Tachi

A tachi (^?) was a type of traditionally made Japanese sword worn by the samurai class of feudal Japan. The tachi style of swords preceded the development of the katana—the first use of the word katana to indicate a blade different from tachi appears toward the end of the twelfth century.

Chokutō, straight swords, were also called tachi, but written as 大刀.

The production of swords in Japan is divided into specific time periods:

Authentic tachi were forged during the Kotō period, before 1596. With a few exceptions, katana and tachi can be distinguished from each other if signed by the location of the signature (mei) on the tang. In general the signature should be carved into the side of the tang that would face outward when the sword was worn on the wielder's left waist. Since a tachi was worn cutting edge down, and the katana was worn cutting edge up the mei would be in opposite locations on the tang of both types of swords.

An authentic tachi that was manufactured in the correct time period averaged 70–80 centimeters (27 9/16 - 31 1/2 inches) in cutting edge length (nagasa) and compared to a katana was generally lighter in weight in proportion to its length, had a greater taper from hilt to point, was more curved with a smaller point area.

Unlike the traditional manner of wearing the katana, the tachi was worn hung from the belt with the cutting-edge down, and was most effective when used by cavalry. Deviations from the average length of tachi have the prefixes ko- for "short" and ō- for "great, large" attached. For instance, tachi that were shōtō and closer in size to a wakizashi were called kodachi. The longest tachi (considered a 15th-century ōdachi) in existence is more than 3.7 metres (12 ft) in total length with a 2.2 metres (7 ft 3 in) blade, but believed to be ceremonial. In the late 1500s and early 1600s many old surviving tachi blades were converted into katana by having their original tangs cut (o-suriage), the signature would be lost in this process.

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