What is the key instruction in General Order 11 regarding nighttime duties?

General Order 11 specifically instructs service members on the responsibilities and behavior expected during nighttime duties. One of the primary objectives of this order is to ensure the security and safety of the area being guarded. Challenging all persons on or near the post is vital because it serves as a measure to identify potential threats and maintain an awareness of who is present in a secured area. By actively challenging individuals, a Marine is contributing to a state of vigilance and enhancing the overall security posture, which is paramount during nighttime when visibility and detection capabilities may be limited. Thus, this order emphasizes the importance of active engagement with anyone attempting to approach the post, thereby reinforcing safety and security protocols essential for effective guard duty.