Which of the following is an example of an enabling force?

An enabling force refers to actions or elements that enhance the effectiveness of a primary operation or facilitate a mission's success. Among the provided options, assault is an example of an enabling force because it actively engages the enemy and creates opportunities for follow-on operations. This engagement can serve to disrupt enemy defenses, allowing for subsequent maneuvers and support actions to be executed more effectively.

In contrast, flanking typically involves a maneuver strategy rather than being categorized directly as an enabling force; it is more about the method of engagement. Retreat refers to a withdrawal from a position and does not actively contribute to enabling a mission but rather constitutes a change in strategy. Surveillance, while crucial for gathering intelligence, supports operations and provides necessary information but does not directly engage in a mission as an enabling force would. Therefore, assault stands out as the action that enhances operational capabilities.