Picket Duty & Posting Sentries

Picket Duty was essential for the protection of the army. The safety of the entire army (i.e. corps, division, brigade, regiment) was in the hands of these men, and no private was excluded from this duty, except in rare circumstances. More than often, and entire regiment was detailed to picket duty for generally a two day period.
Establishing a picket line around a camp was sometimes quite complicated. Sentinels were posted in three lines:

        1. The Advance Pickets-sometimes a mile or two from camp.
        2. The Second Guard and
        3. The Rear Guard, or Reserves, assigned to the perimeter of the camp. Periodically, "Grand Rounds" was performed. The Officer of the Day, NCO's and a small detachment of men would go from post to post for information and check alertness of the sentries.
The following are Guidelines for Posting Sentinels from 1861 regulations, Hardee's and other sources.
Prior to posting sentinels or relief, two things were done.
        1. Arms Inspection. Load musket and fix bayonet.
        2. Box Inspection. Check Ammunition.
Relief Procedure.
        1. Relief marches at support arms, in two ranks-by the flank, conducted by a corporal. The man on the right of the front rank is "number 1." Should an officer approach, go to shoulder arms.
        2. When a sentinel sees the Relief approaching. he will halt and face it, with arms at shoulder-arms.
        3. At six-paces, the corporal will command: "Relief," and then Halt."
The Relief will shoulder arms. The corporal will then say "Number 1, Number 2," (or whatever number, according to the total number of men at the post) Arms Port""
        4. The two sentinels, both with arms at port, will then approach each other. The old sentinels, under supervision of the corporal, will then whisper instructions and countersign to the new sentinels. This done, the two sentinels will shoulder arms and the old sentinel will pass, in quick time, to his place in the rear of the relief column.
        5. The corporal will then command "Support Arms! Forward! March!" and the Relief proceeds in this manner until all are relieved.
Other Rules and Procedures.
        1. Sentinels will be relieved every two hours (but, we will make it one hour-I hope you don't mind).
        2. The countersign is given to such persons as are entitled to pass during  the night, and to officers, noncoms, and sentinels for the guard.
        3. Sentinels will not take orders or allow themselves to be relieved except by and officer or noncom of the guard party, in which case, the orders are immediately forwarded to the commander of the guard by the officer giving them. An example would be the Recall of the Guard.
        4. Sentinels must keep themselves alert, observing everything that takes  place within sight and hearing of his post. They will carry their arms  habitually at support, or on either shoulder, but will never quit them. In  wet weather, if there is no sentry box, they will secure arms.
        5. No sentinel will quit his post.
        6. Sentinels will present arms to: General Field officers, the Officer of the day, and the Commanding Officer of the Day, and the Commanding Officer of the post. To all other officers the sentinel will shoulder arms.
        7. After retreat or appointed hour, until broad daylight, a sentinel will challenge every person who approaches him, taking at the same time, the  position of Arms Port. "He will not allow any person to come nearer than within reach of his bayonet, until the person has given the countersign.
        8. A sentinel, in challenging, will call out "Who comes there?"
            If answered, "Friend, with the countersign" he will reply "Advance  Friend, with the countersign."
           If answered "Relief", "Patrol" or "Grand Rounds," the sentinel will reply" Halt. Advance Sergeant (or Corporal) with the countersign."
In either instance, the sentinel will ask the countersign and satisfy himself that they are who they claim.
If they have no authority to pass persons with the countersign, if the wrong sign is given, or if the persons have no countersign, the sentinel will cause them to stand and call "Corporal (or Sergeant) of the Guard!"