To get an idea of the fighting techniques with the ôdachi, we have to make a detour via China of the late 16th century as hardly anything is known on this topic from the time this sword stlye emerged, i.e. the Nanbokuchô period. Japanese pirates (wakô, 倭寇, Chin. wokòu) were raiding the coastlines of China and Korea for almost three centuries from the Kamakura period onwards. There were of course several attempts to get a grip on this situation. One of the most successful Ming-dynasty military leaders appointed to deal with the wakô was general Qi Jìguang (戚継光, 1527-1588). In Eiroku four (永禄, 1561), Qi Jìguang captured from Japanese pirates a mokuroku catalogue (目録) of the Kage-ryû (影流) of swordsmanship, although there is some discussion about what such a document is doing on a pirate ship. Some say Aisu Hisatada (愛洲久忠, 1452-1538), the ancestor of the Kage-ryû was himself a pirate. There are namely records extant which show that Hisatada made it over to Ming-China as a young man. Others assume that Qi Jìguang bribed several pirates to bring him as much information on Japanese warfare as possible to be used by him against the wakô.
However, the data from this mokuroku was worked into Qi´s later 14-volume „Kikô-shinsho“ (紀効新書, Chin. „Jìxìao Xinshu“) from 1588. The first 18-volume edition from 1560 does not contain the mokuroku. Later the Ming-officer Máo Yúanyí (茅元儀, 1594-1640?) worked the „Kikô-shinsho“ in 1621 into his epic 240-volume standard work „Bubi-shi“ (武備志, Chin. „Wûbèi-zhì“). The „Bubi-shi“ in turn was reintroduced to Japan and republished, for example by Matsushita Kenrin (松下見林, 1637-1704) in Genroku one (元禄, 1688) in his work „Ishô-Nihon-den“ (異称日本伝). Via this way, the early mokuroku of the Kage-ryû was again in circulation in its native country. In the same year as Máo Yúanyí, i.e. in 1621, the Shaolin warrior-monk Chéng Zongyóu (程宗猷, 1561-?) published his „Tantô-hôsen“ (単刀法選, Chin. „Dandao-fâxûan“) in which he introduced 22 kata forms for using a Japanese sword (in a later edition, these kata were extended by two to altogether 24 forms).
Interesting is now first, that general Qi´s studies on Japanese swordsmanship based on the captured Kage-ryû mokuroku had a great influence on Chinese martial arts and artists, and second, that Chéng Zongyóu mentions in his „Tantô-hôsen“ that the kata for the ôdachi are meant to ward off attacks with the yari. Incidentally, the Chinese version of the ôdachi is called „cháng-dao“ (長刀, see picture 1). It is assumed that the cháng-dao was not just a copy of the Japanese ôdachi because very similar swords were used in China since earlier times as anti-cavalry swords (zhânmâ-dao, 斬馬刀). Another derivative of the overlong cháng-dao or zhânmâ-dao was the miáo-dao (苗刀), although this sword form appeared somewhat later. The entire mounting of the cháng-dao is strikingly similar to Japanese swords (see also pictures of the kata forms at the end of the article). That means they have wrapped hilts, narrow saya with kurigata, a habaki and a small and roundish tsuba. However, at the Chinese variant the hilt narrows somewhat down towards the tsuba and the tip also narrows down almost in shôbu-zukuri manner.
Picture 1: Two extant cháng-dao.
Chéng´s emphasis on a yari defence goes probably back to the 13th century when the Mongols invaded China. Back then the long spear turned out to be very effective for larger armies of foot soldiers. Thus some assume that the emergence of the ôdachi in Japan is connected to the Chinese experience when namely at the same time the so-called „kikuchi-yari“ (菊池槍) was introduced on the Japanese battlefield. Apart from that also the Japanese pirates made frequent use of the ôdachi. We know that from mainland chronicles which write that specialized men of their smaller units used it to break or just cut open doors or walls of houses with these oversized swords which were then ransacked. In picture 2 we see at least one pirate who is carrying a longer than usual sword. It is also said that the ôdachi were used to cut in half the long poles with which the people from the mainland tried to keep away the Japanese pirate boats. Picture 3 shows such a scene where wakô are fighting against Koreans, although they are wielding standard-length swords and one pirate even wields two swords of the same length.
Picture 2: Japanese pirates attacking a mansion.
Picture 3: Koreans trying to keep away Japanese pirates.
Let me recapitulate. Overlong swords were known and used in China since at least since the Han Dynasty (漢, 206 BC – 220 AD) as we find names like zhânmâ-dao in later records on that time. Later it gained again popularity when the Mongols attacked the Jin Dynasty (金, 1115-1234). The zhânmâ-dao and cháng-dao were namely used to attack horses and ward off and cut in half enemy yari. With the use of kikuchi-yari and the changes in warfare during the Nanbokuchô period, the ôdachi entered the stage of the Japanese battlefield whereas fighting with this kind of sword should become soon the strong point of the Kage-ryû. Connected or not remains to be seen but the Japanese pirates of the 16th century made also frequent use of the ôdachi. When general Qi captured a mokuroku catalogue of the Kage-ryû from Japanese pirates, he made the overlong sword again popular in his own country and used the new style of fencing against the raiders. On the other hand, the ôdachi was never used in larger scales in Japan, even with the changes in warfare and the focus on yari during the Muromachi period. It is assumed that this is directly connected to the quality standard and forging techniques of the nihontô. That means it was just too expensive and time consuming to equip larger troops with ôdachi. But with Qi´s capturing of the Kage-ryû mokuroku and the subsequent publications we have at least a small insight on the pre-Muromachi period swordsmanship using the ôdachi. That means there was definitely a certain training with this weapon and it was not just giving them to low-ranking foot soldiers so that they can swing them around in the hope to hit some horse´s legs. Apart from that we know several accounts of famous bushi using the ôdachi as main weapon and their heroic deeds with them. But I want to introduce these accounts on another occasion.
Below some kata depictions from the „Tantô-hôsen“.