counter for horsemen
Used to count mounted soldiers or riders, especially in historical or military contexts.
In the Warring States period, cavalry units of several thousand horsemen were formed.
He charged into the enemy camp alone on horseback.
The enemy army attacked with about three thousand horsemen.
人 is the general-purpose counter for people, while 騎 is reserved specifically for mounted riders such as cavalry.
匹 read き is an archaic way to count horses, whereas 騎 is the modern counter for mounted riders or cavalry.
頭 counts the horses themselves, while 騎 counts the riders mounted on them, so the two are easily mixed up when describing cavalry.
From the kanji 騎, meaning 'to ride' or 'horseman', used as a counter for mounted individuals.