When you are a sentry, you are "in charge." This means that no one—no matter what their rank or position—may overrule your authority in carrying out your orders. The only way that you may be exempted from carrying out your orders is if your orders are changed by your superior. For example, if your orders are to allow no one to enter a fenced-in compound, you must prevent everyone from entering, even if an admiral tells you it is all right for him or her to enter. The petty officer of the watch (or whoever is your immediate superior) may modify your orders to allow the admiral to enter, but without that authorization you must keep the admiral out. Situations such as this will not often, if ever, occur, but it is important that you understand the principles involved. It is also your responsibility to know the limits of your post. This information will be conveyed to you among your special orders. You must also treat all government property that you can see as though it were your own, even if it is not technically part of your assigned post.〔, The Bluejacket's Manual, ''Thomas J. Cutler''〕

"Keep your eyes peeled", as the expression goes. Be vigilant by looking around at all times. Do not be tempted to hide from the rain or cold in poor weather. If you see or hear anything unusual, investigate it.〔

If, for example, someone is climbing a fence near your post, you must report it, even if the offender stops climbing and runs away after your challenge. In this case, even though it appears that the threat to security is over, there is no way for you to know whether this violator is the only one involved. And even though the climber may have just been seeking a shortcut back to her or his ship, you cannot be certain that there is not something more sinister involved. Let your superiors make the judgment calls; your job is to report what happens on or near your post.〔

"In these days of modern communications, sentries will probably have telephones or radios at their disposal with which to make their reports. But if they do not, or if there is a power failure or some other reason that the modern equipment fails, the age-old practice of relaying the word is very important. The term "guardhouse" in this general order refers to the command post or point of control for the watches. It might be the quarterdeck on board ship or a tent in the field.〔

It should be fairly obvious that you should not leave your post until someone has come to take your place or until the petty officer of the guard has told you that the watch is no longer necessary. If the person relieving you is late, report it to the petty officer of the watch but do ''not'' quit your post. If you become ill and can no longer stand your watch, notify the petty officer of the watch and he or she will provide you a proper relief.〔

It is essential that you receive and obey all of the special orders that apply to your watch. It is also essential that you pass these orders on to your relief.〔

For the Marine Corps it reads 'Commanding Officer, Officer of the Day, Officers, and Non-Commissioned Officers of the guard only.'

"Having conversations about matters not pertaining to your duty is distracting and must be avoided. If someone tries to engage you in casual conversation while you are standing your watch, it is your responsibility to inform them courteously that you are on duty and cannot talk with them.〔

"While this is rather straightforward and obvious, keep in mind that a fire or disorder of some kind might be a deliberate distraction to keep you from observing some other disorderly or subversive activity. If you are certain that a fire is not meant to be a distraction, you should fight the fire if you have the means to do so. Remember, however, that your first responsibility is to ''report'' whatever is amiss.〔

The rule here is "When in doubt, ask." If you are not sure what you are supposed to do in a particular situation, it is better to ask for clarification than to make an assumption or to guess.〔

Even though you are in charge of your post and everyone, including officers, must obey your instructions insofar as they pertain to your duties, you must still extend the appropriate military courtesies. Both terms, "colors" and "standards", refer to the national ensign. The national ensign may be referred to as "the colors" when it is fixed to a staff, mast, or pike (e.g., when flown from a flagstaff or carried in a parade). When it is fixed to a vehicle it is often called "the national standard." A flag is considered "cased" when it is furled and placed in a protective covering. If your duties allow, you should take part in morning or evening colors ceremonies, but do not sacrifice your vigilance by doing so. For example, if your assignment requires that you watch a certain area and the national ensign is being hoisted in a different direction, you should stand at attention and salute but do not face the colors; keep looking in the direction you are supposed to be watching.〔

Challenging persons while you are on sentry duty is accomplished by a mix of custom and common sense. When a person or party approaches your post, you should challenge them at a distance that is sufficient for you to react if they turn out to have hostile intentions. You should say in a firm voice, loud enough to be easily heard, "Halt! Who goes there?" (or "Who is there?"). Once the person answers, you should then say "Advance to be recognized." If you are challenging a group of people, you should say, "Advance ''one'' to be recognized." If you have identified the person or persons approaching, permit them to pass. If you are not satisfied with that person's identification, you must detain the person and call the petty officer of the watch. When two or more individuals approach from different directions at the same time, challenge each in turn and require each to halt until told to proceed.〔