Which order instructs the sentry to maintain vigilance while on duty?

The 2nd Order to the Sentry emphasizes the importance of maintaining alertness and vigilance while on duty. This order specifically instructs sentries to always be on the lookout for anything unusual or suspicious, which is critical for their role in ensuring security. It reinforces the need to remain attentive to their surroundings and ready to respond to any situation that could compromise safety. By following this order, sentries can effectively monitor their assigned area and uphold their responsibilities, which is essential for maintaining order and security in any environment.