Sentinel, Sentry

Sentinel, Sentry (from the Lat. sentire, 'to feel or perceive,' through the Ital. sentinella), a soldier or sailor marine at a point with the duty of watching for the approach of an enemy, or guarding the gun-park, camp, magazine, or other locality. When an army is in the field its front and flanks are protected by 'outposts.' These consist of a chain of pickets (some fifty men each), covered in front by the sentries they throw out, and assisted in rear by other bodies called 'supports.' Each picket would furnish two to four double sentry posts, so that no portion of ground along the front is unwatched. These double sentry posts must be visible to one another and to other sentries (single) who, posted over the piled arms of each picket, report their signals. Sometimes groups of three to six men, one watching, the rest lying down, are used instead of the double sentries. If attacked, sentries fall back on the pickets, and with them retire upon the supports. Each is entrusted with the 'parole' or countersign, and no person, however exalted in position, may approach or pass him without giving that as a signal. As the safety of the army depends upon the vigilance of the sentries, the punishment for sleeping when on sentry-duty on active service is death.