When is an area defense typically used by the enemy?

An area defense is typically employed by an enemy when the objective is to deny key areas to an advancing force or to maintain control over vital terrain. This type of defense strategy involves preparing defensive positions and utilizing available resources to effectively fortify certain locations. By focusing on controlling specific areas, the enemy aims to disrupt the movements of opposing forces and protect strategic assets such as supply lines, critical infrastructure, or logistical hubs.

In this context, the other options do not align as closely with the primary intention of an area defense. Gathering intelligence usually involves reconnaissance rather than a defensive posture. A surprise attack is more aligned with offensive tactics rather than a defensive strategy. Lastly, assisting retreating forces generally falls under a different type of maneuver, where the emphasis is on a withdrawal rather than holding specific ground.