Japanese Tachi Arms System

Timeline

1. c. 1300–1400Kyoto · KyotoThe Muromachi shogunate consolidated the tachi's status as the samurai's formal sidearm through its warrior status order. Standards for blade patterns, signatures, and koshirae (mountings) gradually took shape; swordsmith schools such as Bizen and Mino carried on the Kamakura forging tradition, and the tachi became a unified symbol of status, service, and the principal battlefield weapon.
2. c. 1400–1550Provinces of the Tōkaidō · TōkaidōAfter the Ōnin War, regional battles became frequent, and the ōdachi, as an oversized slashing weapon, was used among infantry and ashigaru ranks for armor-breaking, unhorsing horses, and psychological intimidation. Wielders often needed attendants to help draw the blade; tactically it was mixed with naginata and bows, forming the typical Sengoku combined cold-weapon formations.
3. c. 1550–1600Kyushu · KyushuAfter Portuguese matchlocks reached Japan via Tanegashima, Sengoku daimyo generally organized teppō units, and dense volley fire compressed the space for ōdachi charges. The tachi transitioned to the uchigatana (worn edge-up), while the ōdachi retreated to ceremonial use, shrine dedications, and displays of smithing skill, completing the arms system's transition to the early modern era.