Picket (military)

A picket (archaically, picquet [variant form piquet]) is a soldier, or small unit of soldiers, placed on a defensive line forward of a friendly position to provide timely warning and screening against an enemy advance.

It can also refer to any unit (e.g. a scout vehicle, surveillance aircraft or patrol ship) performing a similar function.

piquet, a pointed stake or peg, from piquer, 'to point or pierce'), is thought to have originated in the French Army around 1690, from the circumstance that an infantry company on outpost duty dispersed its musketeers to watch, with a small group of pikemen called piquet remaining in reserve.

[3] Picket now refers to a unit (either naval or army) maintaining a watch.

Although each soldier is required to maintain watch for the full duration of a shift, halfway through each shift a new soldier is put on watch.