noun
rear guard; rear guard unit
Military term for the unit or force that protects the rear of a formation, especially during a retreat. Also used metaphorically for the last or trailing element in a group.
See also: 殿軍
殿部隊は敵の追撃を食い止めながら撤退した。
The rear guard unit retreated while holding off the enemy's pursuit.
彼はマラソンで殿部隊を走っている。
He is running at the back of the pack in the marathon.