harquebuse

五輪書 "The Book of Five Rings and Other Works" のThe Fire Scroll(火の巻)から引用します。

About "Trampling the Sword"
"Trampling the Sword" is exclusive to combat.
In the case of large scale strategy, the enemy will start by shooting their bows or harquebuses. It will be difficult to penetrate the enemy line if you attack after they release a volley of arrows and bullets as they will have time to re-draw thier arrows and load powder in their barrels.

"harquebuses" は余り英語らしくありませんが、何かの飛び道具の様です。　辞書を見ます。

・Collins Dictionary: any of several small-caliber long guns operated by a matchlock or wheel-lock mechanism, dating from about 1400
Also: harquebuse, harquebuss, arquebus. Also called: hackbut, hagbut
・Wikipedia: An arquebus is a form of long gun that appeared in Europe and the Ottoman Empire during the 15th century. An infantryman armed with an arquebus is called an arquebusier.
The term arquebus is derived from the Dutch word haakbus ("hook gun") which was applied to an assortment of firearms from the 15th to 17th centuries.

スペルも色々あるようで、"harquebus"　はフランス語経由と書かれていたり、14世紀から使われていると書かれているのもありました。日本語で言う火縄銃だと思えば良さそうで、火縄銃はその機構から "matchlock gun" とも言われるようです。