What is the first order to the sentry?

The correct response identifies the fundamental responsibility of a sentry, serving as the initial order to establish their authority and duties. The order emphasizes the sentry's role in safeguarding both the designated area (the post) and any government property within sight. This sets the foundation for all subsequent actions and responsibilities of the sentry, ensuring they understand the importance of vigilance and control over their environment.

Understanding this order is vital as it underlines the sentry's primary function: to maintain security and order. By taking charge of their post, the sentry not only protects physical assets but also upholds military discipline and vigilance, which are essential components of their duty. This order establishes the expectation of accountability and ownership of the position, which is crucial in a military setting where security is paramount.

In contrast, while the other choices detail important aspects of a sentry's responsibilities—such as the need for alertness, reporting violations, and following commands from superior officers—none capture the immediate and overarching directive that governs the sentry's actions more effectively than the first order. The initial command focuses on the critical aspects of being in charge and responsible for the area, forming the cornerstone of sentry duties.