In a year when we Americans were first noticed drinking eggnog and firing buckshot, we also contributed to the English language by being on picket. That activity is referred to in a letter to Nathan Hale, who later regretted that he had but one life to give for his country. At the time of the letter, during the siege of Boston, Hale had nothing more to regret than being on military duty out in the countryside, keeping watch over movements of the British army quartered in the city. The letter to Hale, dated December 10, 1775, declares, "Your being on Picquet is a sufficient excuse that you wrote no more."
As that spelling indicates, picquet comes from the French. Earlier in the century the British used it as a designation for sharp-ended tree trunks and posts driven into the ground to form a defensive stockade. Then picquet began to designate soldiers who kept watch, perhaps because they stood like picquets. Our American contribution was the phrase on picquet, used to mean "standing guard." We also helped change the spelling to the modern picket around the time of the Civil War. And in the modern world we keep the original meaning of the word alive by building picket fences.