Which term describes a force that fights to gain time while protecting the main body?

The term that best describes a force that fights to gain time while protecting the main body is "guard." A guarding force is specifically tasked with delaying enemy forces to allow the main body time to prepare, reposition, or carry out other operations. This typically involves engaging in defensive actions to prevent an enemy from advancing or to disrupt their plans while ensuring that the main force can operate with reduced threat.

In a military context, a guard force often positions itself at advantageous locations to observe the enemy, maintain contact, and provide early warnings while also engaging them to slow their progress. This strategy is crucial in maintaining the effectiveness and safety of the main body during an operation.

The other terms are defined differently: "support" refers to providing assistance or backup to another unit, "occupy" indicates taking control or holding a specific area, and "interdict" involves actions taken to prevent an enemy's movement or resupply. Each of these terms has distinct applications and does not encapsulate the specific role of delaying actions while protecting a main force like a guard does.