Picket guard

Related to Picket guard: picquets
(Mil.) a guard of horse and foot, always in readiness in case of alarm.

See also: Picket

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in classic literature ?
I went and found Mary, the picket guard half asleep, and longing for her share of the feast.
Likewise, a separate "The Picket Guard," published in March 1862 in the Richmond Dispatch, imagined a guard "at his lonely post" who felt "the foe's first deadly brunt" and died.(85) Such poems were part of a popular literature that vicariously embraced the violence of war, as Charles Royster has pointed out.(86) But this embrace did not necessarily mean a shallow celebration of violence; rather, the many sentimental soldier poems published in wartime sought to comprehend and make sense of the violence of war individual by individual, and life by life--a task that grew ever more formidable over the course of the conflict.
The authorship of "The Picket Guard" was contested, with both Northern and Southern authors claiming to have written it.