Large naginata and kanabō were also popular in this period. However, infantry units gradually came to be equipped with yari (spears) in addition to naginata, and because ōdachi was disadvantageous for mountain battles and surprise attacks, and only a few powerful men could use it effectively, this trend ended for a short 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 yari and tanegashima (guns) by a large group of infantry, ōdachi became even more obsolete. As ōdachi became useless, it was often replaced with a tachi and katana. Even so, sengoku-daimyo in the Sengoku period dared to equip their own troops with ōdachi in order to show off their strength and bravery. Uesugi Kenshin had men more than six shaku (approx. ) tall equipped with an ōdachi guard around his horse. The Asakura clan made a troop called Rikishizei (力士勢) equip with an ōdachi with a blade length of 5 shaku (approx. ), and fought well against the troop of Oda Nobunaga in the Battle of Anegawa. The 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. According to the historical book Wakan Shuyo (), the had a blade length of 3 shaku (traditional Japanese feet) and 9 sun (traditional Japanese inches; totaling approx. ) and ōdachi had a blade length of 3 shaku 3 sun (approx. ), but in fact, they were not strictly distinguished between nodachi and ōdachi, and it is thought that the term ōdachi indicated a long tachi, and the term nodachi indicated an ōdachi used in field battles (in keeping with the name, since the initial literally means "field"). Production 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