Origin of Picket Line?

I seem to recall once reading that a picket line is the name for when a horse is left to graze being tethered to a rope - as opposed to being corralled. Is this the correct term, or is there a similar term I may be thinking of?

Probably. A “picket” – meaning a stake in the ground, dates from 1687 and the first reference to a place to tie horses was in 1702.

However, “picket” also has the meaning “a detachment of troops” at the same time.

The OED indicates that “strikers” comes from this definition.

“Picket line” dates from 1768, and derives from the definition “stake” with “line” meaning “rope” (i.e., the rope connecting picket posts). It later was used to mean a line of soldiers (1847) and eventually, a line of strikers (1894).

Huh, crazy. I always figured that it came from the picket signs, which I assumed to be called that because they’re attached to, well, pickets. I had no idea it was the other way around.