Which term refers to an action that draws the attention of an enemy away from a principal operation?

The term that refers to an action designed to draw the attention of an enemy away from a principal operation is "Diversion." In military tactics, a diversion is employed to mislead the enemy, redirecting their focus and potentially exposing them to a more vulnerable state or facilitating the success of another operation.

This tactic can be critical in ensuring the effectiveness of a main effort by creating confusion within enemy ranks, thus allowing friendly forces to maneuver or to achieve their objectives with less resistance. The successful execution of a diversion can significantly impact the outcome of military engagements by ensuring that the enemy is preoccupied or misled about the true intentions of friendly forces.

In contrast, the other terms have distinct meanings: "Deceive" relates to misleading the enemy, but it's not specifically about diverting their attention; "Defeat" refers to overcoming or defeating the enemy forces outright; and "Delay" involves slowing down the enemy's movement or capabilities rather than redirecting their attention entirely. Each of these terms plays a role in military strategy but does not capture the full essence of diverting attention away from a principal operation like "Diversion" does.