cavalry; cavalryman; trooper
Refers to mounted soldiers or the military unit as a whole. In modern contexts, often historical or used in military terminology.
Cavalry played an important role in medieval battles.
He went to the battlefield as a cavalryman.
A hundred cavalrymen headed toward the castle.
At dawn, the cavalry charged into the enemy lines.
The general personally led the cavalry into battle.
Both 砲兵 and 騎兵 end in 兵 and name military branches, but 砲兵 is artillery while 騎兵 is cavalry.
Compound of 騎 (ki, 'riding' or 'horseback') and 兵 (hei, 'soldier'). The kanji directly convey the meaning of mounted soldier.