The Japanese Oyumi
21st February 2006
Japanese writings alluded to a mysterious weapon called the Oyumi or Do. Inferring from the sizes and ranges of the projectiles thrown, the Oyumi is believed to be a large platform mounted siege-class crossbow as opposed to the Shu Do or handheld crossbow which the Japanese would have obviously been familiar with from their interactions with the Chinese mainland. The Oyumi was probably not a single standard type of giant crossbow but one which took on different configurations ranging from simple bolt shooters to stone throwers. Unfortunately for us, no illustration of the Oyumi had survived nor had any evidence turned up at archaeological sites leaving us to speculate on the form of this "great" Japanese siege crossbow and on how it would have operated.
The Oyumi enjoyed a long history in Japan with the earliest written reference recording an unspecified number of these mysterious devices being presented to the court in A.D. 618 by Korean envoys from Koryo. By the late 7th century, the Oyumi was well into general service, deployed under the Ritsuryou military system by provincial regiments as well as various guard units in the capital and lasted through to the early 10th century A.D.
The Oyumi however, must have been a fairly complicated machine to operate, setting it apart from the Shu Do or handheld crossbow. Throughout the 9th century A.D., between A.D. 814 and A.D. 901, the Japanese court was petitioned by a total of 17 provinces for Oyumi instructors as the Oyumi stored in their armouries were going to waste because they had no one who knew how to operate them.
In A.D. 835, Shimagi Fubito Makoto was credited with the invention of a new type of Oyumi (Shin Do) that could throw projectiles more easily than the existing design as well as being able to rotate and fire in all directions. When it was demonstrated, it was written that the assembled courtiers could:
The Oyumi was obviously a formidable machine of war because two years later in A.D. 837 we found the following in a petition to the court from Mutsu province:
Further evidence was found in the 10th century A.D. when Miyoshi Kiyoyuki, a court courtier wrote in a famous memorial to the Emperor Diago:
These generous descriptions notwithstanding, the Oyumi survived only as far as the 12th century A.D. when all mention of this weapon disappeared from Japanese records and Japan entered an era where all mention of catapults of any kind was glaringly missing, the Oyumi included, until the introduction of gunpowder cannons into Japanese battlefields.