Japanese swords, focusing on downward cuts.
One possible use of ōdachi is as large anti-cavalry weapons, to strike down the horse as it approaches. Alternatively, it could be used as a cavalry-on-cavalry weapon comparable to the Chinese zhanmadao, with the long reach, increased weight and slashing area of the blade offering some advantages over spears, lances and smaller swords.
The longest known ōdachi is the Odachi Norimitsu with a total length of 377 centimetres (148 in). It was forged by the Japanese master bladesmith Norimitsu Osafune in the former Bishū province in August 1446. It is kept in the Kibitsu Shrine in Okayama. A special attribute is that this blade was forged from one piece, similarly to the conventional Japanese katana; it was not forged from multiple pieces or sections. This required the skill of a master bladesmith. The blade, hada and hamon are authentic. This odachi has a bo-hi (fuller or colloquially, but inappropriately "blood groove"). Norimitsu was a famous line of swordsmiths that began in the Oei Bizen school (1394) and continued until the end of Bizen. Around 2000s it was polished and named "Kibitsu maru" by the priest of Kibitsu Shrine in Okayama Prefecture.
These are the specifications of the Ōdachi Norimitsu.
- Total length: 377 centimetres (148 in)
- Nagasa (cutting edge): 226.7 centimetres (89.3 in)
- Sori (curvature): 5 centimetres (2.0 in)
- Nakago (tang): 151 centimetres (59 in)
- Blade thickness (maximum): 2.34 centimetres (0.92 in)
- Habaki ((collar to hold blade in scabbard): 5.85 centimetres (2.30 in)
- Weight: 14.5 kilograms (32 lb)
- Mei (blade signature, 銘): Bishu Osafune Norimitsu (備州)
- Location: Kibitsu Shrine, Okayama.
- Production date: August 1446 (Muromachi period)
- Sugata (blade shape): Shinogi-zukuri, maru-mune, bo-hi with maru-dome
- Hada (grain pattern, 肌): Itame
- Hamon (temper pattern): Ko-gunome, choji with tobiyaki and kinsuji.
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