Hōseki (抛石) - Japanese Catapult

Hōseki (抛石) - Japanese Catapult

A Sijiao taken from Wujing Zongyao (武經總要). Due to the lack of Japanese iconography on the subject, I've used a Chinese ones which very likely resembled the Japanese version.

Another very obscure and overlooked Japanese weapon is the catapult, also known as mangonel. In Japanese it is called Hōseki, Tōsekiki (投石機), or Hatsuishiki (発石木) and Hihō (飛砲) in historical texts.

There are many reasons why this type of weapon is hardly associated with Japanese warfare, but before addressing this fact, it is worth to look at the weapon itself and its history.

The first mentions of stone projectiles being used to inflict damage is found inside the Nihon Shoki and we can read that these projectiles were fired by large siege crossbows called Ōyumi (大弓).

Nothing is really known about these devices although the academic consensus on the matter is that they weren't catapults-like machines.

The first references to proper catapults used in Japanese warfare are found in the Taiheiki of the 14th century; Kusunoki Masahige used one while besieged by Aso Harutoki's army in 1333 although no description for the weapon exist. This device was likely used as an antipersonnel weapon. In the Taiheiki, these catapults are compared to Chinese ones.

The true first complete description of a catapult used in Japan is dated 1468 during the Ōnin war. In this case, a traction trabuchet was uses and it is described in the Hekizan Nichiroku.Such weapon was made by a specialized craftsmen from the Yamato provinces and resembled a Chinese "Crouching Tiger Trebuchet" and it was used to throw 3 kg stones or explosive bombs known as thunder crash bombs (震天雷) as far as 274-300 meters. 

These projectiles shattered on impact and they were used against enemy formations or to destroy light small towers and to set fire to other facilities in Kyoto during the conflict.
Each catapult was operated by a crew of 40 men who were the ones that made the arm of the device throwing the projectiles; the weapon was rater small and compact, capable of being used in small spaces compared to larger and heavier catapults. Unlike a counterweight trabuchet, it was operated by manpower rather than a heavy weight. This decreased the power of the weapon but it also allowed a greater "rate of fire".

An artistic representation of a Japanese catapult used during the Ōnin war.

Other accounts of these catapults being used exist as well during the Sengoku period. During the siege of Takigawa in 1552, the Mori used these weapons to inflict casualties on the opposite side to a greater effect; in fact, up to 25% of the wounds inflicted by ranged weapons were caused by traction trebuchets according to the documents of that battle.
Another instance in which catapults were used was during the siege of Omori in 1599; in this case, the weapon was operated by women and children since the defenders were a peasants army. A final references to this weapon being used was the Osaka siege, where the defenders used the famous fire projecting mangonels to launch incendiary and explosive bombs on the attackers.


While said weapon was clearly known and used during the Samurai period, and in some cases inflicted a good amount of casualties on the receiving side, it is quite evident that catapults in Japan were rare and saw little usage.
This is quite easy to explain; unlike its Chinese or European counterpart, the Japanese catapult was not particularly heavy or strong in its power, and was used mainly as a form of antipersonnel weapon rather than to destroy walls and open breeches against castles or city walls.

This is due to the location of Japanese castles; the majority of these fortifications were already located on strategic places such as high hills or mountains peak which prevented the offenders to effectively use catapults and this is why heavy counterweight trabuchets were never developed, because they would have been useless in this particular scenario. In fact, as I have already written in other instances, Japanese terrain is heavily mountainous.In addition to that, when hirajiro (平城 - located on open plains) castles were developed and started to spread all over Japan, although they could have potentially been attacked by catapults, cannons started to be the main artillery weapons.

Azuchi castle, a typical yamajiro (山城) located on top of a very high hill. Such fortifications would have been impossible to attack with a trabuchet.

So the main role of this weapon was indeed to create mayhem inside enemy formations. However, despite its effectiveness in doing so, they required specialized artisans and a good amount of resources to be made and operated. They were also very hard to move and were usually built on the spot.
All these features made the catapults quite costly and demanding for their effectiveness, so the warlords of the 15th and 16th century Japan preferred to invest their resources into massed archery and later on massed volley fire which were much more effective and required less efforts as well as being able of being deployed everywhere.
These are the main reasons why catapults saw very little usage in Japan.



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Gunbai.