casualty; personnel loss
Military or organizational term for personnel lost through death, injury, capture, or desertion.
The battalion suffered many casualties in that battle.
死傷者 specifically refers to the dead and wounded, while 損耗人員 is a broader military term covering all personnel losses including capture and desertion.
Compound of 損耗 (loss, attrition) and 人員 (personnel, number of people).