Rear Guard

Rear guard – 1. the rearmost elements of an advancing or withdrawing force. It has the following functions: a. to protect the rear of a column from hostile forces; b. during the withdrawal, to delay the enemy; c. during the advance, to keep supply routes open. 2. Security detachment which a moving ground force details to the rear to keep it informed and covered.

Sources:

ААР-06 (2017) NATO glossary of terms and definitions (English and French), 2017.