Which term describes a force that works to protect another unit while it is engaging the enemy?

The term that accurately describes a force working to protect another unit while it is engaging the enemy is "covering force." This type of force is specifically designated to provide protection and cover for units that are actively engaged in combat, allowing them to focus on their primary mission without being overly concerned about enemy attacks from other directions.

Covering forces often engage the enemy to suppress their fire and create a safer operational space for the unit they are protecting. They play a crucial role in maintaining the safety of advancing or engaged units, typically operating in a manner that allows for maximum effectiveness while minimizing their exposure to enemy fire.

In contrast, while other terms like screening, guard, and supporting forces may relate somewhat to protective roles, they primarily focus on different tactical objectives. For instance, a screening force typically identifies and assesses enemy movements, a guard force often secures essential locations against threats, and a supporting force provides assistance in combat but does not specifically focus on protection during enemy engagement in the same way that a covering force does. Thus, the nuances in the definitions underline why covering force is the correct answer for the question posed.