Which situation can prompt a commander to transition from offense to defense?

Transitioning from offense to defense is commonly prompted by reaching a culminating point. This state signifies that an offensive operation has maximized its effectiveness and is now at risk of overextension or attrition, making it necessary to shift to a defensive posture. At this juncture, a commander may determine that further offensive actions could lead to diminishing returns, increased vulnerability, or a higher likelihood of failure against the enemy's capabilities.

In contrast, a surprise attack might require a defensive posture but does not inherently dictate a shift from offense as it could also provide an opportunity to regroup and counterattack. Declining morale can certainly impact the effectiveness of troops and might lead to a defensive stance, but it is not a formal trigger for transitioning from offense to defense. An enemy retreat typically indicates the success of offensive operations, allowing commanders to exploit the situation further rather than shift back to defense. Thus, the culmination point represents a critical juncture, making it the most compelling reason for the transition in operational posture.